National Instruments Network Card GPIB PC User Manual

GPIB-PC User Manual

for the

IBM Personal Computer and

Compatibles

April 1988 Edition

Part Number 320014-01

Limited Warranty

The GPIB-PC is warranted against defects in materials and workmanship

for a period of two years from the date of shipment, as evidenced by

receipts or other documentation. National Instruments will, at its option,

repair or replace equipment that proves to be defective during the warranty

period. This warranty includes parts and labor.

The media on which you receive National Instruments software are

warranted not to fail to execute programming instructions, due to defects in

materials and workmanship, for a period of 90 days from date of shipment,

as evidenced by receipts or other documentation. National Instruments will,

at its option, repair or replace software media that do not execute

programming instructions if National Instruments receives notice of such

defects during the warranty period. National Instruments does not warrant

that the operation of the software shall be uninterrupted or error free.

A Return Material Authorization (RMA) number must be obtained from the

factory and clearly marked on the outside of the package before any

equipment will be accepted for warranty work. National Instruments will

pay the shipping costs of returning to the owner parts which are covered by

warranty.

National Instruments believes that the information in this manual is

accurate. The document has been carefully reviewed for technical

accuracy. In the event that technical or typographical errors exist, National

Instruments reserves the right to make changes to subsequent editions of

this document without prior notice to holders of this edition. The reader

should consult National Instruments if errors are suspected. In no event

shall National Instruments be liable for any damages arising out of or

related to this document or the information contained in it.

EXCEPT AS SPECIFIED HEREIN, NATIONAL INSTRUMENTS MAKES NO

WARRANTIES, EXPRESS OR IMPLIED, AND SPECIFICALLY DISCLAIMS

ANY WARRANTY OF MERCHANTABILITY OR FITNESS FOR A

PARTICULAR PURPOSE. CUSTOMER'S RIGHT TO RECOVER DAMAGES

CAUSED BY FAULT OR NEGLIGENCE ON THE PART OF NATIONAL

INSTRUMENTS SHALL BE LIMITED TO THE AMOUNT THERETOFORE

PAID BY THE CUSTOMER. NATIONAL INSTRUMENTS WILL NOT BE

LIABLE FOR DAMAGES RESULTING FROM LOSS OF DATA, PROFITS,

USE OF PRODUCTS, OR INCIDENTAL OR CONSEQUENTIAL DAMAGES,

EVEN IF ADVISED OF THE POSSIBILITY THEREOF. This limitation of the

liability of National Instruments will apply regardless of the form of action,

whether in contract or tort, including negligence. Any action against

National Instruments must be brought within one year after the cause of

action accrues. National Instruments shall not be liable for any delay in

performance due to causes beyond its reasonable control. The warranty

provided herein does not cover damages, defects, malfunctions, or service

failures caused by owner's failure to follow the National Instruments

installation, operation, or maintenance instructions; owner's modification of

the product; owner's abuse, misuse, or negligent acts; and power failure or

surges, fire, flood, accident, actions of third parties, or other events outside

reasonable control.

Under the copyright laws, this publication may not be reproduced or

transmitted in any form, electronic or mechanical, including photocopying,

recording, storing in an information retrieval system, or translating, in

whole or in part, without the prior written consent of National Instruments

Corporation.

Trademarks

Product and company names listed are trademarks or trade names of their

respective companies.

WARNING REGARDING MEDICAL AND

CLINICAL USE OF NATIONAL

INSTRUMENTS PRODUCTS

National Instruments products are not designed with components and

testing intended to ensure a level of reliability suitable for use in treatment

and diagnosis of humans. Applications of National Instruments products

involving medical or clinical treatment can create a potential for accidental

injury caused by product failure, or by errors on the part of the user or

application designer. Any use or application of National Instruments

products for or involving medical or clinical treatment must be performed

by properly trained and qualified medical personnel, and all traditional

medical safeguards, equipment, and procedures that are appropriate in the

particular situation to prevent serious injury or death should always

continue to be used when National Instruments products are being used.

National Instruments products are NOT intended to be a substitute for any

form of established process, procedure, or equipment used to monitor or

safeguard human health and safety in medical or clinical treatment.

Preface

Introduction to the GPIB

The GPIB is a link, or bus, or interface system, through which

interconnected electronic devices communicate.

History of the GPIB

The original GPIB was designed by Hewlett-Packard (where it is called

the HP-IB) to connect and control programmable instruments

manufactured by Hewlett-Packard. Because of its high data transfer

rates of from 250 kilobytes to 1 megabyte per second, the GPIB quickly

gained popularity in other applications such as intercomputer

communication and peripheral control. It was later accepted as the

industry standard IEEE-488. The versatility of the system prompted the

name General Purpose Interface Bus.

National Instruments expanded the use of the GPIB among users of

computers manufactured by companies other than Hewlett-Packard.

National Instruments specialized both in high performance, high-speed

hardware interfaces, and in comprehensive, full-function software that

helps users bridge the gap between their knowledge of instruments and

computer peripherals and of the GPIB itself.

The GPIB-PC Family

The GPIB-PC family consists of GPIB interface hardware products,

software, documentation, and other items for several types of personal

computers.

What Your Package Should Contain

Unless you have a special application, your GPIB-PC package consists

of the following:

• A GPIB-PC interface board for your personal computer. Each

board has a model name such as GPIB-PCIIA. This manual uses

GPIB-PC to refer generally to all models of the GPIB-PC

interface board.

©National Instruments Corp.

GPIB-PC User Manual

Preface

• A Getting Started with your GPIB-PC pamphlet. The pamphlet

contains the directions with a minimum of explanations for

installing your hardware and software in your GPIB system.

• A GPIB-PC distribution diskette. The distribution diskette is part

of the GPIB-PC package. It contains the DOS handler, BASICA

and QuickBASIC language interfaces, and other programs.

• A GPIB-PC User Manual. The manual contains descriptions of

the GPIB-PC handler functions, BASICA, and QuickBASIC

language interfaces to the handler.

• A Programmer Reference Guide for BASIC.

• A supplement to Section Two of the manual describing your

particular interface board and how to install it in your personal

computer.

For a language other than BASICA and QuickBASIC, you also need:

• An additional GPIB-PC distribution diskette containing the

software for that language.

• A supplement to Section Four describing the GPIB functions in

the syntax and semantics of that language.

• A Programmer Reference Guide for that language.

Who Are Our Users?

Most of our users have experience in technological fields and with

computers.

How to Get Started

If you already have experience with the GPIB, you may wish to turn

directly to the Getting Started with your GPIB-PC pamphlet that was

shipped with your hardware. It contains directions, with a minimum of

explanations, for installing your hardware and software in your GPIB

system.

If you are less experienced or want more information than the pamphlet

provides, read this GPIB-PC User Manual. It explains in detail all of the

information you will need for the proper operation of the GPIB-PC.

GPIB-PC User Manual

©National Instruments Corp.

Preface

About the Manual

This manual is written specifically for a GPIB-PC which is to be

installed in an IBM Personal Computer or compatible PC which is

operating under PC-DOS or MS-DOS and programmed using BASICA

and QuickBASIC. With appropriate supplements to the manual, other

GPIB-PC interfaces can be installed in other computers, using other

programming languages.

Organization of the Manual

Section One - Operation of the GPIB describes the operation of the

GPIB.

Section Two - Installation and Configuration describes the installation of

the software and the configuration program IBCONF. A supplement

contains instructions for installing your particular board into your

computer.

Section Three - GPIB-PC Functions — Introduction introduces you to the

functions used by your GPIB-PC. The features are divided into groups

as a means of helping you understand the uses of the functions.

Section Four - GPIB-PC Functions — Overview introduces you to

programming information common to all languages.

Section Four A - Function Reference — Language Interface(s) pertains to

BASICA and QuickBASIC. The descriptions are listed alphabetically

for easy reference.

Section Five - IBIC introduces you to IBIC, the interactive control

program that allows you to control and communicate with the GPIB

through functions you enter at your keyboard. IBIC is designed to help

you learn how to use the GPIB-PC functions to program your devices.

Section Six - Applications Monitor introduces you to the applications

monitor, a resident program that is useful in debugging sequences of

GPIB calls from within your application.

Appendix A - Multiline Interface Messages is a listing of Multiline

Interface Command Messages.

Appendix B - Common Errors and Their Solutions singles out the most

common errors users have encountered and some probable solutions.

©National Instruments Corp.

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GPIB-PC User Manual

Preface

Appendix C - Differences Between Software Revisions points out

differences between revisions of the GPIB-PC handler.

Appendix D - Using your Printer with the GPIB-PC gives some quick

steps to connect your GPIB-PC with your printer.

Appendix E - Application Notes is an application note about computer-

to-computer transfers.

Appendix F - Customer Communication contains forms you can use to

request help from National Instruments or to comment on our products

and manuals.

The Glossary contains an alphabetical list and description of terms used

in this manual, including abbreviations, acronyms, metric prefixes,

mnemonics, and symbols.

The Index contains an alphabetical list of key terms and topics in this

manual, including the page where you can find each one.

Now, with your personal computer, your GPIB-PC, your manuals and

supplements, and these instructions, you are ready to get started with

your GPIB. We hope your experience will be a rewarding one.

Customer Support

National Instruments wants to receive your comments on our products

and manuals. We are interested in the applications you develop with

our products, and we want to help if you have problems with them. For

information on how to contact us, refer to Appendix F, Customer

Communication, at the end of this manual.

GPIB-PC User Manual

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©National Instruments Corp.

Contents

Section One - Operation of the GPIB................................................1-1

Types of Messages......................................................................................1-1

Talkers, Listeners, and Controllers.....................................................1-1

The Controller-In-Charge and System Controller.........................1-2

GPIB Signals and Lines...........................................................................1-3

Data Lines.....................................................................................1-3

Handshake Lines........................................................................1-3

NRFD (not ready for data)..................................1-3

NDAC (not data accepted).................................1-4

DAV (data valid).....................................................1-4

Interface Management Lines...............................................1-4

ATN (attention)........................................................1-4

IFC (interface clear)..............................................1-4

REN (remote enable)............................................1-4

SRQ (service request)...........................................1-5

EOI (end or identify)..............................................1-5

Physical and Electrical Characteristics............................................1-5

Configuration Requirements...................................................................1-9

Related Documents....................................................................................1-9

Section Two - Installation and Configuration............................2-1

Installing the Hardware.............................................................................2-1

The GPIB-PC Software Package.........................................................2-1

Additional Programs and Files............................................2-2

Installing the Software..............................................................................2-3

Step 1 - Preparation..................................................................2-3

Booting from a Floppy Disk...............................2-3

Booting from a Hard Disk....................................2-3

Step 2 - Run IBSTART...........................................................2-4

Step 3 - Run IBCONF (optional).......................................2-5

Step 4 - Reboot...........................................................................2-5

Step 5 - Test Software Installation....................................2-5

More About IBCONF.................................................................................2-6

Characteristics of the Instruments.....................................2-7

Characteristics of each GPIB-PC......................................2-7

Default Configurations..............................................................................2-8

Primary Default Characteristics.........................................2-8

©National Instruments Corp.

GPIB-PC User Manual

Contents

Running IBCONF........................................................................................2-9

Upper and Lower Levels of IBCONF............................2-10

Upper Level - Device Map

for Board GPIBx.................................................... 2-10

Device Map Concepts and Terms................ 2-11

Lower Level - Device/Board

Characteristics....................................................... 2-11

Device and Board Characteristics..................................2-12

Primary GPIB Address....................................... 2-12

Secondary GPIB Address..................................2-12

Timeout Settings................................................... 2-12

EOS Byte.................................................................. 2-14

EOS Modes..............................................................2-14

Set EOI with last byte of Write..................... 2-14

GPIB-PC Model.................................................... 2-14

Board is System Controller

(Boards Only)......................................................... 2-14

Local Lockout on all Devices

(Boards Only)......................................................... 2-15

Disable Auto Serial Polling

(Boards Only)......................................................... 2-15

High-Speed Timing

(Boards Only)......................................................... 2-15

Interrupt Jumper Setting

(Boards Only)......................................................... 2-15

Base I/O Address (Boards Only)...................2-15

DMA Channel (Boards Only).........................2-16

Internal Clock Frequency

(Boards Only)......................................................... 2-16

Exiting IBCONF...................................................................... 2-16

Using Your GPIB-PC.............................................................................. 2-18

Section Three - GPIB-PC

Functions — Introduction............................................................................3-1

Introduction to the GPIB-PC Functions............................................3-1

High-Level Functions..............................................................3-1

Low-Level Functions...............................................................3-1

Calling Syntax............................................................................3-1

Group I..............................................................................................................3-2

IBRD (bd,buf,cnt).....................................................................3-2

IBWRT (bd,buf,cnt).................................................................3-2

IBFIND (bdname,bd)...............................................................3-3

GPIB-PC User Manual

©National Instruments Corp.

Contents

Group II.............................................................................................................3-3

IBRSP (bd,spr) ...........................................................................3-3

IBCLR (bd)..................................................................................3-4

Clearing the Device Versus

Clearing the GPIB...................................................3-4

Clearing the Device.............................3-4

Clearing the GPIB.................................3-4

IBTRG (bd)..................................................................................3-4

IBLOC (bd)..................................................................................3-4

Placing a Device in Remote Mode................3-4

Placing a Device in Local Mode.....................3-5

Group III...........................................................................................................3-5

IBRDA (bd,buf,cnt) and.........................................................3-6

IBRDF (bd,buf,cnt) and.........................................................3-6

IBWAIT (bd,mask)...................................................................3-6

IBSTOP (bd)................................................................................3-6

IBTMO (bd,v).............................................................................3-7

IBONL (bd,v)..............................................................................3-7

IBPCT (bd)...................................................................................3-7

Group IV...........................................................................................................3-8

Purpose of Board Functions..................................................3-9

Multiboard Capability.............................................................3-9

IBFIND (bdname,bd)............................................................ 3-10

IBCMD (bd,buf,cnt) and..................................................... 3-10

IBRD (bd,buf,cnt) and......................................................... 3-10

IBWRT (bd,buf,cnt) and..................................................... 3-12

IBSTOP (bd)............................................................................. 3-12

IBWAIT (bd,mask)................................................................3-12

IBTMO (bd,v).......................................................................... 3-12

IBONL (bd,v)........................................................................... 3-12

IBSIC (bd)................................................................................. 3-12

IBSRE (bd,v)............................................................................3-13

IBGTS (bd,v)............................................................................ 3-13

IBCAC (bd,v)...........................................................................3-13

IBRPP (bd,buf)........................................................................ 3-13

IBPPC (bd,v)............................................................................ 3-13

More About Device and Board Functions....................................3-14

Group V......................................................................................................... 3-15

IBRSV (bd,v)........................................................................... 3-15

IBLOC (bd)............................................................................... 3-15

IBPPC (bd,v)............................................................................ 3-16

IBIST (bd,v)..............................................................................3-16

IBWAIT (bd,mask)................................................................3-16

©National Instruments Corp.

GPIB-PC User Manual

Contents

Group VI........................................................................................................3-17

IBEOT (bd,v)............................................................................ 3-17

IBEOS (bd,v)............................................................................ 3-18

IBBNA (bd,"GPIBn")........................................................... 3-18

IBDMA (bd,v)..........................................................................3-18

IBPAD (bd,v)........................................................................... 3-18

IBSAD (bd,v)........................................................................... 3-18

IBRSC (bd,v)........................................................................... 3-18

IBTMO (bd,v).......................................................................... 3-18

Section Four - GPIB-PC

Functions — Overview................................................................................. 4-1

General Programming Information................................................... 4-1

Status Word.................................................................................................4-2

Error Codes.................................................................................................. 4-6

Count Variable.........................................................................................4-11

Read and Write Termination............................................................ 4-11

Device Function Calls......................................................................... 4-12

Automatic Serial Polling.................................................................... 4-13

Section Four A - BASICA/QuickBASIC

GPIB-PC Function Calls......................................................................... 4A-1

BASICA Files.......................................................................................... 4A-2

QuickBASIC Files................................................................................. 4A-2

Programming Preparations for BASICA.................... 4A-3

Programming Preparations for QuickBASIC........... 4A-4

BASICA/QuickBASIC GPIB-PC I/O Functions...................... 4A-5

BASICA/QuickBASIC "ON SRQ" Capability..........................4A-6

New GPIB-PC Functions..................................................................4A-12

GPIB-PC Function Descriptions....................................................4A-15

IBBNA.........................................................................................................................4A-16

IBCAC.........................................................................................................................4A-17

IBCLR..........................................................................................................................4A-19

IBCMD........................................................................................................................4A-20

IBCMDA.....................................................................................................................4A-23

IBDMA........................................................................................................................4A-25

IBEOS..........................................................................................................................4A-26

IBEOT..........................................................................................................................4A-30

IBFIND........................................................................................................................4A-32

IBGTS..........................................................................................................................4A-34

IBIST............................................................................................................................4A-36

IBLOC..........................................................................................................................4A-38

IBONL..........................................................................................................................4A-40

IBPAD..........................................................................................................................4A-42

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©National Instruments Corp.

Contents

IBPCT..........................................................................................................................4A-44

IBPPC..........................................................................................................................4A-45

IBRD.............................................................................................................................4A-47

IBRDA ........................................................................................................................4A-50

IBRDF..........................................................................................................................4A-54

IBRDI...........................................................................................................................4A-57

IBRDIA........................................................................................................................4A-60

IBRPP..........................................................................................................................4A-64

IBRSC..........................................................................................................................4A-66

IBRSP..........................................................................................................................4A-68

IBRSV..........................................................................................................................4A-70

IBSAD..........................................................................................................................4A-71

IBSIC............................................................................................................................4A-73

IBSRE..........................................................................................................................4A-74

IBSTOP.......................................................................................................................4A-76

IBTMO.........................................................................................................................4A-78

IBTRAP.......................................................................................................................4A-81

IBTRG..........................................................................................................................4A-83

IBWAIT.......................................................................................................................4A-84

IBWRT........................................................................................................................4A-87

IBWRTA.....................................................................................................................4A-90

IBWRTF .....................................................................................................................4A-93

IBWRTI.......................................................................................................................4A-95

IBWRTIA ..................................................................................................................4A-99

BASICA/QuickBASIC GPIB

Programming Examples...................................................................4A-103

BASICA Example Program - Device......................4A-105

BASICA Example Program - Board........................4A-108

QuickBASIC Example Program - Device.............4A-111

QuickBASIC Example Program - Board...............4A-114

Section Five - IBIC..............................................................................................5-1

Running IBIC.................................................................................................5-2

Using HELP..................................................................................5-3

Using IBFIND..............................................................................5-3

Using IBWRT..............................................................................5-4

Using IBRD..................................................................................5-4

How to Exit IBIC.......................................................................5-5

Important Programming Note...............................................5-5

Using SET.....................................................................................5-6

IBIC Functions and Syntax.....................................................................5-7

Other IBIC Functions and Syntax........................................................5-8

Status Word.................................................................................................5-10

Error Code.................................................................................................... 5-11

©National Instruments Corp.

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Contents

Byte Count................................................................................................... 5-12

Auxiliary Functions................................................................................. 5-12

SET (Select Device or Board).........................................5-13

HELP (Display Help Information)..................................5-13

! (Repeat Previous Function)........................................... 5-14

- (Turn OFF Display)............................................................5-14

+ (Turn ON Display)............................................................. 5-15

n* (Repeat Function n Times).........................................5-16

$ (Execute Indirect File).................................................... 5-17

PRINT (Display the ASCII String)................................ 5-18

E or Q (exit or quit)............................................................... 5-18

IBIC Sample Programs.......................................................................... 5-19

Device Function Calls......................................................... 5-19

Board Function Calls............................................................5-22

Section Six - Applications Monitor.......................................................6-1

Installing the Applications Monitor....................................................6-2

IBTRAP..........................................................................................6-2

Applications Monitor Options................................................................6-5

Main Commands..........................................................................................6-6

Session Summary Screen........................................................................6-7

Configuring the Trap Mask.....................................................................6-7

Configuring the Monitor Mode..............................................................6-7

Hiding and Showing the Monitor.......................................6-8

Appendix A - Multiline Interface Messages.................................A-1

Multiline Interface Messages................................................................A-2

Interface Message Reference List.......................................................A-4

Appendix B - Common Errors

and Their Solutions.............................................................................................B-1

EDVR(0)..........................................................................................................B-1

ECIC(1)............................................................................................................B-1

ENOL(2)..........................................................................................................B-2

EADR(3)..........................................................................................................B-3

EARG(4)..........................................................................................................B-3

ESAC(5)..........................................................................................................B-4

EABO(6)..........................................................................................................B-4

ENEB(7)..........................................................................................................B-5

EOIP(10)..........................................................................................................B-5

ECAP(11)........................................................................................................B-5

EFSO(12)........................................................................................................B-5

EBUS(14)........................................................................................................B-6

ESTB(15)........................................................................................................B-6

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Contents

ESRQ(16)........................................................................................................B-6

Other Error Conditions...............................................................................B-7

Appendix C - Differences Between

Software Revisions...............................................................................................C-1

Revision B and Revision C....................................................................C-1

Interrupts........................................................................................C-1

Startup Program..........................................................................C-1

Configuration Program............................................................C-1

Interface Bus Interactive Control Program (IBIC)....C-1

New Functions............................................................................C-2

Modified Functions...................................................................C-2

Language Interfaces.................................................................C-2

General...........................................................................................C-2

Revision C and Revision D....................................................................C-2

Device Functions.......................................................................C-2

Non-Interrupt Mode...................................................................C-2

Asynchronous I/O.......................................................................C-3

DMA on the GPIB-PCIII........................................................C-3

Local Lockout.............................................................................C-3

SRQI Status Bit..........................................................................C-3

ATN and/or TIMO.....................................................................C-3

DCAS and DTAS Status Bits..............................................C-3

Printer Support............................................................................C-3

Appendix D - Using your Printer

with the GPIB-PC...............................................................................................D-1

Installation......................................................................................................D-1

Appendix E - Application Notes..............................................................E-1

Application Note 1 - Computer to Computer

Data Transfer.................................................................................................E-1

Step 1. Configure the Computers......................................E-1

Step 2. Establish Communication....................................E-1

Step 3. Transfer Data..............................................................E-2

Appendix F - Customer Communication.......................................F-1

Glossary.........................................................................................................................G-1

Index.................................................................................................................................I-1

©National Instruments Corp.

GPIB-PC User Manual

Illustrations

List of Figures

Figure 1.1 - GPIB Connector and the Signal Assignment......................... 1-6

Figure 1.2 - Linear Configuration.......................................................................... 1-7

Figure 1.3 - Star Configuration............................................................................... 1-8

Figure 3.1 - Multiboard GPIB System............................................................... 3-11

Figure 6.1 - Applications Monitor Popup Screen........................................... 6-1

List of Tables

Table 2.1 - Timeout Settings................................................................................. 2-13

Table 2.2 - Functions that Alter Default Characteristics......................... 2-17

Table 4.1 - Status Word Layout............................................................................. 4-2

Table 4.2 - GPIB Error Codes.................................................................................. 4-6

Table 4A.1 - BASICA GPIB-PC Functions..................................................4A-7

Table 4A.2 - QuickBASIC GPIB-PC Calls...................................................4A-8

Table 4A.3 - QuickBASIC GPIB-PC Calls.................................................4A-10

Table 4A.4 - QuickBASIC Version 4.0 GPIB-PC Functions..............4A-14

Table 5.1 - Syntax of GPIB Functions in IBIC............................................... 5-8

Table 5.2 - Status Word Layout........................................................................... 5-11

Table 5.3 - Auxiliary Functions that IBIC Supports................................... 5-12

©National Instruments Corp.

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GPIB-PC User Manual

Section One - Operation of the GPIB

Communication between interconnected devices is achieved by passing

messages through the interface system.

Types of Messages

The GPIB carries two types of messages — device-dependent messages

and interface messages.

• Device-dependent messages, often called data or data messages,

contain device-specific information such as programming

instructions, measurement results, machine status, and data files.

• Interface messages manage the bus itself. They are usually

called commands or command messages. Interface messages

perform such functions as initializing the bus, addressing and

unaddressing devices, and setting device modes for remote or

local programming.

The term command as used here should not be confused with some

device instructions which can also be called commands. Such device-

specific instructions are actually data messages.

Talkers, Listeners, and Controllers

A Talker sends data messages to one or more Listeners. The Controller

manages the flow of information on the GPIB by sending commands to

all devices.

Devices can be Listeners, Talkers, and/or Controllers. A digital

voltmeter, for example, is a Talker and may be a Listener as well.

The GPIB is a bus like an ordinary computer bus except that the

computer has its circuit cards interconnected via a backplane bus

whereas the GPIB has standalone devices interconnected via a cable

bus.

The role of the GPIB Controller can also be compared to the role of the

computer's CPU, but a better analogy is to the switching center of a city

telephone system.

©National Instruments Corp.

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GPIB-PC User Manual

Operation of the GPIB

Section One

The switching center (Controller) monitors the communications network

(GPIB). When the Controller notices that a party (device) wants to

make a call (send a data message), it connects the caller (Talker) to

the receiver (Listener).

The Controller usually addresses a Talker and a Listener before the

Talker can send its message to the Listener. After the message is

transmitted, the Controller usually unaddresses both devices.

Some bus configurations do not require a Controller. For example, one

device may always be a Talker (called a Talk-only device) and there

may be one or more Listen-only devices.

A Controller is necessary when the active or addressed Talker or

Listener must be changed. The Controller function is usually handled by

a computer.

With the GPIB-PC interface board and its software, your personal

computer plays all three roles:

•

Controller - to manage the GPIB,

Talker - to send data, and

Listener - to receive data.

The Controller-In-Charge and System Controller

Although there can be multiple Controllers on the GPIB, only one

Controller at a time is active, or Controller-In-Charge (CIC). Active

control can be passed from the current CIC to an idle Controller. Only

one device on the bus, the System Controller, can make itself the CIC.

The GPIB-PC is usually the System Controller.

GPIB-PC User Manual

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©National Instruments Corp.

Section One

Operation of the GPIB

GPIB Signals and Lines

The interface system consists of 16 signal lines and 8 ground return or

shield drain lines.

The 16 signal lines are divided into the following three groups:

•

8 data lines,

3 handshake lines, and

5 interface management lines.

Data Lines

The eight data lines, DIO1 through DIO8, carry both data and command

messages. All commands and most data use the 7-bit ASCII or ISO

code set, in which case the 8th bit, DIO8, is unused or used for parity.

Handshake Lines

Three lines asynchronously control the transfer of message bytes

between devices:

•

NRFD,

NDAC, and

DAV.

The process is called a three-wire interlocked handshake and it

guarantees that message bytes on the data lines are sent and received

without transmission error.

NRFD (not ready for data)

NRFD indicates when a device is ready or not ready to receive a

message byte. The line is driven by all devices when receiving

commands and by Listeners when receiving data messages.

©National Instruments Corp.

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GPIB-PC User Manual

Operation of the GPIB

Section One

NDAC (not data accepted)

NDAC indicates when a device has or has not accepted a message byte.

The line is driven by all devices when receiving commands and by

Listeners when receiving data messages.

DAV (data valid)

DAV tells when the signals on the data lines are stable (valid) and can

be accepted safely by devices. The Controller drives DAV lines when

sending commands and the Talker drives DAV lines when sending data

messages.

Interface Management Lines

Five lines are used to manage the flow of information across the

interface:

•

ATN,

IFC,

REN,

SRQ, and

EOI.

ATN (attention)

The Controller drives ATN true when it uses the data lines to send

commands and false when it allows a Talker to send data messages.

IFC (interface clear)

The System Controller drives the IFC line to initialize the bus and

become CIC.

REN (remote enable)

The System Controller drives the REN line, which is used to place

devices in remote or local program mode.

GPIB-PC User Manual

1-4

©National Instruments Corp.

Section One

Operation of the GPIB

SRQ (service request)

Any device can drive the SRQ line to asynchronously request service

from the Controller.

EOI (end or identify)

The EOI line has two purposes. The Talker uses the EOI line to mark

the end of a message string. The Controller uses the EOI line to tell

devices to identify their response in a parallel poll.

Physical and Electrical Characteristics

Devices are usually connected with a cable assembly consisting of a

shielded 24-conductor cable with both a plug and receptacle connector

at each end. This design allows devices to be linked in either a linear

or a star configuration, or a combination of the two. See Figures 1.1,

1.2, and 1.3.

The standard connector is the Amphenol or Cinch Series 57

MICRORIBBON or AMP CHAMP type. An adapter cable using non-

standard cable and/or connector is used for special interconnect

applications.

The GPIB uses negative logic with standard TTL logic level. When

DAV is true, for example, it is a TTL low-level ( ≤ 0.8V), and when

DAV is false, it is a TTL high-level ( ≥ 2.0V).

©National Instruments Corp.

1-5

GPIB-PC User Manual

Operation of the GPIB

Section One

DIO1

DIO2

DIO3

DIO4

EOI

DAV

NRFD

NDAC

IFC

SRQ

ATN

DIO5

DIO6

DIO7

DIO8

REN

GND (TW PAIR W/DAV)

GND (TW PAIR W/NRFD)

GND (TW PAIR W/NDAC)

GND (TW PAIR W/IFC)

GND (TW PAIR W/SRQ)

10 22

11 23

12 24

GND (TW PAIR W/ATN)

SIGNAL GROUND

SHIELD

Figure 1.1 - GPIB Connector and the Signal Assignment

GPIB-PC User Manual

1-6

©National Instruments Corp.

Section One

Operation of the GPIB

Figure 1.2 - Linear Configuration

©National Instruments Corp.

1-7

GPIB-PC User Manual

Operation of the GPIB

Section One

Figure 1.3 - Star Configuration

GPIB-PC User Manual

1-8

©National Instruments Corp.

Section One

Operation of the GPIB

Configuration Requirements

To achieve the high data transfer rate that the GPIB was designed for,

the physical distance between devices and the number of devices on the

bus are limited.

The following restrictions are typical.

• A maximum separation of four meters between any two devices

and an average separation of two meters over the entire bus.

• A maximum total cable length of 20 meters.

• No more than 15 devices connected to each bus, with at least

two-thirds powered on.

Bus extenders are available from National Instruments and other

manufacturers for use when these limits must be exceeded.

Related Documents

For more information on topics covered in this section consult the

following related documents.

• IEEE Std. 488-1978, IEEE Standard Digital Interface for

Programmable Instrumentation.

• GPIB-PC Technical Reference Manual.

©National Instruments Corp.

1-9

GPIB-PC User Manual

Section Two - Installation and

Configuration

The procedures for installing your GPIB-PC depend on your model of

board and your make of computer. A supplement to Section Two

contains information about your interface board. Section Two A, for

example, contains information about the model GPIB-PCIIA for the IBM

PC and compatible computers.

Installing the Hardware

To install your hardware, follow the instructions in the Section Two

supplement for your interface board.

If you change the default settings of any switches, make a note of the

new values so that you can refer to them when you configure your

software.

Install the hardware before continuing.

The GPIB-PC Software Package

Before you install your software, you might wish to review the files on

your GPIB-PC distribution diskette to gain an understanding of what

they are.

The following files are the main files of the GPIB-PC software:

• GPIB.COM - is a device handler file that is loaded at system

start-up by the DOS operating system. Handler is a term used

by National Instruments to refer to a loadable device driver.

• BIB.M - is a language interface file that provides an

application program access to the GPIB-PC handler. BIB.Mis

intended for use with programs written in BASICA.

• QBIB*.OBJ- is a language interface file that provides an

application program access to the GPIB-PC handler.

QBIB*.OBJis intended for use with programs written in

QuickBASIC.

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Section Two

• DECL.BAS - is a declaration file that contains code to be

placed at the beginning of the BASICA and QuickBASIC

application programs.

• QBDECL.BAS - is a declaration file that contains code to be

placed at the beginning of the QuickBASIC application

programs.

Additional Programs and Files

The following additional programs and files include installation, test,

and example programs:

• APPMON.COM- is the applications monitor program. It is a

resident program that is useful in debugging sequences of GPIB

calls from within your application. The applications monitor

provides the capability to trap on return from GPIB driver calls,

allowing you to inspect function arguments, buffers, return

values, GPIB global variables, and other pertinent data.

• IBTRAP.EXE- is a program that configures the applications

monitor.

• IBSTART.BAT- is a batch file used for installation and start-

up. It is a multipurpose program that performs the software

installation. It copies files, modifies CONFIG.SYS(the DOS

system configuration file) using MKCFG.EXE, and tests the

hardware using IBDIAG.EXE.

• IBDIAG.EXE- is a program that tests the hardware installation

before the GPIB software is configured and installed. After the

handler is installed, IBTEST.BATconfirms that both the

software and hardware are installed and functioning properly.

The test is executed in two parts using IBTSTA.EXEand

IBTSTB.EXE.

• IBCONF.EXE- is a software configuration program that allows

you to change the software parameters and other data used by

the handler.

• IBIC.EXE- is an interactive control program that allows you

to execute the handler functions interactively from your

keyboard. It helps you to learn the functions, to program your

instrument or other GPIB device, and to develop your

application program.

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Section Two

Installation and Configuration

• DBSAMP.BAS, BBSAMP.BAS, DQBSAMP, BIBSAMP, and

DIBSAMP- are example programs for BASICA, QuickBASIC,

and IBIC. The BASICA and QuickBASIC supplement of the

manual, Section Four A, contains additional examples.

Installing the Software

The term boot disk refers to the hard disk or floppy disk that contains

DOS and that is read by your computer when it is booted. The term

boot refers to the action of loading DOS into your system from your boot

disk, either when power is applied or when the warm boot keys are

pressed.

Step 1 - Preparation

Your first step is determined by whether you wish to boot from a floppy

disk or a hard disk. Perform the step that applies to your system.

Booting from a Floppy Disk

If you boot DOS from a floppy diskette, you need a boot disk with

enough free space to hold a copy of the GPIB-PC software contained on

the distribution diskette.

Insert the boot diskette into the first drive (usually named A:) and the

distribution diskette into the second drive (B:). Boot your system if you

have not already done so.

Booting from a Hard Disk

If you boot DOS from a hard disk, you need a personal computer with

one floppy drive. The hard disk must have enough free space to hold a

copy of the GPIB-PC software contained on the distribution diskette.

Boot your system. Then, insert the distribution diskette into the floppy

drive.

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Installation and Configuration

Section Two

Step 2 - Run IBSTART

Run IBSTARTfrom the distribution diskette by switching to the drive

containing the distribution diskette and entering:

ibstart x:

replacing x with the letter of the boot drive. For example, if the

distribution diskette is in drive Band you have booted from drive A,

enter:

to switch to drive B. Next, enter:

ibstart a:

to run IBSTART.

IBSTART first creates a directory called GPIB-PC on the boot diskette,

and copies the GPIB software to that directory. If the insufficient

disk spacemessage appears, abort the IBSTARTprogram by

pressing the control key while you enter:

Increase the free space in your boot area and run IBSTART again.

Next, IBSTARTcreates or modifies the DOS system configuration file

CONFIG.SYSto contain the line:

DEVICE=GPIB.COM

By reading this file at boot time, DOS installs new device drivers and

handlers.

Next, IBSTARTswitches to the boot drive to run the hardware

diagnostic program, IBDIAG.

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Section Two

Installation and Configuration

Finally, IBSTART advises you to complete the following actions:

•

Run IBCONFif you must reconfigure the software;

Reboot your system to load the handler into DOS; and

Run IBTESTto test the installation of the software.

Step 3 - Run IBCONF(optional)

The pamphlet Getting Started with your GPIB-PC that comes with your

interface board explains when you must run IBCONFto reconfigure the

software. You may also run IBCONFto examine how the software is

configured.

See More About IBCONFlater in this section for information on how to

run IBCONFand on the configurable software parameters.

NOTE: You must run IBCONFif you have a PCIIA, or wish to change

defaults.

Step 4 - Reboot

Reboot your computer from the drive you specified when you ran

IBSTARTso that DOS will load the GPIB-PC handler.

Step 5 - Test Software Installation

Run IBTESTfrom the directory GPIB-PC in your boot area by entering:

cd gpib-pc

ibtest

IBTESTtests whether the handler is installed and functioning with the

GPIB-PC.

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Installation and Configuration

Section Two

If errors occur, check the following:

•

Did you read Getting Started with your GPIB-PC and make any

required changes? If not, do so now.

•

Did you change hardware switch settings on your GPIB-PC

board? If so, run IBCONF and accurately input the new settings

for the board.

•

Are the GPIB.COMand CONFIG.SYSfiles installed in the root

directory of your boot drive? If not, check and repeat the

installation instructions.

Did you reboot your system before you ran IBTEST? If not, do

so now.

If you have performed these steps and IBTESTstill fails, carefully note

all error information and call National Instruments.

If no errors occur, proceed to the end of this section to learn how to use

the software and to develop your application program.

More About IBCONF

IBCONF is a screen-oriented, interactive program that is included on the

distribution diskette of the GPIB-PC package.

You use IBCONF to edit the description in the handler of characteristics

of the devices and boards in the system. Running IBCONFto place this

information directly in the handler eliminates the need to restate it

inside each application program.

IBCONFpasses two groups of features to the handler. The first group

consists of the characteristics of the instruments or devices attached to

your GPIB-PC. The second group consists of the characteristics of each

GPIB-PC installed in the computer.

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Section Two

Installation and Configuration

Characteristics of the Instruments

Each instrument used with the GPIB-PC has the following

characteristics:

•

A symbolic name of each device on the GPIB (such as DEV5or

PS5010).

•

A GPIB-PC access board for each device (e.g., GPIB0). The

access board is discussed in Device Map Concepts and Terms

later in this section.

•

A primary and, if used, secondary address for each device.

A time limit that is to be imposed when executing certain

functions. This is to ensure that accessing a powered-off device

does not hang up the GPIB indefinitely.

•

A way to terminate I/O transmissions to and from the device.

Some devices require or append an end-of-string character, such

as the ASCII line feed character, to data strings. Others use the

GPIB END message, which is sent or received via the EOI

signal line. Still others use both. Some terminate messages

only when a predetermined number of bytes are sent or

received.

Characteristics of each GPIB-PC

Each GPIB-PC has the following characteristics:

•

A symbolic name (such as GPIB0and GPIB1).

A computer I/O or port address.

The capability to be designated as the System Controller of the

devices on its bus.

•

A time limit that is imposed when executing certain functions.

A way to terminate I/O transmissions to and from the board

when executing board calls, i.e., by an end-of-string character,

an END message, and/or a byte count.

•

An interrupt level that the board uses.

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Installation and Configuration

Section Two

•

What DMA channel, if any, the board uses.

Whether it uses high-speed or normal timing when transmitting

data to a device. With normal timing, there is a delay of at

least 2 µsec after the data is placed on the GPIB before the

Data Valid (DAV) line is asserted. With high-speed timing,

this delay is decreased to about 500 nsec.

•

The Internal Clock Frequency for a PC-IIA. This is the value of

the internal PC bus clock.

Default Configurations

Just as the hardware has factory default settings for switches and

jumpers, the software also has factory default configurations. For

example, the default device names of the 16 GPIB devices are DEV1

through DEV16, but you might wish to assign more descriptive names to

each device, such as METER for a digital multimeter.

You can also use IBCONFto look at the current default settings in the

handler file.

If you do not make changes using IBCONF, the default characteristics of

the software remain in effect.

Primary Default Characteristics

The following are the primary default characteristics of the handler.

•

There are 16 active devices with symbolic names DEV1 through

DEV16.

GPIB addresses of these devices are the same as the device

number; for example, DEV1is at address 1.

The 16 devices are assigned to GPIB0 as their access board.

GPIB0is the symbolic name of the first GPIB-PC board in your

system. If you have an additional GPIB-PC in your system, its

symbolic name is GPIB1.

•

Each GPIB-PC is System Controller of its independent bus and

has a GPIB address of 0.

The END message is sent with the last byte of each data

message to a device. Each data message that is read from a

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Section Two

Installation and Configuration

device is automatically terminated when END is received. No

end-of-string character is recognized.

•

The time limit on I/O and wait function calls is approximately

10 seconds.

• GPIB0is a Model GPIB-PCII, is at base I/O address hex 02B8,

and uses DMA Channel 1 and TLC Interrupt Line 7.

•

You must run IBCONFif you are using a GPIB-PCIIA or if you

have changed the hardware switches/jumpers on any GPIB-PC

from the factory settings. Otherwise, it is unnecessary to run

IBCONF. Consult the appropriate supplement to Section Two

of the user manual to find the factory settings of your GPIB-PC

model.

Running IBCONF

When you ran IBSTART, a copy of IBCONF.EXEwas placed on your

boot drive.

To run IBCONF, go to the root directory of the boot drive and enter:

ibconf

If you have a color monitor, the configuration program will

automatically appear in color. If you have a color monitor but want the

configuration program to appear in monochrome, enter:

ibconf -m

IBCONFscans the handler file, GPIB.COM, and reads its data structures

into memory. After you press a key, the program displays the Device

Map for board GPIB0.

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Section Two

IBCONFmakes changes to the GPIB.COMfile, which should also be in

the root directory. If you want IBCONFto make changes to a different

copy of GPIB.COMsuch as GPIB2.COM, enter the path and name of

the GPIB.COMfile you want modified:

ibconf c:\GPIB-PC\GPIB2.COM

This will have the effect of changing the parameters within the

GPIB2.COMfile in the GPIB-PCsubdirectory.

Modify only the copy of GPIB.COMcreated by IBSTARTin your boot

directory. Never modify the master copy on the distribution diskette.

This would happen if you ran IBCONFfrom the distribution diskette and

if the distribution diskette were not write-protected.

Upper and Lower Levels of IBCONF

IBCONFoperates at both an upper and a lower level. The upper level

consists of the Device Maps and gives an overview of the GPIB system

as defined within the handler being configured. The lower level consists

of screens that describe each individual board and device in the system.

Upper Level - Device Map for Board GPIBx

This screen displays the names of all devices defined in the handler file,

and indicates which devices, if any, are accessed through the interface

board GPIBx. At this level, you may:

•

Rename a device;

Disconnect a device from its assigned GPIB-PC access board or

connect (reassign) it to a different access board; or

•

Proceed to the lower level to edit or examine the

characteristics of a particular board or device.

Instructions are given on the screen for selecting the individual devices

and for changing from one device map to another, for example, from the

map for GPIB0to that for GPIB1.

GPIB-PC User Manual

2-10

©National Instruments Corp.

Section Two

Installation and Configuration

Device Map Concepts and Terms

•

Device Name - contains up to seven characters. The rules for

naming devices are the same as DOS rules for naming files,

except that suffixes (.xxx) are not allowed. DOS treats

uppercase and lowercase letters identically. The string

"PLOTTER"is treated the same as the string "plotter". For

this reason, the configuration program maps all lowercase

letters to uppercase.

Device names must not be given the same names as files,

directories, and/or subdirectories. If you name a device PLTR

and your file system already contains the file PLTR.DATor a

subdirectory PLTR, a conflict results.

•

Access Board - all devices on the GPIB require an access board

within the computer. The access board is the GPIB-PC

interface board that provides the hardware link to the computer.

The access board name is of the form GPIBx, where xis a

digit 0 or 1 representing the appropriate GPIB board number.

The access board name is not alterable.

The string representing a device or board name is the first

variable argument of the function IBFINDcalled at the

beginning of your application program. Refer to Sections Three

and Four for detailed explanations of IBFIND.

Lower Level - Device/Board Characteristics

The lower level screens display the currently defined values for

characteristics such as addressing and timeout information of a device

or board. Instructions are available on the screen for selecting a specific

field and for modifying the current settings. The configuration settings

selected for each device and each board are a means of customizing the

communications and other options to be used with that board or device.

The settings for devices specify the characteristics to be used by the

access board for that device when device functions are used.

The settings for boards specify the characteristics to be used with each

board when board functions are used. In the following explanations of

device and board characteristics, notice that some characteristics apply

to both devices and boards and some apply only to boards.

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Device and Board Characteristics

Primary GPIB Address

Section Two

Each device and board must be assigned a unique primary address in the

range hex 00 to hex 1E. A listen address is formed by adding hex 20 to

the primary address; the talk address is formed by adding hex 40 to the

primary address. Consequently, a primary address of hex 10 corresponds

to a listen address of hex 30 and a talk address of hex 50. The GPIB

primary address of any device is set within that device, either with

hardware switches, or, in some cases, a software program. This address

and the address listed in IBCONFmust be the same. Refer to the

device-specific documentation provided with your instrument for

instructions about that device's address. The primary GPIB address of

all GPIB-PC boards is 0, unless changed by IBCONF. There are no

hardware switches on the GPIB-PC to select the GPIB address.

Secondary GPIB Address

Any device or board using extended addressing must be assigned a

secondary address in the range hex 60 to hex 7E, or the option NONE

may be selected to disable secondary addressing. As with primary

addressing, the secondary GPIB address of any device is set within that

device, either with hardware switches, or, in some cases, a software

program. This address and the address listed in IBCONFmust be the

same. Refer to the device documentation for instructions. Secondary

addressing is disabled for all devices and boards unless changed by

IBCONF.

Timeout Settings

The timeout value is the approximate length of time that may elapse

before I/O functions such as IBRD, IBWRT, and IBCMDcomplete. It is

also the length of time that the IBWAIT function waits for an event

before returning if the TIMO bit is set. Consequently, a wait for the

SRQ line to be asserted will terminate after the time limit is reached if

both the SRQI and TIMO bits are set in the mask passed to IBWAIT,

and no SRQ signal is detected. Refer to the IBWAIT function

description in Sections Three and Four for more information.

GPIB-PC User Manual

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©National Instruments Corp.

Section Two

Installation and Configuration

This field is set to a code mnemonic which specifies the time limit as

follows:

Table 2.1 - Timeout Settings

Code

Actual Value

Minimum Timeout

disabled

10 µsec

30 µsec

100 µsec

300 µsec

1 msec

TNONE

T10µsec

T30µsec

T100µsec

T300µsec

T1msec

T3msec

T10msec

T30msec

T100msec

T300

T1sec

T3sec

T10sec

T30sec

T100sec

T300sec

T1000sec

3 msec

10 msec

30 msec

100 msec

300 msec

1 sec

3 sec

10 sec

30 sec

100 sec

300 sec

1000 sec

NOTE: If you select TNONE, no limit will be in effect.

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Section Two

EOS Byte

Some devices can be programmed to terminate a read operation when a

selected character is detected. A linefeed character (hex 0A) is a

popular one.

NOTE: To send the EOS character to a device in a write operation, you

must explicitly include that byte in your data string.

EOS Modes

•

Terminate a Read on EOS - Some devices send an EOS byte

signaling the last byte of a data message. A yes response will

cause the GPIB-PC to terminate read operations when it

receives the EOS byte.

•

Set EOI with EOS on Write - A yes response will cause the

GPIB-PC to assert the EOI (send END) line when the EOS

character is sent.

7- or 8-bit compare on EOS - Along with the designation of an

EOS character, you may specify whether all eight bits are

compared to detect EOS, or just the seven least significant bits

(ASCII or ISO format).

Set EOI with last byte of Write

Some devices, as Listeners, require that the Talker terminate a data

message by asserting the EOI signal line (sending END) with the last

byte. A yes response will cause the GPIB-PC to assert EOI on the last

data byte.

GPIB-PC Model

The GPIB-PC Model must be specified so that the handler will use the

appropriate hardware addressing scheme.

Board is System Controller (Boards Only)

This field appears on the board characteristics screen only. Generally,

the GPIB-PC will be the System Controller. In some situations, such as

in a network of computers linked by the GPIB, another device may be

System Controller and the GPIB-PC will NOT be designated System

Controller. A yes response designates the GPIB-PC to be System

Controller. A no response designates it not to be System Controller.

GPIB-PC User Manual

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©National Instruments Corp.

Section Two

Installation and Configuration

Local Lockout on all Devices (Boards Only)

It is desirable to place many devices in the local lockout state while

they are being remotely accessed. If yes is selected, the access board

will place all of its devices in local lockout state while accessing them.

Disable Auto Serial Polling (Boards Only)

This option allows you to disable automatic serial polls if this feature is

incompatible with certain devices on the bus. While this feature is on,

the handler conducts serial polls of the devices and stores positive

responses whenever the GPIB Service request (SRQ) line is asserted.

Refer to Automatic Serial Polling of Section Four for further information.

Normally, this feature will not conflict with devices that conform to the

IEEE-488 specification.

High-Speed Timing (Boards Only)

Some devices are unable to read data messages at high-speed (Tri-

state) timing. If your GPIB system has slower devices, you may want to

select a longer data setting time by selecting no for this field.

Interrupt Jumper Setting (Boards Only)

This field must be set to the same value as the interrupt level jumper

setting on the GPIB-PC board itself. For most personal computers, this

jumper setting reflects the actual interrupt level selected. Any

exception is explained in the Getting Started with your GPIB-PC

pamphlet that comes with the interface board. Any valid interrupt level

may be selected, provided the level does not conflict with other

equipment.

Base I/O Address (Boards Only)

The GPIB-PC may be assigned any one of the legal base I/O or port

addresses as described in the appropriate supplement to this section.

The value entered must match the hardware setting selected during

hardware configuration. If it does not match, the handler cannot

communicate with the GPIB-PC.

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Installation and Configuration

Section Two

DMA Channel (Boards Only)

This field appears only on computers supporting DMA capability. The

GPIB-PC may use any of the three DMA channels, 1, 2, or 3, provided

that another device is not already using that channel. If a DMA channel

is not available, programmed I/O can be enabled by selecting NONE.

Internal Clock Frequency (Boards Only)

For the GPIB-PCII, this value is equal to the frequency of the PC bus

signal OSC divided by 2 and rounded up. Since OSC is fixed at 14.14

MHz for all IBM PCs and compatibles, this field is always set to 8.

For the GPIB-PCIIA, this value is equal to the frequency of the PC bus

signal CLK and rounded up. Since the signal CLK varies according to

the machine, this field varies as well. Typical examples are:

Machine

PCII ICF value PCIIA ICF value

IBM PC, XT, and compatibles

IBM XT (new)

IBM AT and compatibles

Compaq Deskpro

Compaq Deskpro 286

Compaq Portable 286

5,8

6,8

Notice that on some computers the CLK frequency depends on whether

the CPU is operated at normal or high-speed mode. If you want to

operate the GPIB-PC under both modes, either reconfigure the software

or use the higher value. If you are in doubt as to what value to enter,

use 8.

Exiting IBCONF

Once all changes have been made, you may exit IBCONF by typing the

function key indicated on the screen. The program will first ask if it

should save any changes before exiting. Typing a y response causes the

changes to be written to the file on disk. Before exiting, the program

will check for situations that may cause problems.

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Section Two

Installation and Configuration

Situations which are checked are as follows:

•

GPIB addressing conflict between a device and its access

board;

GPIB boards not present in the host machine at the specified

address; and

Timeouts disabled on a device or board.

If any of these situations is encountered, you will be notified and given

the option of re-entering or exiting IBCONF. To disable auto-checking,

call IBCONF -E.

After exiting, the system MUST be rebooted for the new values to take

effect.

Some functions may be called during the execution of an application

program to change some of the configured values temporarily. These

functions are shown in Table 2.2.

Table 2.2 - Functions that Alter Default Characteristics

Characteristic

Primary GPIB address

Dynamically Changed by

IBPAD

Secondary GPIB address

End-of-string (EOS) byte

7- or 8- bit compare on EOS

Set EOI with EOS on Write

Terminate a Read on EOS

Set EOI w/last byte of Write

Change board assignment

Enable or disable DMA

Change or disable time limit

Request/release system control

IBSAD

IBEOS

IBEOT

IBBNA

IBDMA

IBTMO

IBRSC

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Installation and Configuration

Section Two

Using Your GPIB-PC

Now that your software and hardware are installed, read Section Three

for an introduction to the functions available for the GPIB-PC. The

functions are described in the order that you will most likely use them.

Pay special attention to Group I, Group II, and Group III.

After reading about these functions, practice using them with your

programmable instrument or device in an interactive environment using

the IBICprogram described in Section Five. IBICallows you to

program your instrument interactively from the computer keyboard rather

than from an application program. This helps you understand how the

device and the handler work. It also familiarizes you with status

information that is returned by each function and that is also available

to your application program in the form of global variables.

While running IBIC, study the descriptions of each function given in

Section Four to fully understand the purpose and syntax of each

function.

Finally, referring to the appropriate language supplement of Section

Four, write your application program. Whenever possible, use IBICto

test the sequence of the GPIB-PC function calls your application

program makes. Trying your function calls from IBICis especially

helpful if your application program responds in an unexpected manner.

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©National Instruments Corp.

Section Three - GPIB-PC

Functions — Introduction

This section introduces you to the GPIB-PC handler functions and their

capabilities. They are described in the order you will most likely use

them.

Application environments for which the functions are designed are

described. Short examples illustrate how the functions operate.

Introduction to the GPIB-PC Functions

The GPIB-PC functions are high-level and low-level functions that

communicate with and control devices on the GPIB. The functions are

divided into six groups, and each group is distinguished by the type of

applications it serves. The functions contained in the first three groups

are mostly high-level, while those of the last three are mostly low-level.

High-Level Functions

High-level functions are easy to learn and use. They automatically

execute sequences of commands that handle bus management

operations required to perform activities such as reading from and

writing to devices and polling them for status. These functions free you

from having to know the GPIB protocol or bus management details

involved. Most device functions (functions that specify a device) are

high-level functions.

Low-Level Functions

In contrast, low-level functions perform rudimentary or primitive

operations that require that you know something about GPIB protocol to

use them effectively. They are needed because high-level functions do

not always meet the requirements of applications. In such cases, low-

level functions offer the flexibility you need to solve most of your

application problems. All board functions (functions that specify a

board) are low-level functions.

Calling Syntax

The calling syntax for GPIB-PC functions varies according to the

language used. In this section, a generic syntax is used to identify the

function and its arguments.

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GPIB-PC Functions — Introduction

Section Three

Group I

Group I functions may be the only functions you need for many of your

instrument control applications. Group I functions are as follows:

• IBRD,

• IBWRT, and

• IBFIND.

They are suitable for your applications under the following conditions:

•

Communication is between the Controller (computer) and one

device at a time. Messages are not broadcast to several

devices at once, and devices do not talk to each other directly.

Devices do not require special services or operations, such as

polling or triggering, to send or receive data.

IBRDand IBWRTare high-level input/output (I/O) functions. IBFIND

is a start-up function that opens the device.

IBRD (bd,buf,cnt)

IBRD reads a specified number of bytes from a device and stores them

in memory. The device is automatically addressed before reading and

unaddressed afterward. If not done previously, the GPIB is initialized on

entering the function and the device is placed in remote programming

mode.

When programming in BASIC, IBRDperforms string transfers. IBRDI

is available for binary transfers to an integer array.

IBWRT (bd,buf,cnt)

IBWRTwrites a specified number of bytes from the memory buffer to a

device. The device is automatically addressed before writing and

unaddressed afterward. If not done previously, the GPIB is initialized on

entering the function, and the device is placed in remote programming

mode.

When programming in BASIC, IBWRTperforms string transfers.

IBWRTIis available for binary transfers from an integer array.

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Section Three

GPIB-PC Functions — Introduction

IBFIND (bdname,bd)

IBFINDreturns a unit descriptor associated with the name of the

device. When the software is installed, a description of each device is

placed in an internal reference table accessible by the handler. This

description includes the GPIB address, end-of-string (EOS) modes,

timeout selection, and a name for the device.

Group II

Group II functions offer additional high-level device services often

needed in common instrument control applications. Group II functions

are as follows:

• IBRSP,

• IBCLR,

• IBTRG, and

• IBLOC.

IBRSP (bd,spr)

IBRSPserially polls a device and returns its status response. The

response consists of a single byte in which the hex 40 bit is set if the

device is requesting service and asserting Service Request (SRQ).

Here are examples of a Tektronix 4041 BASIC SRQ handler call and

the corresponding IBRSPcall. In this case, the device being polled is

the plotter and is at GPIB address 7:

POLL STATUS, ADDRESS; 7

CALL IBRSP (PLTR%,STATUS%)

In both cases, the plotter's status response is stored in the variable

STATUS.

Unless disabled during software configuration, any device function call

will automatically conduct serial polls if SRQ is asserted on GPIB. This

automatic serial polling is discussed in Section Four.

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GPIB-PC User Manual

GPIB-PC Functions — Introduction

Section Three

IBCLR (bd)

IBCLR clears the device by sending to it the Selected Device Clear

(SDC) and appropriate addressing commands.

Clearing the Device Versus Clearing the GPIB

There is a difference between clearing or initializing devices and

clearing or initializing the GPIB itself.

Clearing the Device

The Selected Device Clear (SDC) command that is sent by the IBCLR

function resets internal functions of the device, such as causing a digital

multimeter to change its function, range, and trigger mode back to

default settings.

Clearing the GPIB

The Interface Clear (IFC) command initializes the GPIB and the bus

interface circuits of all attached devices without affecting internal

functions. IFC is sent automatically when the first device function is

called.

A device function is a function that references a device such as the four

already described: IBRD, IBWRT, IBRSP, and IBCLR.

IBTRG (bd)

IBTRGtriggers the device by sending to it the Group Execute Trigger

(GET) and appropriate addressing commands.

IBLOC (bd)

IBLOC places the device in local program mode by sending the Go To

Local (GTL) and appropriate addressing commands to the device.

Placing a Device in Remote Mode

The first device function call after power-on, in addition to sending the

IFC command as previously described, also places the device in remote

program mode by setting the GPIB Remote Enable (REN) line and

addressing the device to listen.

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Section Three

GPIB-PC Functions — Introduction

Placing a Device in Local Mode

Devices must usually be placed in remote program mode before they

can be programmed from the GPIB. This operation is done

automatically by the handler. The IBLOCfunction is then used when

that device must be returned to local program mode.

In addition, unless disabled using the configuration program (IBCONF),

the handler places devices in local lockout mode, which prevents you

from returning a device to local mode using the device's front-panel

control.

The seven previously described functions will be sufficient to meet your

application needs, in most cases. They are the most important functions

for you to learn.

Group III

The functions of Group III are more flexible for controlling and

communicating with devices. Group III functions are as follows:

• IBRDA,

• IBWRTA,

• IBRDF,

• IBWRTF,

• IBWAIT,

• IBSTOP,

• IBTMO,

• IBONL, and

• IBPCT.

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GPIB-PC Functions — Introduction

Section Three

These functions are used under the following conditions:

•

Program execution must proceed in parallel with GPIB I/O –

often called asynchronous operation.

•

I/O is to or from a file rather than a memory buffer.

Controller-In-Charge authority must be transferred to another

GPIB device.

•

The timeout value must be changed.

The handler must be reinitialized with respect to certain

devices.

IBRDA (bd,buf,cnt)and

IBWRTA (bd,buf,cnt)

These functions are similar to IBRDand IBWRT except that the

operation is asynchronous. This means that the function returns after

starting the I/O operation without waiting for it to complete.

When programming in BASIC, IBRDAand IBWRTAperform string

transfers. IBRDIAand IBWRTIAare available for transfers to and from

an integer array.

IBRDF (bd,buf,cnt)and

IBWRTF (bd,buf,cnt)

These functions are similar to IBRDand IBWRTexcept that data is read

into a file.

IBWAIT (bd,mask)

IBWAITwaits for one or more events to occur. For the IBRDAand

IBWRTAfunctions, the event to wait for is the completion of the

operation.

IBSTOP (bd)

IBSTOP aborts any asynchronous operation associated with the device.

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Section Three

GPIB-PC Functions — Introduction

IBTMO (bd,v)

IBTMO changes the time limit in which operations with the device must

complete.

IBONL (bd,v)

IBONL re-initializes the device and cancels any asynchronous I/O in

progress. All reconfigurable software parameters, such as the time limit

just discussed, are reset to their power-on values. See the discussion of

software configuration in Section Two for further information on

reconfigurable software parameters.

The last function in this group allows the computer to pass control to

another device capable of being the Controller.

IBPCT (bd)

IBPCT passes Controller-In-Charge authority to the specified device by

sending the Take Control (TCT) commands and appropriate addressing

commands.

Most GPIB-compatible instruments or other types of devices can be

programmed using the high-level functions of Groups I, II, or III. Not all

devices, however, are completely compatible with the IEEE-488

specification, nor are the combinations of bus management and/or I/O

operations contained in the high-level functions suitable for all

applications.

Some operations, such as interprocessor networks and peripheral

sharing, require additional capabilities and flexibility in controlling the

GPIB. This is achieved, in part, with low-level functions that perform

single GPIB activities, each with a limited scope or objective. Powerful

and versatile routines can be developed using these functions. Groups

IV, V, and VI consist mostly of low-level functions.

©National Instruments Corp.

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GPIB-PC User Manual

GPIB-PC Functions — Introduction

Section Three

Group IV

The functions described previously have been device functions; that is,

the bd argument referred to a device on the GPIB. This section

introduces board functions, where bdrefers to a specific GPIB-PC

interface board in the computer. Group IV functions are as follows:

• IBFIND,

• IBCMD,

• IBCMDA,

• IBRD,

• IBRDA,

• IBWRT,

• IBWRTA,

• IBSTOP,

• IBWAIT,

• IBTMO,

• IBONL,

• IBSIC,

• IBSRE,

• IBGTS,

• IBCAC,

• IBRPP, and

• IBPPC.

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Section Three

GPIB-PC Functions — Introduction

Group IV functions can be used under the following conditions:

•

Messages are broadcast to more than one device at a time.

Messages are sent directly from one device to another, without

passing through the Controller.

•

GPIB lines, such as Attention (ATN), must be turned off or on

in a particular fashion to ensure proper operation of a device.

Devices must be polled in parallel rather than in serial.

Purpose of Board Functions

The handler software can control or communicate over the GPIB only by

manipulating a GPIB-PC interface board. Remote devices are accessed

indirectly by programming the interface board to do specific things.

Device functions are selected sequences of some basic board functions.

Board functions provide the precise control of the GPIB that is needed

for special applications.

Multiboard Capability

The handler can control or manipulate more than one interface board.

This type of handler is commonly called a multiboard handler, as

opposed to a single board handler in which one copy of the handler can

control only one board.

Figure 3.1 shows a multiboard GPIB system with board GPIB0

connected to two devices, an oscilloscope and a digital voltmeter; and

with board GPIB1connected to two other devices, a printer and a

plotter.

Each board is called the access board for its attached devices because

the board is used automatically by the device functions to access those

devices. More information about board and device functions is provided

in More About Device and Board Functions at the end of this section.

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GPIB-PC User Manual

GPIB-PC Functions — Introduction

Section Three

IBFIND (bdname,bd)

This is the same as the Group I function except that boards are assigned

names at configuration time in the form GPIBn, where nis a board's

decimal number (0, 1, 2, ...) within the computer. For instance, in a

system with two GPIB boards, the first is named GPIB0and the second

GPIB1.

IBCMD (bd,buf,cnt)and

IBCMDA (bd,buf,cnt)

Both functions use the specified board to write commands from memory

to the GPIB. The messages are sent synchronously using IBCMDand

asynchronously using IBCMDA. These command functions are used, for

example, to address and unaddress GPIB devices and to send interface

messages that enable and disable devices for serial and parallel polls,

that clear and trigger devices, and that lock out front panel control of

devices.

IBRD (bd,buf,cnt)and

IBRDA (bd,buf,cnt)

Both functions use the specified board to read from a device that has

already been addressed to talk (for example, by the IBCMDor IBCMDA

function). The syntax for these low-level functions is the same as their

high-level counterparts of Group I and III. The software automatically

differentiates bd descriptors that refer to devices from those that refer to

boards, and executes the read operations appropriately.

IBRDIand IBRDIAare also available in BASIC for binary transfers to

an integer array.

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©National Instruments Corp.

Section Three

GPIB-PC Functions — Introduction

Boards

Devices

GPIB

Board

Oscilloscope

One

SCOPE

GPIB

GPIB0

Digital Voltmeter

DVM

GPIB

Board

Plotter

PLTR

GPIB1

Another

GPIB

Printer

PRTR

Figure 3.1 - Multiboard GPIB System

©National Instruments Corp.

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GPIB-PC User Manual

GPIB-PC Functions — Introduction

Section Three

IBWRT (bd,buf,cnt)and

IBWRTA (bd,buf,cnt)

Both functions use the specified board to write to one or more devices

that have already been addressed to listen (for example, by the IBCMD

or IBCMDAfunction). The syntax for these low-level functions is the

same as their high-level counterparts of Group I and III. The software

automatically differentiates between bd descriptors that refer to devices

and those that refer to boards, and executes the write operations

appropriately.

IBWRTIand IBWRTIAare also available in BASIC for binary transfers

from an integer array.

IBSTOP (bd)

IBSTOPaborts any asynchronous operation associated with the board.

IBWAIT (bd,mask)

IBWAITwaits for the specified board to detect one of the events

selected in the mask bit vector to occur. These events include the

completion of asynchronous input/output (CMPL); the board becoming a

talker (TACS), listener (LACS), or Controller-In-Charge (CIC);

detection of a GPIB Service Request (SRQI); assertion of the Attention

signal (ATN); detection of the END message (END); or detection of a

time limit (TIMO) or other error condition (ERR).

IBTMO (bd,v)

IBTMO changes the time limit in which operations with the board must

complete.

IBONL (bd,v)

IBONLperforms the same initialization function for boards as the Group

III IBONLfunction does for devices. In addition, the hardware as well

as the software is reset and the board is placed online (enabled) or

offline (disabled).

IBSIC (bd)

IBSIC uses the board to initialize the GPIB by sending the Interface

Clear (IFC) message.

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©National Instruments Corp.

Section Three

GPIB-PC Functions — Introduction

IBSRE (bd,v)

IBSRE uses the board to set or clear the GPIB Remote Enable (REN)

line.

IBGTS (bd,v)

IBGTScauses the board to go from Active Controller to Standby

Controller, and in so doing to turn the ATN signal off. This function is

generally used to allow two external devices to talk to each other

directly. The board can selectively participate in the handshake of the

data transfer and hold off the handshake when the END message is

detected. The board may then take control synchronously without

corrupting the transfer.

IBCAC (bd,v)

IBCACcauses the board to take control of the GPIB by setting ATN and

going from Standby to Active Controller. The board can take control

synchronously or asynchronously.

IBRPP (bd,buf)

IBRPPconducts a parallel poll and returns the result.

IBPPC (bd,v)

IBPPCremotely configures or unconfigures the devices for parallel

polls.

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GPIB-PC User Manual

GPIB-PC Functions — Introduction

Section Three

More About Device and Board Functions

Before proceeding to the next group of functions, you will find it helpful

to compare how a high-level device function can be replaced by several

low-level board functions. Conducting a serial poll is a good example.

In the discussion of the IBRSPfunction of Group II, this BASIC

example of the device function was used:

CALL IBRSP (PLTR%,STATUS%)

This is equivalent to the following sequence using the board functions

just described:

CMD$ = "?" + CHR$(&H18) + "G!"

CALL IBCMD (GPIB0%,CMD$)

STATUS$ = SPACE$(1)

CALL IBRD (GPIB0%,STATUS$)

CMD$ = "_?" + CHR$(&H19)

CALL IBCMD (GPIB0%,CMD$)

The first IBCMDfunction is used to send the string of ASCII commands

assigned in the first program line. These are Unlisten (?), Serial Poll

Enable (CHR$(&H18)), talk address of the plotter (G), and listen

address of the board (!). Now that the plotter is enabled to send its

status byte and the board is addressed to receive it, the IBRD function is

called to read the byte and store it in the variable STATUS. The final

IBCMD function completes the poll by sending the command string

consisting of three messages: Untalk (_), Unlisten (?), and Serial Poll

Disable (CHR$(&H19)).

You can see that a high-level device function is easier to use. However,

when an application requires a more complex serial poll routine than the

one just described, such as a serial poll routine which polls several

devices in succession and provides other servicing operations at the

same time, low-level board functions can be used to create such a

routine.

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©National Instruments Corp.

Section Three

GPIB-PC Functions — Introduction

Group V

Group V functions are used when the GPIB-PC is not CIC. An example

is a system where the computer in which the board is installed performs

as an instrument, but is controlled by another device on the GPIB.

Group V functions are as follows:

• IBRSV,

• IBLOC,

• IBPPC,

• IBIST, and

• IBWAIT.

These functions are used to:

•

Request service from the CIC.

Simulate a front panel "return to local" switch.

Reconfigure a board or device for a parallel poll.

Locally configure for parallel polls and change the parallel poll

flag.

•

Wait for the CIC to execute certain actions.

IBRSV (bd,v)

IBRSV requests service from the CIC and to set the status byte that is

sent when the board is serially polled by the controller.

IBLOC (bd)

IBLOC sends a return to local message to the board. The message

clears an internal remote status condition if it is set and the internal

lockout status condition is not set. These conditions can be checked

with the IBWAITfunction. How the application program interprets this

action is system dependent.

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GPIB-PC Functions — Introduction

Section Three

IBPPC (bd,v)

IBPPClocally configures or unconfigures the board for parallel polls.

IBIST (bd,v)

IBIST sets or clears the board's parallel poll flag (also known as the

individual status bit).

IBWAIT (bd,mask)

This function is described in Group IV. It is included here to describe

the additional events associated with noncontroller operations that the

function can detect. These include being triggered (DTAS) or cleared

(DCAS) by the controller, being placed in remote programming mode

(REM) by the controller, or being placed in a lockout state (LOK) by

the controller.

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©National Instruments Corp.

Section Three

GPIB-PC Functions — Introduction

Group VI

Group VI functions are used only when the default values of the

configuration parameters set during software installation need to be

changed dynamically or temporarily during execution of the application

program. Group VI functions are as follows:

• IBEOT,

• IBEOS,

• IBBNA,

• IBDMA,

• IBPAD,

• IBSAD,

• IBRSC, and

• IBTMO.

They are used to accomplish the following actions:

•

Change the way I/O transmissions are terminated.

Associate a device with a different access board.

Change from DMA to programmed I/O.

Change the GPIB address of a board or device.

Request or release System Control.

IBEOT (bd,v)

IBEOT enables or disables sending the END message (EOI) with the

last byte written by the board.

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GPIB-PC Functions — Introduction

Section Three

IBEOS (bd,v)

IBEOSassigns the end of string (EOS) character to use with subsequent

IBRDand IBWRToperations. This character is compared with incoming

bytes from the device and may be used to terminate a read operation. It

is also compared with outgoing bytes to the device and may be used to

generate the END message (EOI).

IBBNA (bd,"GPIBn")

IBBNAassigns board n to be the access board for device bd.

IBDMA (bd,v)

IBDMAselects DMA or programmed I/O for the board. This function is

only appropriate for boards with DMA capability.

IBPAD (bd,v)

IBPADsets the primary GPIB address of the device or board.

IBSAD (bd,v)

IBSADsets the board's or device's secondary GPIB address or disables

secondary addressing.

IBRSC (bd,v)

IBRSC causes the board to request or release System Control authority.

IBTMO (bd,v)

IBTMO sets the time limit in which operations with a device or board

must complete.

Another important feature of the GPIB-PC functions is that they return

status information about the boards and devices in the system. This

information is returned in the form of three global status variables,

IBSTA, IBERR, and IBCNT. The beginning of Section Four fully

describes these variables.

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©National Instruments Corp.

Section Four - GPIB-PC

Functions — Overview

This section consists of Section Four and a BASIC supplement. Section

Four contains a discussion of the important characteristics common to

all programming languages. The BASIC supplement lists the GPIB

functions for BASICA and QuickBASIC languages.

When you order a language other than BASIC, you receive a separate

supplement unless your language is very similar to BASICA. Insert any

new supplements in place of or in addition to Section Four A.

General Programming Information

The following characteristics are common to all programming

languages:

•

A Status Word,

Error Codes,

A Count Variable,

Read and Write Termination,

Device Function Calls, and

Automatic Serial Polling.

A thorough understanding of the concepts presented here is essential to

the implementation of a GPIB system.

The next several paragraphs explain the status word (IBSTA), the error

variable (IBERR), and the count variable (IBCNT). These variables are

updated with each function call to reflect the status of the most recently

referenced device or board.

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GPIB-PC Functions — Overview

Section Four

Status Word

All functions return a status word containing information about the state

of the GPIB and the GPIB-PC. You should test for the conditions

reported in the status word to make decisions about continued

processing. The status word is returned in the variable IBSTA.

The status word contains 16 bits, of which 14 are meaningful. A bit

value of 1 indicates the corresponding condition is in effect. A bit value

of zero indicates the condition is not in effect.

Table 4.1 lists the conditions and the bit position to be tested for that

condition. Some bits are set only on device function calls (d); some

bits are set only on board function calls (b); and some bits are set on

either type (db).

Table 4.1 - Status Word Layout

Mnemonics Bit

Hex

Function Description

Type

Pos. Value

ERR

TIMO

END

SRQI

RQS

8000

4000

2000

1000

800

GPIB error

Time limit exceeded

END or EOS detected

SRQ interrupt received

Device requesting

service

CMPL

LOK

REM

CIC

100

I/O completed

Lockout State

Remote State

Controller-In-Charge

Attention is asserted

Talker

Listener

Device Trigger State

Device Clear State

ATN

TACS

LACS

DTAS

DCAS

A description of each status word and its condition follows.

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Section Four

GPIB-PC Functions — Overview

ERR (db) ERR is set in the status word following any call that results

in an error; the particular error may be determined by

examining the IBERR variable. It is cleared following any

call that does not result in an error.

NOTE: Always check for an error condition after each call.

An error made early in your application program may not

become apparent until a later instruction. At that time, the

error can be more difficult to locate.

TIMO (db) TIMO specifies whether a timeout has occurred. It is set in

the status word following a call to IBWAITif the TIMO bit

of the IBWAITmaskparameter is also set and if the wait

has exceeded the time limit value that is set by the IBTMO

call. It is also set following a call to any of the synchronous

I/O functions (e.g., IBRD, IBWRT, and IBCMD) if a timeout

occurs during a call. TIMO is cleared in the status word in

all other circumstances.

END (db) END specifies whether the END or EOS message has been

received. It is set in the status word following a read

function if the END or EOS message was detected during

the read. While the GPIB-PC is performing a shadow

handshake as a result of the IBGTS function, any other

function call may return a status word with the END bit set

if the END or EOS message occurred before or during that

call. It is cleared in the status word when any I/O operation

is initiated.

SRQI (b) SRQI specifies whether a device is requesting service. It is

set in the status word whenever the GPIB-PC is CIC and

the GPIB SRQ line is asserted. It is cleared whenever the

GPIB-PC ceases to be the CIC, or the GPIB SRQ line is

unasserted. The bit is also cleared when executing board

functions and the GPIB-PC is an active talker, i.e., it is

addressed to talk and ATN is unasserted.

In Revision D software, the SRQI status bit always reflects

the current level of the SRQ line whether or not the GPIB-

PC is CIC.

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GPIB-PC Functions — Overview

RQS (d)

Section Four

RQS appears only in the status word of a device function

call. Indicates that the device is requesting service. It is

set in the status word whenever the hex 40 bit is asserted in

the device's serial poll status byte. The serial poll which

obtains the status byte may be the result of an IBRSP call,

or it may be done automatically by the handler. It is

cleared when the user has called IBRSP to read the serial

poll status byte that caused the RQS. An IBWAITon RQS

should only be done on devices that respond to serial polls.

CMPL (db) CMPL specifies the condition of outstanding I/O operations.

It is set in the status word whenever I/O is not in progress;

that is, whenever I/O is complete. It is cleared while I/O is

in progress.

LOK (b)

LOK specifies whether the board is in a lockout state.

While LOK is set, the function IBLOC is effectively

inoperative for that board. It is set whenever the GPIB-PC

detects the Local Lockout (LLO) message has been sent

either by the GPIB-PC or by another Controller. It is

cleared when the Remote Enable (REN) GPIB line

becomes unasserted either by the GPIB-PC or by another

Controller.

REM (b)

REM specifies whether the board is in remote state. It is

set whenever the Remote Enable (REN) GPIB line is

asserted and the GPIB-PC detects its listen address has

been sent either by the GPIB-PC or by another Controller.

It is cleared whenever REN becomes unasserted, or when

the GPIB-PC as a Listener detects the Go to Local (GTL)

command has been sent either by the GPIB-PC or by

another Controller, or when the IBLOCfunction is called

while the LOK bit is cleared in the status word.

CIC (b)

CIC specifies whether the GPIB-PC is the Controller-In-

Charge. It is set whenever the IBSIC function is called

while the GPIB-PC is System Controller, or when another

Controller passes control to the GPIB-PC. It is cleared

whenever the GPIB-PC detects Interface Clear (IFC) from

the System Controller, or when the GPIB-PC passes control

to another device.

ATN (b)

ATN specifies the state of the GPIB Attention (ATN) line.

It is set whenever the GPIB ATN line is asserted and

cleared when the ATN line is unasserted.

TACS (b) TACS specifies whether the GPIB-PC has been addressed

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Section Four

GPIB-PC Functions — Overview

as a Talker. It is sent either by the GPIB-PC itself or by

another Controller. It is cleared whenever the GPIB-PC

detects the Untalk (UNT) command, a talk address other

than its own talk address, or Interface Clear (IFC).

LACS (b) LACS specifies whether the GPIB-PC has been addressed

as a Listener. It is set whenever the GPIB-PC detects its

listen address (and secondary address, if enabled) has been

sent either by the GPIB-PC itself or by another Controller.

It is also set whenever the GPIB-PC shadow handshakes as

a result of the IBGTSfunction. It is cleared whenever the

GPIB-PC detects the Unlisten (UNL) command, its own

talk address, Interface Clear (IFC), or IBGTS is called

without shadow handshake.

DTAS (b) DTAS specifies whether the GPIB-PC has detected a

device trigger command. It is set whenever the GPIB-PC,

as a Listener, detects the Group Execute Trigger (GET)

command has been sent by another Controller. It is cleared

in the status word on any call immediately following an

IBWAITcall if the DTAS bit is set in the IBWAITmask

parameter.

DCAS (b) DCAS specifies whether the GPIB-PC has detected a

device clear command. It is set whenever the GPIB-PC

detects the Device Clear (DCL) command has been sent

by another Controller, or whenever the GPIB-PC as a

Listener detects the Selected Device Clear (SDC)

command has been sent by another Controller. It is cleared

in the status word on any call immediately following an

IBWAITcall if the DCAS bit was set in the IBWAITmask

parameter, or on any call immediately following a read or

write.

In addition to the above, the following situations also affect the status

word bits:

•

A call to the function IBONL clears the following bits:

END LOK REM CIC TACS LACS DTAS DCAS

•

A call to IBONL affects bits other than those listed here

according to the rules explained above.

In the event that a function call returns an ENEB or EDVR error, all

status word bits except the ERR bit are cleared, since these error codes

indicate that it is not possible to obtain the status of the GPIB-PC.

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GPIB-PC Functions — Overview

Section Four

Error Codes

When the ERR bit is set in the status word, a GPIB error has occurred.

The error code is returned in the variable IBERR.

There are 14 possible error codes. Table 4.2 lists these codes, a

recommended mnemonic to be associated with that type of error, and

the numeric value of the code.

Table 4.2 - GPIB Error Codes

Suggested

Mnemonic

EDVR

ECIC

Decimal Explanation

Value

DOS error

Function requires GPIB-PC to be CIC

No Listener on write function

GPIB-PC not addressed correctly

Invalid argument to function call

GPIB-PC not System Controller as required

I/O operation aborted

ENOL

EADR

EARG

ESAC

EABO

ENEB

Non-existent GPIB-PC board

I/O started before previous operation

EOIP

completed

ECAP

EFSO

EBUS

ESTB

No capability for operation

File system error

Command error during device call

Serial Poll status byte lost

SRQ stuck in ON position

ESRQ

A description of each error and some conditions under which it may

occur follows:

EDVR (0) EDVR is returned by the language interface when the

device or board name passed in an IBFINDcall is not

configured in the handler. In this case, the variable IBCNT

will contain the DOS error code 2, "Device not found." The

remedy is to replace the argument to IBFINDwith a valid

board or device name, or reconfigure the handler using the

IBCONF utility to recognize the name.

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Section Four

GPIB-PC Functions — Overview

It is also returned when an invalid unit descriptor is passed

to any function call. In this case, the variable IBCNT will

contain the DOS error code 6, "Invalid handle." The

remedy is to be sure that IBFIND has been called and that

it returned successfully. Also note that following a call to

IBONLwith a second argument of 0, which places bd

"offline," an IBFINDis required before any subsequent

calls with that device or board.

EDVR is also returned when the handler (GPIB.COM) is

not installed. The remedy is to check the CONFIG.SYS

file in the root directory and make sure it contains the line:

DEVICE=GPIB.COM

ECIC (1) ECIC is returned when one of the following board level

calls is made while the board is not CIC of the GPIB:

• IBCMD,

• IBRPP,

• IBCAC, and

• IBGTS.

In cases when the GPIB-PC should always be the CIC, the

remedy is to be sure to call IBSIC to send Interface Clear

before attempting any of these calls, and to avoid sending

the command byte TCT (hex 09, Take Control). In

multiple CIC situations, the remedy is to always be certain

that the CIC bit appears in the status word IBSTA before

attempting these calls. If it is not, it is possible to perform

an IBWAIT (CIC) call to delay further processing until

control is passed to the board.

ENOL (2) ENOL usually occurs when a write operation was attempted

with no listeners addressed. For a device write, this error

indicates that the GPIB address configured for that device

in the handler does not match the GPIB address of any

device connected to the bus. This situation may be

corrected by either attaching the appropriate device to the

GPIB, by modifying the address of an already attached

device, by altering the switches on the device, by calling

IBPAD(and IBSAD if necessary) to make the configured

address match the device switch settings, or by using the

IBCONFconfiguration utility to reassign the proper GPIB

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GPIB-PC Functions — Overview

address to the device in the handler.

Section Four

For a board write, an IBCMD call is generally necessary to

address devices before an IBWRT. Be sure that the proper

listen address is in the IBCMD argument string and that no

Unlisten (hex 3F) command follows it.

ENOL may occur in situations in which the GPIB-PC is not

the CIC and the Controller asserts ATN before the write

call in progress has ended. The remedy is either to reduce

the write byte count to that which is expected by the

Controller, or to resolve the situation on the Controller's

end.

EADR (3) EADR occurs when the GPIB-PC is CIC and is not

addressing itself before read and write calls are made. This

error is extremely unlikely to occur on a device call. For a

board call the remedy is to be sure to send the appropriate

Talk or Listen address using IBCMDbefore attempting the

IBWRTor IBRD.

EADR is also returned by the function IBGTSwhen the

shadow-handshake feature is requested and the GPIB ATN

line is already unasserted. In this case, the shadow

handshake is not possible and the error is returned to notify

you of that fact. IBGTS should almost never be called

except immediately after an IBCMDcall. (IBCMD causes

ATN to be asserted.)

EARG (4) EARG results when an invalid argument is passed to a

function call. The following are some examples:

IBTMOcalled with a value not in the range 0-17.

IBEOS called with meaningless bits set in the high byte of

the second parameter.

IBPADor IBSADcalled with illegal addresses.

IBPPC called with illegal parallel poll configurations.

A board-only call made with a valid device descriptor, or a

device-only call made with a valid board descriptor.

(NOTE: EDVR is returned if the descriptor is invalid.)

ESAC (5) ESAC results when IBSICor IBSREis called when the

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Section Four

GPIB-PC Functions — Overview

GPIB-PC does not have System Controller capability. The

remedy is to give the GPIB-PC that capability by calling

IBRSCor by using IBCONFto configure that capability

into the handler.

EABO (6) EABO indicates that I/O has been canceled, usually due to

a timeout condition. Other causes are IBSTOP being

called or the Device Clear message being received from

the CIC.

To remedy a timeout error, if I/O is actually progressing but

times out anyway, lengthen the timeout period with IBTMO.

More frequently, however, the I/O is stuck (the Listener is

not continuing to handshake or the Talker has stopped

talking), or the byte count in the call which timed out was

more than the other device was expecting. Be sure that

both parties to the transfer understand what byte count is

expected; or if possible, have the Talker use the END

message to assist in early termination.

ENEB (7) ENEB occurs when there is no GPIB-PC at the I/O address

specified in the configuration program. This happens when

the board is not physically plugged into the system, when

the I/O address specified during configuration does not

match the actual board setting, or when there is a conflict

in the system with the BASE I/O address. If there is a

mismatch between the actual board setting and the value

specified at configuration time, either reconfigure the

software or change the board switches to match the

configured value.

EOIP (10) EOIP occurs when asynchronous I/O has not completed

before some other call was made. During asynchronous

I/O, until the CMPL bit is set in IBSTA, only IBSTOPand

IBWAITcalls are allowed. EOIP is returned when any

other call is attempted before the I/O completes. The

remedy is to use IBWAITto wait for the CMPL status and

then attempt the other call.

ECAP (11) ECAP results when a particular capability has been

disabled in the handler, and a call is made which attempts

to make use of that capability. For example, if you use

IBCONFto disable DMA for a board, and then try to call

IBDMAto turn DMA back on, you will get this error. The

remedy is not to deny capabilities which may be needed

later, and to avoid making calls which attempt to alter or

make use of capabilities that are unalterable at runtime.

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GPIB-PC Functions — Overview

Section Four

EFSO (12) EFSO results when an IBRDFor IBWRTFcall encounters a

problem performing a file operation. Specifically, this error

indicates the function was unable to open, create, seek,

write, or close the file being accessed. The specific DOS

error code for this condition is contained in IBCNT.

EBUS (14) EBUS results when certain GPIB bus errors occur during

device-level calls. It is necessary in all device calls for the

handler to send command bytes to perform addressing,

serial polls, and to send other bus management information.

Devices are expected to accept these command bytes

within the time limit specified by the configuration program

or by IBTMO. EBUS occurs if a timeout occurred during

the sending of these command bytes. Under normal

operating circumstances, the remedy would be to find out

which GPIB device is accepting commands abnormally

slowly and fix the problem with that device. In situations

in which slow handshaking of the commands is desirable,

lengthen the time limit either with the configuration

program or the IBTMOfunction.

ESTB (15) ESTB occurs only during the IBRSPcall. This indicates

that one or more serial poll status bytes which were

received due to automatic serial polls have been discarded

for lack of room to store them. Several older status bytes

are available; however, the oldest is being returned by the

IBRSP call. If an occasional lost status byte is not

important in your application, you may consider this error

code informative only and ignore it. If your application

cannot tolerate missing even one status byte, the remedy is

to disable Automatic Serial Polling using IBCONF.

ESRQ (16) ESRQ occurs only during the IBWAITcall. This indicates

that a wait for RQS is not possible because the GPIB SRQ

line is stuck on. The usual reason for this situation is that

some device that the handler is unaware of is asserting

SRQ. Since the handler does not know of this device, it

will never be serially polled and SRQ will never go away.

Another reason for the situation would be that a GPIB bus

tester or similar equipment was forcing the SRQ line to be

asserted, or that there is a cable problem involving the

SRQ line. Although the occurrence of ESRQ signals a

definite GPIB problem, it will affect no GPIB operations

whatever except that the RQS bit cannot be depended on

while the condition lasts.

GPIB-PC User Manual

4-10

©National Instruments Corp.

Section Four

GPIB-PC Functions — Overview

Count Variable

The IBCNT variable is updated after each read, write, or command

function call with the number of bytes actually transferred by the

operation.

Read and Write Termination

The IEEE-488 specification defines two methods of identifying the last

byte of device-dependent (data) messages. The two methods permit a

Talker to send data messages of any length without the Listener(s)

knowing in advance the number of bytes in the transmission. The two

methods are as follows:

•

END message. In this method, the Talker asserts the EOI (End

Or Identify) signal simultaneously with transmission of the last

data byte. By design, the Listener stops reading when it detects

a data message accompanied by EOI, regardless of the value of

the byte.

•

End-of-string (EOS) character. In this method, the Talker uses

a special character at the end of its data string. By prior

arrangement, the Listener stops receiving data when it detects

that character. Either a 7-bit ASCII character or a full 8-bit

binary byte may be used.

The methods can be used individually or in combination. However, it is

important that the Listener be properly configured to unambiguously

detect the end of a transmission.

The GPIB-PC always terminates IBRDoperations on the END message.

Using the configuration program, you can accommodate all permissible

forms of read and write termination. The default configuration settings

for read and write termination can be changed at run time using the

IBEOSand IBEOTfunctions, if necessary.

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GPIB-PC Functions — Overview

Section Four

Device Function Calls

Device functions are those functions in which the unit descriptor

identifies a device rather than an interface board. There are some

activities common to all device functions that should be understood

thoroughly.

In a single board configuration in which there is only one GPIB-PC in

use, when the first device function of the program is executed, the GPIB

is initialized by its controlling access board with the Interface Clear

(IFC) command. The Remote Enable (REN) line on that GPIB is also

asserted. If selected in the configuration program, the Local Lockout

(LLO) command is also sent to all devices on the GPIB to place them

in a lockout state. Furthermore, the device may be addressed to listen

and then unaddressed before certain functions are executed. This is to

ensure that the device is in remote program mode.

In a multiboard configuration in which there is more than one GPIB-PC,

the process is the same as previously described, with the exception that

each GPIB is initialized by its access board when the first device on

that GPIB is accessed by a device function call.

The previous descriptions assume that the GPIB-PC is the System

Controller of its GPIB, which is the usual configuration. If the GPIB-PC

is not the System Controller, it must be passed CIC authority from the

System Controller to execute device functions. If the access board is

not CIC when a device function is called, the board requests service

from the current CIC by asserting the Service Request (SRQ) line and

passing the status response byte hex 41 when serially polled by the CIC.

The handler then waits indefinitely for control to be passed to the access

board. The computer system hangs if there is not another CIC that will

pass control. This might happen, for example, if the access board is

supposed to be System Controller, but it was not configured as such

during software installation.

In Revision D software, if the access board is not CIC when the device

call is made, the ECIC error is returned.

Also in Revision D software, because of multitasking, board-level

reconfiguration functions must not be called during device-level calls.

GPIB-PC User Manual

4-12

©National Instruments Corp.

Section Four

GPIB-PC Functions — Overview

Automatic Serial Polling

If this feature is enabled, the handler automatically conducts serial polls

when SRQ is asserted. The handler polls all active devices and stores

each positive response, i.e., those responses that have the Request

Service (RQS) or hex 40 bit set in the device status byte, in a queue

associated with each device. Queues are necessary because some

devices can send multiple positive status bytes back-to-back. When a

positive response from a device is received, the RQS bit of its status

word (IBSTA) is set. The polling continues until SRQ is unasserted or

an error condition is undetected.

If the handler cannot locate the device requesting service (no known

device responds positively to the poll), or if SRQ becomes stuck on

(due to a faulty instrument or cable), then a GPIB system error exists

which will interfere with the proper evaluation of the RQS bit in the

device's status words. The error (ESRQ) will be reported to you if and

when you issue an IBWAITcall with the RQS bit included in the wait

mask. Should the error condition clear itself up, you will notice this by

calling IBWAIT with the RQS bit set in the mask, where the ESRQ

error will not be reported. Aside from the difficulty caused by this error

in waiting for RQS, the error will have no detrimental effects on other

GPIB operations.

If the serial poll function IBRSPis called and one or more responses

have been received previously via the automatic serial poll feature, then

the first queued response is returned by the IBRSPfunction in FIFO

(first in-first out) fashion. If the RQS bit of the status word is not set

when IBRSP is called, the function conducts a serial poll and returns

whatever response is received.

If your application requires that requests for service be noticed, you

should examine the RQS bit in the status word and call the IBRSP

function to examine the status byte whenever it appears. It is possible

for a device's serial poll response queue to get clogged with old status

bytes when you neglect to call IBRSPto empty the queue. This error

condition (ESTB) is returned only by IBRSPwhen it becomes

necessary to report that status bytes have been discarded due to a full

queue. If your application has no interest in SRQ or status bytes, you

may ignore the occurrence of the automatic polls. The polls occur

rarely, and the error conditions described will not occur unless you use

the feature.

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GPIB-PC Functions — Overview

Section Four

If the handler is configured with automatic serial polling enabled, this

feature will be disabled after a board-level I/O function call, and

resumed after a device-level I/O function call. However, if any device-

level I/O call results in a timeout error, this feature will be disabled

until the next I/O call completes.

NOTE: If the RQS bit of the device status word is still set after IBRSP

is called, the response byte queue has at least one more response byte

remaining. IBRSP should be called until RQS is cleared to gather all

stored response bytes and to guard against queue overflow.

GPIB-PC User Manual

4-14

©National Instruments Corp.

Section Four A -

BASICA/QuickBASIC GPIB-PC

Function Calls

This section contains information for programming the GPIB-PC in

BASICA and QuickBASIC, Versions 4.0 and earlier. The term

BASICA, as used in this section, refers to Advanced IBM Interpretive

BASIC for the IBM Personal Computer. The term QuickBASIC refers

to Microsoft QuickBASIC.

The programming information in this supplement can be used with all

versions of BASICA and QuickBASIC unless specified otherwise.

When different programming information is required that is specific to a

particular version, this information is separated and identified by a

frame with the respective version number in the upper left corner. An

example of this appears as follows:

If information is required that is specific to two versions, this

information is separated and identified by a frame with the two version

numbers in the upper left corner. An example of this appears as follows:

©National Instruments Corp.

4A-1

GPIB-PC User Manual

BASICA/QuickBASIC GPIB-PC Function Calls

Section Four A

If information is required that is specific to three versions, this

information is separated and identified by a frame with the three version

numbers in the upper left corner. An example of this appears as follows:

Information that is not located in a frame can be used to program the

GPIB-PC in all versions of BASICA and QuickBASIC (that is, Version

4.0 and earlier).

BASICA Files

The GPIB-PC distribution diskette contains four files relevant to

programming in BASICA:

• DECL.BAS- A file containing required initialization code.

• BIB.M- The BASICA language interface which gives your

application program access to the handler.

• DBSAMP.BAS- A sample program using device calls.

• BBSAMP.BAS- A sample program using board calls.

QuickBASIC Files

The GPIB-PC distribution diskette contains four files relevant to

programming in QuickBASIC. These files were copied to a subdirectory

called GPIB-PCwhen you ran the installation program IBSTART.BAT.

• QBDECL.BAS- A file containing required initialization code.

• QBIB1.OBJ- Version 1.0 language interface.

GPIB-PC User Manual

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©National Instruments Corp.

Section Four A

BASICA/QuickBASIC GPIB-PC Function Calls

• QBIB2.OBJ- Version 2.0 and 3.0 without coprocessor.

• QBIB_87.OBJ- Version 3.0 with coprocessor.

• QBIB_87E.OBJ- Version 3.0 coprocessor emulator mode.

• QBIB4.OBJ- Version 4.0 language interface..

• QBDECL4.BAS- Version 4.0 required initialization code..

The appropriate language interface depends on the version of

QuickBASIC used:

• DQBSAMP.BAS- A sample program using device calls.

• BQBSAMP.BAS- A sample program using board calls.

Programming Preparations for BASICA

A BASICA language code block must be executed before the main body

of your application program.

Place the file DECL.BAS, which contains this code block, at the

beginning of the application program, with appropriate adjustments to

line numbers. Refer to the BASICA MERGE command. DECL.BAS

contains code which loads the file BIB.Minto memory. The file

BIB.M contains the BASICA language interface to the GPIB-PC

handler, and must exist in the directory currently in use.

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BASICA/QuickBASIC GPIB-PC Function Calls

Section Four A

You may change function and variable names defined in the code block

if they conflict with names the application program is using. The

substitution must be done consistently and carefully throughout.

Instructions provided in this section assume that no name substitution is

necessary and that the recommended names are used.

The GPIB status, error, and count information is returned in the

variables IBSTA%, IBERR%, and IBCNT%as described at the beginning

of Section Four.

In accordance with BASICA language protocol, all function arguments

are variables, either integer or string, and their values must be assigned

before the function call is made.

The CLEARstatement in line 1 of DECL.BAS contains a constant which

is used to determine the memory requirements of the BASICA language

interface. For the great majority of users this constant is correct. The

constant may be incorrect, however, if you are using a system with an

extremely small amount of memory. If after BASICA is invoked it

reports that there are fewer than 60000 bytes free, you may need to

adjust the constant to a smaller value.

Programming Preparations for QuickBASIC

Include the following QuickBASIC statement at the beginning of your

application program:

COMMON SHARED IBSTA%, IBERR%, IBCNT%

This statement is included in the file QBDECL.BASon the distribution

diskette.

The GPIB status, error, and count information is returned in the

variables IBSTA%, IBERR%, and IBCNT%as described at the beginning

of Section Four.

The file QBIB*.OBJ contains the QuickBASIC language interface to

the GPIB-PC handler. Link compiled GPIB application programs

written in QuickBASIC with QBIB*.OBJto produce an executable file

permitting access to the handler.

In accordance with QuickBASIC language protocol, all function

arguments are variables, either integer or string, and their values must

be assigned before the function call is made.

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©National Instruments Corp.

Section Four A

BASICA/QuickBASIC GPIB-PC Function Calls

To run your program from within the QuickBASIC editor use the

QuickBASIC BUILDLIB command to add QBIB*.OBJto your user

library, and load that library when loading QuickBASIC. For example,

if you are already using a library called USERLIB.EXE, add

QBIB2.OBJto it by entering:

BUILDLIB USERLIB.OBJ QBIB2.OBJ;

Then to run QuickBASIC enter:

QB /L USERLIB.EXE

To run your program from within the QuickBASIC interactive

environment, use the LINK command to create a QuickLibrary. For

example, to create a QuickLibrary called QBIB4.QLB, enter:

LINK /Q QBIB4.OBJ,,,BQLB40.LIB;

Then to run QuickBASIC enter:

QB /L QBIB4.QLB

To run your program from MS DOS, follow the instructions in the

QuickBASIC User's Manual which pertain to compiling and linking

programs. Use the file QBIB4.OBJfor linking purposes.

BASICA/QuickBASIC GPIB-PC I/O Functions

The most commonly needed I/O functions are IBRDand IBWRT. In

BASICA, these functions read and write from a character string that

may be up to 255 bytes long.

In addition, integer I/O functions (IBRDIand IBWRTI) are provided for

users whose data strings are longer than 255 bytes, or who need to

©National Instruments Corp.

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BASICA/QuickBASIC GPIB-PC Function Calls

Section Four A

perform arithmetic operations on the data and want to avoid the

overhead of converting the character bytes of IBRDand IBWRTinto

integer format and back again.

IBRDIand IBWRTIare passed data in the form of an integer array,

instead of a character string whose maximum length is limited to 255

bytes. Using these functions, you may store more than 255 bytes in a

single buffer and do not have to convert each pair of data bytes to an

integer before doing arithmetic operations on the data. Internally, the

IBWRTIfunction sends each integer to the GPIB in low-byte, high-byte

order. The IBRDIfunction reads a series of data bytes from the GPIB

and stores them into the integer array in low-byte, high-byte order.

In addition to IBRDIand IBWRTI, the asynchronous functions IBRDIA

and IBWRTIAare provided to perform asynchronous integer reads and

writes.

The functions are listed alphabetically by function name in this section.

Table 4A.1 provides a summary of the BASICA GPIB-PC functions and

Table 4A.2 provides a summary of the QuickBASIC GPIB-PC functions.

BASICA/QuickBASIC "ON SRQ" Capability

BASICA programs may be interrupted on the occurrence of the GPIB

SRQ signal. When the interrupt occurs, a branch can be taken to a

service routine which determines the cause of the SRQ and takes the

appropriate action.

National Instruments uses this statement to intercept SRQ interrupt and

make them available to user programs. For more complete information

regarding the operation of "ON PEN", refer to the IBM BASICA User's

Manual and Microsoft QuickBASIC under the "ON PEN Statement."

All the information in that section applies to both the light pen and to

the GPIB SRQ signal.

Statements such as "ON PEN" which intercept interrupts are a special

feature of some versions of BASIC, including BASICA and

QuickBASIC. These statements, however, are not usually a feature of

non-BASIC languages and are not necessarily supported in other

National Instruments language interfaces. To determine if this feature is

supported in languages other than BASICA and QuickBASIC, refer to

the manual supplement that comes with that language.

GPIB-PC User Manual

4A-6

©National Instruments Corp.

Section Four A

BASICA/QuickBASIC GPIB-PC Function Calls

Table 4A.1 - BASICA GPIB-PC Functions

Description

CALL Function Syntax

IBBNA (BD%,BNAME$)

IBCAC (BD%,V%)

IBCLR (BD%)

Change access board of device

Become Active Controller

Clear specified device

Send commands from string

Send commands asynchronously from

string

Enable/disable DMA

Change/disable EOS mode

Enable/disable END message

IBCMD (BD%,CMD$)

IBCMDA (BD%,CMD$)

IBDMA (BD%,V%)

IBEOS (BD%,V%)

IBEOT (BD%,V%)

Open device and return unit descriptor IBFIND (BDNAME$,BD%)

Go from Active Controller to standby IBGTS (BD%,V%)

Set/clear ist

Go to local

IBIST (BD%,V%)

IBLOC (BD%)

Place device online/offline

Change primary address

Pass control

IBONL (BD%,V%)

IBPAD (BD%,V%)

IBPCT (BD%)

Parallel poll configure

Read data to string

IBPPC (BD%,V%)

IBRD (BD%,RD$)

Read data asynchronously to string IBRDA (BD%,RD$)

Read data to file

IBRDF (BD%,FLNAME$)

Read data to integer array

IBRDI

(BD%,IARR%(0),CNT%)

IBRDIA

Read data asynch to integer array

(BD%,IARR%(0),CNT%)

IBRPP (BD%,PPR%)

IBRSC (BD%,V%)

IBRSP (BD%,SPR%)

IBRSV (BD%,V%)

IBSAD (BD%,V%)

IBSIC (BD%)

Conduct a parallel poll

Request/release system control

Return serial poll byte

Request service

Change secondary address

Send interface clear

Set/clear remote enable line

Abort asynchronous operation

Change/disable time limit

Configure applications monitor

Trigger selected device

IBSRE (BD%,V%)

IBSTOP (BD%)

IBTMO (BD%,V%)

IBTRAP (MASK%,V%)

IBTRG (BD%)

(continues)

©National Instruments Corp.

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GPIB-PC User Manual

BASICA/QuickBASIC GPIB-PC Function Calls

Section Four A

Table 4A.1 - BASICA GPIB-PC Functions (continued)

Description

Wait for selected event

Write data from string

CALL Function Syntax

IBWAIT (BD%,MASK%)

IBWRT (BD%,WRT$)

Write data asynchronously from string IBWRTA (BD%,WRT$)

Write data from file

IBWRTF (BD%,FLNAME$)

Write data from integer array

IBWRTI

(BD%,IARR%(0),CNT%)

Write data asynch from integer array IBWRTIA

(BD%,IARR%(0),CNT%)

The first argument of all function calls except IBFINDis the integer

variable BD%, which serves as a unit descriptor. Refer to the IBFIND

function description and Section Three for additional information on the

use of this unit descriptor.

Table 4A.2 contains a complete list of the QuickBASIC GPIB calls,

their parameters, and a short description of each.

Table 4A.2 - QuickBASIC GPIB-PC Calls

Description

CALL Function Syntax

IBBNA (BD%,BNAME$)

IBCAC (BD%,V%)

IBCLR (BD%)

Change access board of device

Become Active Controller

Clear specified device

Send commands from string

Send commands asynchronously from

string

Enable/disable DMA

Change/disable EOS mode

Enable/disable END message

IBCMD (BD%,CMD$)

IBCMDA (BD%,CMD$)

IBDMA (BD%,V%)

IBEOS (BD%,V%)

IBEOT (BD%,V%)

Open device and return unit descriptor IBFIND (BDNAME$,BD%)

Go from Active Controller to standby IBGTS (BD%,V%)

Set/clear ist

Go to local

IBIST (BD%,V%)

IBLOC (BD%)

Place device online/offline

Change primary address

IBONL (BD%,V%)

IBPAD (BD%,V%)

(continues)

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©National Instruments Corp.

Section Four A

BASICA/QuickBASIC GPIB-PC Function Calls

Table 4A.2 - QuickBASIC GPIB-PC Calls (cont.)

Description

Pass control

CALL Function Syntax

IBPCT (BD%)

Parallel poll configure

Read data to string

IBPPC (BD%,V%)

IBRD (BD%,RD$)

Read data asynchronously to string IBRDA (BD%,RD$)

Read data to file

Read data to integer array

IBRDF (BD%,FLNAME$)

IBRDI (BD%,VARPTR

(IARR%(0)),CNT%)

IBRDIA (BD%,VARPTR

(IARR%(0)),CNT%

IBRPP (BD%,PPR%)

IBRSC (BD%,V%)

IBRSP (BD%,SPR%)

IBRSV (BD%,V%)

IBSAD (BD%,V%)

IBSIC (BD%)

Read data asynch to integer array

Conduct a parallel poll

Request/release system control

Return serial poll byte

Request service

Change secondary address

Send interface clear

Set/clear remote enable line

Abort asynchronous operation

Change/disable time limit

Configure applications monitor

Trigger selected device

Wait for selected event

Write data from string

IBSRE (BD%,V%)

IBSTOP (BD%)

IBTMO (BD%,V%)

IBTRAP (MASK%,V%)

IBTRG (BD%)

IBWAIT (BD%,MASK%)

IBWRT (BD%,WRT$)

Write data asynchronously from string IBWRTA (BD%,WRT$)

Write data from file

Write data from integer array

IBWRTF (BD%,FLNAME$)

IBWRTI (BD%,VARPTR

(IARR%(0)),CNT%

Write data asynch from integer array IBWRTIA (BD%,VARPTR

(IARR%(0)),CNT%

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BASICA/QuickBASIC GPIB-PC Function Calls

Section Four A

Table 4A.3 - QuickBASIC GPIB-PC Calls

CALL Function Syntax

Description

Change access board of device

Become Active Controller

Clear specified device

Send commands from string

Send commands asynchronously from

string

Enable/disable DMA

Change/disable EOS mode

Enable/disable END message

IBBNA (BD%,BNAME$)

IBCAC (BD%,V%)

IBCLR (BD%)

IBCMD (BD%,CMD$)

IBCMDA (BD%,CMD$)

IBDMA (BD%,V%)

IBEOS (BD%,V%)

IBEOT (BD%,V%)

Open device and return unit descriptor IBFIND (BDNAME$,BD%)

Go from Active Controller to Standby IBGTS (BD%,V%)

Set/clear ist

Go to local

IBIST (BD%,V%)

IBLOC (BD%)

Place device online/offline

Change primary address

Pass control

IBONL (BD%,V%)

IBPAD (BD%,V%)

IBPCT (BD%)

Parallel poll configure

Read data to string

IBPPC (BD%,V%)

IBRD (BD%,RD$)

Read data asynchronously to string IBRDA (BD%,RD$)

Read data to file

IBRDF (BD%,FLNAME$)

Read data to integer array

IBRDI

(BD%,IARR%(),CNT%)

IBRDIA

Read data asynch to integer array

(BD%,IARR%(),CNT%

IBRPP (BD%,PPR%)

IBRSC (BD%,V%)

IBRSP (BD%,SPR%)

IBRSV (BD%,V%)

IBSAD (BD%,V%)

IBSIC (BD%)

Conduct a parallel poll

Request/release system control

Return serial poll byte

Request service

Change secondary address

Send interface clear

Set/clear remote enable line

Abort asynchronous operation

IBSRE (BD%,V%)

IBSTOP (BD%)

(continues)

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©National Instruments Corp.

Section Four A

BASICA/QuickBASIC GPIB-PC Function Calls

Table 4A.3 - QuickBASIC GPIB-PC Calls (continued)

Description

CALL Function Syntax

IBTMO (BD%,V%)

IBTRAP (MASK%,V%)

IBTRG (BD%)

IBWAIT (BD%,MASK%)

IBWRT (BD%,WRT$)

Change/disable time limit

Configure applications monitor

Trigger selected device

Wait for selected event

Write data from string

Write data asynchronously from string IBWRTA (BD%,WRT$)

Write data from file

IBWRTF (BD%,FLNAME$)

Write data from integer array

IBWRTI

(BD%,IARR%(),CNT%

Write data asynch from integer array IBWRTIA

(BD%,IARR%(),CNT%

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BASICA/QuickBASIC GPIB-PC Function Calls

Section Four A

New GPIB-PC Functions

Since QuickBASIC Version 4.0 now supports true functions, the

language interface has been expanded to include function versions of

the existing GPIB calls. Here are some important points to be aware of:

•

All existing subroutines are still available via the CALL

statement, and existing applications do not require any

changes.

The names of the new functions are identical to the existing

subroutines, except that the second letter of each name has

been changed from Bto L. For example, the subroutine IBSIC

is now also available as the function ILSIC.

•

GPIB subroutine and function calls may be freely mixed

throughout a program.

The include file QBDECL4.BAScontains a complete list of

both subroutine and function declarations, complete with

parameter list specifications to aid in type checking at compile

time. You must include this file in all application programs

using GPIB calls.

•

In general, the functions behave identically to the subroutines

with the few exceptions noted in the following paragraph. The

description of each subroutine found in the GPIB-PC User

Manual can be applied to the new functions, except for the

syntax-specific information.

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©National Instruments Corp.

Section Four A

BASICA/QuickBASIC GPIB-PC Function Calls

There are a few differences between the existing subroutines and the

new functions:

• ILFIND returns a descriptor associated with the specified device.

Use this value in all subsequent functions calls that access that

device. Normal usage would resemble the following:

BD% = ILFIND ("GPIB0")

• ILCMD, ILCMDA, ILRD, ILRDA, and ILWRTArequire a third

parameter which specifies the number of bytes to transfer. The

function syntax is as follows:

ILCMD (BD%, CMD$, CNT%)

ILCMDA (BD%, CMD$, CNT%)

ILRD (BD%, RD$, CNT%)

ILRDA (BD%, RD$, CNT%)

ILWRT (BD%, WRT$, CNT%)

ILWRTA (BD%, WRT$, CNT%)

•

All functions except ILFINDreturn the value of IBSTA. This

permits the following construct:

IF IBRD (BD%, RD%, CNT%) < 0 THEN CALL

GPIBERROR

Table 4A.4 contains a complete list of the new QuickBASIC GPIB

functions, their parameters, and a short description of each.

©National Instruments Corp.

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GPIB-PC User Manual

BASICA/QuickBASIC GPIB-PC Function Calls

Section Four A

Table 4A.4 - QuickBASIC Version 4.0 GPIB-PC Functions

Description

Function Syntax

Change access board of device

Become Active Controller

Clear specified device

ILBNA (BD%,BNAME$)

ILCAC (BD%,V%)

ILCLR (BD%)

Send commands from string

Send commands asynchronously from

string

ILCMD (BD%,CMD$,CNT%)

ILCMDA (BD%,CMD$,CNT%)

ILDMA (BD%,V%)

Enable/disable DMA

Change/disable EOS mode

Enable/disable END message

ILEOS (BD%,V%)

ILEOT (BD%,V%)

Open device and return unit descriptor ILFIND (BDNAME$,BD%)

Go from Active Controller to standby ILGTS (BD%,V%)

Set/clear ist

Go to local

ILIST (BD%,V%)

ILLOC (BD%)

Place device online/offline

Change primary address

Pass control

ILONL (BD%,V%)

ILPAD (BD%,V%)

ILPCT (BD%)

Parallel poll configure

Read data to string

ILPPC (BD%,V%)

ILRD (BD%,RD$,CNT%)

Read data asynchronously to string ILRDA (BD%,RD$,CNT%)

Read data to file

ILRDF (BD%,FLNAME$)

Read data to integer array

ILRDI

(BD%,IARR%(),CNT%)

ILRDIA

Read data asynch to integer array

(BD%,IARR%(),CNT%)

ILRPP (BD%,PPR%)

ILRSC (BD%,V%)

ILRSP (BD%,SPR%)

ILRSV (BD%,V%)

ILSAD (BD%,V%)

ILSIC (BD%)

Conduct a parallel poll

Request/release system control

Return serial poll byte

Request service

Change secondary address

Send interface clear

Set/clear remote enable line

Abort asynchronous operation

Change/disable time limit

Trigger selected device

ILSRE (BD%,V%)

ILSTOP (BD%)

ILTMO (BD%,V%)

ILTRG (BD%)

(continues)

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©National Instruments Corp.

Section Four A

BASICA/QuickBASIC GPIB-PC Function Calls

Table 4A.4 - QuickBASIC Version 4.0 GPIB-PC Functions

(continued)

Description

Function Syntax

Configure applications monitor

Wait for selected event

Write data from string

ILTRAP (MASK%,V%)

ILWAIT (BD%,MASK%)

ILWRT (BD%,WRT$,CNT%)

Write data asynchronously from string ILWRTA (BD%,WRT$,CNT%)

Write data from file

ILWRTF (BD%,FLNAME$)

Write data from integer array

ILWRTI

(BD%,IARR%(),CNT%)

Write data asynch from integer array ILWRTIA

(BD%,IARR%(),CNT%)

GPIB-PC Function Descriptions

The remainder of this section provides a detailed description of each

GPIB-PC function.

©National Instruments Corp.

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BASICA/QuickBASIC GPIB-PC Function Calls

Section Four A

BASICA/QuickBASIC

IBBNA

BASICA/QuickBASIC

IBBNA

Purpose:

Format:

Change access board of device

CALL IBBNA (BD%,BNAME$)

Remarks: BD% specifies a device. BNAME$ specifies the new access

board to be used in all device calls to that device. IBBNA

is needed only to alter the board assignment from its

configuration setting.

The IBBNAfunction identifies the board that will be used

in subsequent device functions to access the specified

device. IBBNA permits you to alter the association of

devices and interface boards from the settings originally

configured with the configuration program.

The assignment made by this function remains in effect

until IBBNAis called again, the IBONLor IBFIND

function is called, or the system is rebooted. The original

configuration established with the configuration program is

not permanently changed.

Refer also to Table 2.1.

Device Example:

1. Associate the device DVM%with the interface board "GPIB0".

100 REM DVM is a name assigned using

110 REM IBCONF.

120 REM (GPIB0 is a factory default board

130 REM name which cannot be changed).

140 BDNAME$ = "DVM"

150 CALL IBFIND (BDNAME$,DVM%)

160 REM This call to IBBNA establishes

170 REM GPIB0 as the access board for the

180 REM device DVM%.

190 BNAME$ = "GPIB0"

200 CALL IBBNA (DVM%,BNAME$)

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©National Instruments Corp.

Section Four A

BASICA/QuickBASIC GPIB-PC Function Calls

BASICA/QuickBASIC

IBCAC

BASICA/QuickBASIC

IBCAC

Purpose:

Format:

Become Active Controller

CALL IBCAC (BD%,V%)

Remarks: BD%specifies an interface board. If V%is non-zero, the

GPIB-PC takes control synchronously with respect to data

transfer operations; otherwise, the GPIB-PC takes control

immediately (and possibly asynchronously).

To take control synchronously, the GPIB-PC asserts the

ATN signal in such a way as to ensure that data being

transferred on the GPIB is not corrupted. If a data

handshake is in progress, the take control action is

postponed until the handshake is complete; if a handshake

is not in progress, the take control action is done

immediately. Synchronous take control is not guaranteed if

an IBRDor IBWRToperation completed with a timeout or

error.

Asynchronous take control should be used in situations

where it appears to be impossible to gain control

synchronously (e.g., after a timeout error).

It is generally not necessary to use the IBCAC function in

most applications. Functions such as IBCMDand IBRPP,

which require that the GPIB-PC take control, do so

automatically.

The ECIC error results if the GPIB-PC is not CIC.

Board Examples:

1. Take control immediately without regard to any data handshake

in progress.

100 V% = 0

110 CALL IBCAC (BRD0%,V%)

120 REM IBSTA% should show that the

130 REM interface board is now CAC, i.e.,

140 REM CIC with ATN asserted.

©National Instruments Corp.

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BASICA/QuickBASIC GPIB-PC Function Calls

Section Four A

2. Take control synchronously and assert ATN following a read

operation.

100 CALL IBRD (BRD0%,RD$)

110 V% = 1

120 CALL IBCAC (BRD0%,V%)

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Section Four A

BASICA/QuickBASIC GPIB-PC Function Calls

BASICA/QuickBASIC

IBCLR

BASICA/QuickBASIC

IBCLR

Purpose:

Format:

Clear specified device

CALL IBCLR (BD%)

Remarks: BD% specifies a device.

The IBCLR function clears the internal or device functions

of a specified device. On exit, all devices are unaddressed.

IBCLRcalls the board IBCMDfunction to send the

following commands using the designated access board:

•

Listen address of the device;

Secondary address of the device, if applicable;

Selected Device Clear (SDC); and

Untalk (UNT) and Unlisten (UNL)

Other command bytes may be sent as necessary.

Refer to IBCMDfor additional information. Refer also to

the discussion of device functions and the discussion

clearing the device and clearing the GPIB in Section

Three.

Device Example:

1. Clear the device VMTR%.

100 CALL IBCLR (VMTR%)

©National Instruments Corp.

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BASICA/QuickBASIC GPIB-PC Function Calls

Section Four A

BASICA/QuickBASIC

IBCMD

BASICA/QuickBASIC

IBCMD

Purpose:

Format:

Send commands from string

CALL IBCMD (BD%,CMD$)

Remarks: BD%specifies an interface board. CMD$ contains the

commands to be sent over the GPIB.

The IBCMD function is used to transmit interface messages

(commands) over the GPIB. These commands, which are

listed in Appendix A, include device talk and listen

addresses, secondary addresses, serial and parallel poll

configuration messages, and device clear and trigger

instructions. The IBCMDfunction is also used to pass GPIB

control to another device. This function is NOT used to

transmit programming instructions to devices.

Programming instructions and other device-dependent

information are transmitted with the read and write

functions.

The IBCMDoperation terminates on any of the following

events:

•

All commands are successfully transferred;

Error is detected;

Time limit is exceeded;

Take Control (TCT) command is sent; or

Interface Clear (IFC) message is received from the

System Controller (not the GPIB-PC).

After termination, the IBCNT% variable contains the

number of commands sent. A short count can occur on any

event but the first.

An ECIC error results if the GPIB-PC is not CIC. If it is not

Active Controller, it takes control and asserts ATN prior to

sending the command bytes. It remains Active Controller

afterward.

GPIB-PC User Manual

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©National Instruments Corp.

Section Four A

BASICA/QuickBASIC GPIB-PC Function Calls

In the examples that follow, GPIB commands and

addresses are coded as printable ASCII characters. When

the values to be sent over the GPIB correspond to printable

ASCII characters, this is the simplest means of specifying

the values. Refer to Appendix A for conversions of numeric

values to ASCII characters.

Board Examples:

1. Unaddress all Listeners with the Unlisten (UNL or ASCII ?)

command and address a Talker at &H46 (ASCII F) and a

Listener at &H31 (ASCII 1).

100 CMD$ = "?F1"

' UNL TAD1 LAD2

110 CALL IBCMD (BRD0%,CMD$)

2. Same as Example 1, except the Listener has a secondary

address of &H6E (ASCII n).

100 CMD$ = "?F1n" ' UNL TAD1 LAD2 SAD2

110 CALL IBCMD (BRD0%,CMD$)

3. Clear all GPIB devices (i.e., reset internal functions) with the

Device Clear (DCL or &H14) command.

100 CMD$ = CHR$ (&H14) ' DCL

110 CALL IBCMD (BRD0%,CMD$)

4. Clear two devices with listen addresses of &H21 (ASCII !) and

&H28 (ASCII ( (left parenthesis)) with the Selected Device

Clear (SDC or &H04) command.

100 CMD$ = "!(" + CHR$(&H04) ' LAD1 LAD2 SDC

110 CALL IBCMD (BRD0%,CMD$)

5. Trigger any devices previously addressed to listen with the

Group Execute Trigger (GET or &H08) command.

100 CMD$ = CHR$(&H08) ' GET

110 CALL IBCMD (BRD0%,CMD$)

©National Instruments Corp.

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BASICA/QuickBASIC GPIB-PC Function Calls

Section Four A

6. Unaddress all Listeners and serially poll a device at talk

address &H52 (ASCII R) using the Serial Poll Enable (SPE or

&H18) and Serial Poll Disable (SPD or &H19) commands (the

GPIB-PC listen address is &H20 or ASCII space).

100 CMD$ ="?R " + CHR$(&H18)'UNL TAD MLA SPE

110 CALL IBCMD (BRD0%,CMD$)

120 RD$ = SPACE$(1) ' Declare RD buffer.

130 CALL IBRD (BRD0%,RD$)

140 REM After checking the status byte in

150 REM RD$, disable this device and

160 REM unaddress it with the Untalk.

160 REM (UNT or ASCII _) command before

170 REM polling the next one.

180 CMD$ = CHR$(&H19) + "_" ' SPD UNT

190 CALL IBCMD (BRD0%,CMD$)

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©National Instruments Corp.

Section Four A

BASICA/QuickBASIC GPIB-PC Function Calls

BASICA/QuickBASIC

IBCMDA

BASICA/QuickBASIC

IBCMDA

Purpose:

Format:

Send commands asynchronously from string

CALL IBCMDA (BD%,CMD$)

Remarks: BD%specifies an interface board. CMD$ contains the

commands to be sent over the GPIB.

The IBCMDAfunction is used to transmit interface

messages (commands) over the GPIB. These commands,

which are listed in Appendix A, include device talk and

listen addresses, secondary addresses, serial and parallel

poll configuration messages, and device clear and trigger

instructions. The IBCMDAfunction is also used to pass

GPIB control to another device. This function is NOT used

to transmit programming instructions to devices.

Programming instructions and other device-dependent

information are transmitted with the write and read

functions.

IBCMDAis used in place of IBCMD when the application

program must perform other functions while processing the

GPIB I/O operation. IBCMDAreturns after starting the I/O

operation. If the number of bytes to send is small and the

bytes are accepted quickly by the GPIB device(s), the

operation may complete on the initial call. In this case,

the CMPL bit will be set in IBSTA%. If the operation does

not complete on the initial call, you should monitor the

IBSTA%variable after subsequent calls (usually IBWAIT

calls) to know that the I/O is completed. When CMPL

becomes set in IBSTA%, indicating that the I/O is

complete, the number of bytes sent is reported in the

IBCNT%variable.

Between the issuing of the IBCMDAcall and the

corresponding CMPL, other GPIB function calls to this

board will return the error EOIP, with the following

exceptions:

• IBSTOP

to cancel the asynchronous I/O;

• IBWAIT

to monitor other GPIB conditions; and

©National Instruments Corp.

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GPIB-PC User Manual

BASICA/QuickBASIC GPIB-PC Function Calls

Section Four A

• IBONL

to cancel the I/O and reset the interface.

The asynchronous I/O started by IBCMDAterminates for the

same reasons IBCMD terminates.

An ECIC error results if the GPIB-PC is not CIC. If it is not

Active Controller, the GPIB-PC takes control and asserts

ATN prior to sending the command bytes. It remains

Active Controller afterward. The ENOL error does NOT

occur if there are no Listeners.

Board Example:

1. Address several devices for a broadcast message to follow

while testing for a high priority event to occur.

100 REM The interface board BRD0% at talk

110 REM address &H40 (ASCII @), addresses

120 REM nine Listeners at addresses &H31-

130 REM &H39 (ASCII 1-9) to receive the

140 REM broadcast message.

150 CMD$ = "?@123456789" ' UNL MTA

160

' LAD1...LAD9

170 CALL IBCMDA (BRD0%,CMD$)

180 MASK% = $4100

190

200 CALL EVENTTST

210

220

230

' Wait for timeout or

' I/O completion.

' Unspecified routine

' to test and process

' a high priority

' event.

240 CALL IBWAIT (BRD0%,MASK%)

250 REM Loop until complete while no error

260 REM has occurred.

270 IF (IBSTA% AND &H100) = 0 GOTO 180

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©National Instruments Corp.

Section Four A

BASICA/QuickBASIC GPIB-PC Function Calls

BASICA/QuickBASIC

IBDMA

BASICA/QuickBASIC

IBDMA

Purpose:

Format:

Enable or disable DMA

CALL IBDMA (BD%,V%)

Remarks: BD%specifies an interface board. If V%is non-zero, DMA

transfers between the GPIB-PC and memory are used for

read and write operations. If V%is zero, programmed I/O is

used in place of DMA I/O.

If you enabled DMA at configuration time, assigning DMA

channel 1, 2, or 3, this function can be used to switch

between programmed I/O and DMA using the selected

channel. If you disabled DMA at configuration time,

calling this function with V% equal to a non-zero value

results in an ECAP error.

The assignment made by this function remains in effect

until IBDMAis called again, the IBONLor IBFIND

function is called, or the system is rebooted.

When IBDMA is called and an error does not occur, the

previous value of V%is stored in IBERR%.

On machines without DMA capability, calling this function

with V%= 0 has no effect, and calling it with a non-zero V%

results in an ECAP error.

Refer also to Table 2.1.

Board Examples:

1. Enable DMA transfers using the previously configured channel.

100 V% = 1 ' Any non-zero value will do.

110 CALL IBDMA (BRD0%,V%)

2. Disable DMAs and use programmed I/O exclusively.

100 V% = 0

110 CALL IBDMA (BRD0%,V%)

©National Instruments Corp.

4A-25

GPIB-PC User Manual

BASICA/QuickBASIC GPIB-PC Function Calls

Section Four A

BASICA/QuickBASIC

IBEOS

BASICA/QuickBASIC

IBEOS

Purpose:

Format:

Change or disable end-of-string termination mode

CALL IBEOS (BD%,V%)

Remarks: BD% specifies a device or an interface board. V% specifies

the EOS character and the data transfer termination method

according to Table 4A.5. IBEOSis needed only to alter the

value from its configuration setting.

The assignment made by this function remains in effect

until IBEOSis called again, the IBONLor IBFIND

function is called, or the system is rebooted.

When IBEOS is called and an error does not occur, the

previous value of V%is stored in IBERR%.

Table 4A.5 - Data Transfer Termination Method

Method

Value of V%

High Byte Low Byte

A. Terminate read when EOS

is detected

B. Set EOI with EOS on write

function

C. Compare all 8 bits of EOS

byte rather than low 7 bits

(all read and write functions)

00000100

00001000

00010000

EOS

Methods A and C determine how read operations terminate.

If Method A alone is chosen, reads terminate when the low

7 bits of the byte that is read match the low 7 bits of the

EOS character. If Methods A and C are chosen, a full 8-bit

comparison is used.

GPIB-PC User Manual

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©National Instruments Corp.

Section Four A

BASICA/QuickBASIC GPIB-PC Function Calls

Methods B and C together determine when write operations

send the END message. If Method B alone is chosen, the

END message is sent automatically with the EOS byte

when the low 7 bits of that byte match the low 7 bits of the

EOS character. If Methods B and C are chosen, a full 8-bit

comparison is used.

Note that defining an EOS byte for a device or board does

not cause the handler to automatically send that byte when

performing IBWRTs. To send the EOS byte, your

application program must include it in the data string it

defines.

Device IBEOS Function:

When BD% specifies a device, the options coded in V% are used for all

device reads and writes in which that device is specified.

Board IBEOS Function:

When BD% specifies a board, the options coded in V% become

associated with all board reads and writes.

Refer also to IBEOTand Table 2.1.

Device Example:

1. Send END when the linefeed character is written to the device

DVM%.

10 EOSV% = &H0A

' EOS info for IBEOS.

100 V% = EOSV% + &H0800

110 CALL IBEOS (DVM%,V%)

120 WRT$ = "123" + CHR$(&H0A)

130

140

150

160

' Data bytes to be

' written. EOS

' character is the

' last byte.

170 CALL IBWRT (DVM%,WRT$)

©National Instruments Corp.

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GPIB-PC User Manual

BASICA/QuickBASIC GPIB-PC Function Calls

Section Four A

Board Examples:

1. Program the interface board BRD0%to terminate a read on

detection of the linefeed character (&H0A) that is expected to

be received within 200 bytes.

10 EOSV% = &H0A

100 V% = EOSV% + &H0400

110 CALL IBEOS (BRD0%,V%)

120 REM Assume board has been addressed; do

130 REM board read.

140 RD$ = SPACE$(200)

150 CALL IBRD (BRD0%,RD$)

160 REM The END bit in IBSTA% is set if the

170 REM read terminated on the EOS

180 REM character. The value of IBCNT%

190 REM shows the number of bytes received.

2. To program the interface board BRD0%to terminate read

operations on the 8-bit value &H82 rather than the 7-bit

character &H0A, change lines 10 and 100 in Example 1.

10 EOSV% = &H82

100 V% = EOSV% + &H1400

3. To disable read termination on receiving the EOS character for

operations involving the interface board BRD0%, change line

100 in Example 1.

100 V% = EOSV%

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©National Instruments Corp.

Section Four A

BASICA/QuickBASIC GPIB-PC Function Calls

4. Send END when the linefeed character is written for operations

involving the interface board BRD0%.

10 EOSV% = &H0A ' EOS info for IBEOS.

100 V% = EOSV% + &H0800

110 CALL IBEOS (BRD0%,V%)

120 REM Assume the board has been

130 REM addressed; do board write.

140 WRT$ = "123" + CHR$(&H0A)

150 CALL IBWRT (BRD0%,WRT$)

5. To send END with linefeeds and to terminate reads on linefeeds

for operations involving the interface board BRD0%, change line

100 in Example 4.

100 V% = EOSV% + &H0C00

©National Instruments Corp.

4A-29

GPIB-PC User Manual

BASICA/QuickBASIC GPIB-PC Function Calls

Section Four A

BASICA/QuickBASIC

IBEOT

BASICA/QuickBASIC

IBEOT

Purpose:

Format:

Enable or disable END termination message on write

operations

CALL IBEOT (BD%,V%)

Remarks: BD%specifies a device or an interface board. If V%is non-

zero, the END message is sent automatically with the last

byte of each write operation. If V%is zero, END is not sent.

IBEOTis needed only to alter the value from the

configuration setting.

The END message is sent when the GPIB EOI signal is

asserted during a data transfer and it is used to identify the

last byte of a data string without having to use an end-of-

string character. IBEOTis used primarily to send variable

length binary data.

The assignment made by this function remains in effect

until IBEOTis called again, the IBONLor IBFIND

function is called, or the system is rebooted.

When IBEOT is called and an error does not occur, the

previous value of V%is stored in IBERR%.

Device IBEOT Function:

When BD% specifies a device, the END termination message method

that is selected is used on all device I/O write operations to that device.

Board IBEOT Function:

When BD% specifies an interface board, the method that is selected is

used on all board-level I/O write operations, regardless of what device is

written to.

Refer also to IBEOSand to Table 2.1.

GPIB-PC User Manual

4A-30

©National Instruments Corp.

Section Four A

BASICA/QuickBASIC GPIB-PC Function Calls

Device Example:

1. Send the END message with the last byte of all subsequent

writes to the device PLOTTER%.

100 V% = 1 ' Enable sending of EOI.

110 CALL IBEOT (PLOTTER%,V%)

120 REM It is assumed that WRT$ contains

130 REM the data to be written to the GPIB.

140 CALL IBWRT (PLOTTER%,WRT$)

Board Examples:

1. Stop sending END with the last byte for calls directed to the

interface board BRD0%.

100 V% = 0 ' Disable sending of EOI.

110 CALL IBEOT (BRD0%,V%)

2. Send the END message with the last byte of all subsequent

write operations directed to the interface board BRD0%.

100 V% = 1

' Enable sending of EOI.

110 CALL IBEOT (BRD0%,V%)

120 REM It is assumed that WRT$ contains

130 REM the data to be written and all

140 REM Listeners have been addressed.

150 CALL IBWRT (BRD0%,WRT$)

©National Instruments Corp.

4A-31

GPIB-PC User Manual

BASICA/QuickBASIC GPIB-PC Function Calls

Section Four A

BASICA/QuickBASIC

IBFIND

BASICA/QuickBASIC

IBFIND

Purpose:

Format:

Open device and return the unit descriptor associated with

the given name

CALL IBFIND (BDNAME$,BD%)

Remarks: BDNAME$is a string containing a default or configured

device or board name. BD% is a variable containing the

unit descriptor returned by IBFIND.

IBFINDreturns a number that is used in each function to

identify the particular device or board that is used or is the

object of that function. Calling IBFINDis required to

associate a variable name in the application program with

a particular default or configured device or board name.

The name used in the BDNAME$ argument must match

exactly the default or configured device or board name.

The number returned, referred throughout this manual as a

unit descriptor, is assigned here to the variable BD%, which

is used in all references to that device or board in GPIB

function calls.

IBFINDperforms the equivalent of IBONLto open the

specified device or board and to initialize software

parameters to their default configuration settings. The

variable name selected should suggest the actual name of

the device or board in order to simplify programming effort.

If the IBFIND call fails, a negative number is returned in

place of the unit descriptor. The most probable reason for a

failure is that the string argument passed into IBFINDdoes

not match the default or configured device or board name.

GPIB-PC User Manual

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©National Instruments Corp.

Section Four A

BASICA/QuickBASIC GPIB-PC Function Calls

Device Example:

1. Assign the unit descriptor associated with the device named

"FSDVM" (Fluke Sampling Digital Voltmeter) to the variable

FSDVM%.

100 BDNAME$ = "FSDVM" ' Device name

110

120

' assigned at

' configuration time

130 CALL IBFIND (BDNAME$,FSDVM%)

140 IF FSDVM% < 0 GOTO 1000 ' ERROR ROUTINE

Board Example:

1. Assign the unit descriptor associated with the interface board

"GPIB0"to the variable BRD0%.

100 BDNAME$ = "GPIB0" ' Board name

110

120

' assigned at

' configuration time

130 CALL IBFIND (BDNAME$,BRD0%)

140 IF BRD0% < 0 GOTO 1000 ' ERROR ROUTINE

©National Instruments Corp.

4A-33

GPIB-PC User Manual

BASICA/QuickBASIC GPIB-PC Function Calls

Section Four A

BASICA/QuickBASIC

IBGTS

BASICA/QuickBASIC

IBGTS

Purpose:

Format:

Go from Active Controller to Standby

CALL IBGTS (BD%,V%)

Remarks: BD%specifies an interface board. If V%is non- zero, the

GPIB-PC shadow handshakes the data transfer as an

Acceptor, and when the END message is detected, the

GPIB-PC enters a Not Ready For Data (NRFD) handshake

holdoff state on the GPIB. If V%is zero, no shadow

handshake or holdoff is done.

The IBGTSfunction causes the GPIB-PC to go to the

Controller Standby state and to unassert the ATN signal if

it initially is the Active Controller. IBGTS permits GPIB

devices to transfer data without the GPIB-PC being a party

to the transfer.

If the shadow handshake option is activated, the GPIB-PC

participates in data handshake as an Acceptor without

actually reading the data. It monitors the transfers for the

END (EOI or end-of-string character) message and holds off

subsequent transfers. This mechanism allows the GPIB-PC

to take control synchronously on a subsequent operation

such as IBCMDor IBRPP.

Before performing an IBGTSwith shadow-handshake, the

IBEOSfunction should be called to establish the proper

end-of-string character or to disable EOS detection if the

end-of-string character in use by the talker is not known.

The ECIC error results if the GPIB-PC is not CIC.

Refer also to IBCAC.

In the example that follows, GPIB commands and

addresses are coded as printable ASCII characters. When

the hex values to be sent over the GPIB correspond to

printable ASCII characters, this is the simplest means of

specifying the values. Refer to Appendix A for conversions

of hex values to ASCII characters.

GPIB-PC User Manual

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©National Instruments Corp.

Section Four A

BASICA/QuickBASIC GPIB-PC Function Calls

Board Example:

1. Turn the ATN line off with the IBGTS function after

unaddressing all Listeners with the Unlisten (UNL or ASCII ?)

command, addressing a Talker at &H46 (ASCII F) and

addressing a Listener at &H31 (ASCII 1) to allow the Talker to

send data messages.

100 CMD$ = "?F1" ' UNL MTA1 MLA2

110 CALL IBCMD (BRD0%,CMD$)

120 V% = 1

' Listen in continuous mode.

130 CALL IBGTS (BRD0%,V%)

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BASICA/QuickBASIC GPIB-PC Function Calls

Section Four A

BASICA/QuickBASIC

IBIST

BASICA/QuickBASIC

IBIST

Purpose:

Format:

Set or clear individual status bit for Parallel Polls

CALL IBIST (BD%,V%)

Remarks: BD%specifies an interface board. If V%is non-zero, the

individual status bit is set. If V% is zero, the bit is cleared.

The IBISTfunction is used when the GPIB-PC

participates in a parallel poll that is conducted by another

device that is the Active Controller. The Active Controller

conducts a parallel poll by asserting the EOI signal to send

the Identify (IDY) message. While this message is active,

each device which has been configured to participate in the

poll responds by asserting a predetermined GPIB data line

either true or false, depending on the value of its local ist

bit. The GPIB-PC, for example, can be assigned to drive

the DIO3 data line true if ist=1 and false if ist=0;

conversely, it can be assigned to drive DIO3 true if ist=0

and false if ist=1.

The relationship between the value of ist, the line that is

driven, and the sense at which the line is driven is

determined by the Parallel Poll Enable (PPE) message in

effect for each device. The GPIB-PC is capable of

receiving this message either locally, via the IBPPC

function, or remotely, via a command from the Active

Controller. Once the PPE message is executed, the IBIST

function changes the sense at which the line is driven

during the parallel poll, and in this fashion the GPIB-PC

can convey a one-bit, device dependent message to the

Controller.

When IBIST is called and an error does not occur, the

previous value of ist is stored in IBERR%.

Refer also to IBPPCand Table 2.1.

GPIB-PC User Manual

4A-36

©National Instruments Corp.

Section Four A

BASICA/QuickBASIC GPIB-PC Function Calls

Board Examples:

1. Set the individual status bit.

100 V% = 1 ' Any non-zero value will do.

110 CALL IBIST (BRD0%,V%)

2. Clear the individual status bit.

100 V% = 0

110 CALL IBIST (BRD0%,V%)

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BASICA/QuickBASIC GPIB-PC Function Calls

Section Four A

BASICA/QuickBASIC

IBLOC

BASICA/QuickBASIC

IBLOC

Purpose:

Format:

Go to Local

CALL IBLOC (BD%)

Remarks: BD% specifies a device or an interface board.

Unless the Remote Enable line has been unasserted with

the IBSRE function, all device functions automatically

place the specified device in remote program mode.

IBLOCis used to move devices temporarily from a remote

program mode to a local mode until the next device

function is executed on that device.

Device IBLOC Function:

IBLOC places the device indicated in local mode by calling IBCMDto

send the command sequence:

•

Unlisten (UNL);

Listen address of the device;

Secondary address of the device, if necessary;

Go To Local (GTL); and

Untalk (UNT) and Unlisten (UNL).

Other command bytes may be sent as necessary.

On exit, all devices are unaddressed.

Board IBLOC Function:

When BD% specifies an interface board, the board is placed in a local

state by sending the local Return To Local (rtl) message, provided it is

not locked in remote mode. The LOK bit of the status word indicates

whether the board is in a lockout state. The IBLOCfunction is used to

simulate a front panel Return To Local switch when the computer is

used as an instrument.

GPIB-PC User Manual

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©National Instruments Corp.

Section Four A

BASICA/QuickBASIC GPIB-PC Function Calls

Device Example:

1. Return the device DVM% to local state.

100 CALL IBLOC (DVM%)

Board Example:

1. Return the interface board BRD0%to local state.

100 CALL IBLOC (BRD0%)

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BASICA/QuickBASIC GPIB-PC Function Calls

Section Four A

BASICA/QuickBASIC

IBONL

BASICA/QuickBASIC

IBONL

Purpose:

Format:

Place the device or interface board online or offline

CALL IBONL (BD%,V%)

Remarks: BD%specifies a device or an interface board. If V%is non-

zero, the device or interface board is enabled for operation

(i.e., online). If V% is zero, it is held in a reset, disabled

mode (offline).

Taking a device or interface board offline may be thought

of as disconnecting its GPIB cable from the other devices.

IBONLcan also be used to restore the default configuration

settings of a device or interface board. Calling IBONLwith

V% non-zero when the device or interface board is already

online simply has the effect of restoring all configuration

settings to their defaults.

Device Examples:

1. Disable the device PLOTTER%.

100 V% = 0

110 CALL IBONL (PLOTTER%,V%)

2. Enable the device PLOTTER%after taking it offline temporarily.

100 BDNAME$ = "PLOTTER" ' Device name

110

120 CALL IBFIND (BDNAME$,PLOTTER%)

130 REM IBONL with V% non-zero is

'assigned at configuration time.

140 REM automatically performed as part of

150 REM IBFIND.

3. Reset the configuration settings of the device PLOTTER%to

their defaults.

100 V% = 1

110 CALL IBONL (PLOTTER%,V%)

GPIB-PC User Manual

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©National Instruments Corp.

Section Four A

BASICA/QuickBASIC GPIB-PC Function Calls

Board Examples:

1. Disable the interface board BRD0%.

100 V% = 0

110 CALL IBONL (BRD0%,V%)

2. Enable the interface board BRD0%after taking it offline

temporarily.

100 BDNAME$ = "GPIB0" 'Board name assigned

110

'at configuration time

120 CALL IBFIND (BDNAME$,BRD0%)

130 REM IBONL with V% non-zero is

140 REM automatically performed as part of

150 REM IBFIND.

3. Reset the configuration settings of the interface board BRD0%to

their defaults.

100 V% = 1

110 CALL IBONL (BRD0%,V%)

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BASICA/QuickBASIC GPIB-PC Function Calls

Section Four A

BASICA/QuickBASIC

IBPAD

BASICA/QuickBASIC

IBPAD

Purpose:

Format:

Change Primary Address

CALL IBPAD (BD%,V%)

Remarks: BD% specifies a device or an interface board. V% specifies

the primary GPIB address of the device or interface board.

IBPADis needed only to alter the value from its

configuration setting.

Only the low five bits of V% are significant and they must

not all be ones. Thus there are 31 valid GPIB addresses,

ranging from 0 to &H1E. An EARG error results if the

value of V%is not in this range.

The assignment made by this function remains in effect

until IBPADis called again, the IBONLor IBFIND

function is called, or the system is rebooted.

When IBPAD is called and an error does not occur, the

previous value of ist is stored in IBERR%. The previous

primary address is returned in IBERR%.

Device IBPAD Function:

When BD% specifies a device, IBPAD determines the talk and listen

addresses based on the value of V%for use in all I/O directed to that

device. A device listen address is formed by adding &H20 to the

primary address; the talk address is formed by adding &H40 to the

primary address. Consequently, a primary address of &H10 corresponds

to a Listen address of &H30 and a talk address of &H50. The actual

GPIB address of any device is set within that device, either with

hardware switches or a software program. Refer to the device

documentation for instructions.

Board IBPAD Function:

When BD%specifies a board, IBPADprograms the interface board to

respond to the primary talk and listen address indicated by V%.

Refer also to IBSAD, IBONL, and Table 2.1.

GPIB-PC User Manual

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©National Instruments Corp.

Section Four A

BASICA/QuickBASIC GPIB-PC Function Calls

Device Example:

1. Change the primary GPIB listen and talk address of the device

PLOTTER%from the configuration setting to &H2A and &H4A

respectively.

100 V% = &HA ' Lower 5 bits of GPIB address.

110 CALL IBPAD (PLOTTER%,V%)

Board Example:

1. Change the primary GPIB listen and talk address of the

interface board BRD0%from the configuration setting to &H27

and &H47 respectively.

100 V% = &H7 ' Lower 5 bits of GPIB address.

110 CALL IBPAD (BRD0%,V%)

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BASICA/QuickBASIC GPIB-PC Function Calls

Section Four A

BASICA/QuickBASIC

IBPCT

BASICA/QuickBASIC

IBPCT

Purpose:

Format:

Pass Control

CALL IBPCT (BD%)

Remarks: BD% specifies a device.

The IBPCTfunction passes CIC authority to the specified

device from the access board assigned to that device. The

board automatically goes to Controller Idle State (CIDS).

The function assumes that the device has Controller

capability.

IBPCTcalls the board IBCMDfunction to send the

following commands:

•

Talk address of the device;

Secondary address of the device, if applicable; and

Take Control (TCT).

Other command bytes may be sent as necessary.

Refer to IBCMDfor additional information.

Device Example:

1. Pass control to the device IBMXT%.

100 CALL IBPCT (IBMXT%)

GPIB-PC User Manual

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©National Instruments Corp.

Section Four A

BASICA/QuickBASIC GPIB-PC Function Calls

BASICA/QuickBASIC

IBPPC

BASICA/QuickBASIC

IBPPC

Purpose:

Format:

Parallel Poll Configure

CALL IBPPC (BD%,V%)

Remarks: BD% specifies a device or an interface board. V%must be a

valid parallel poll enable/disable command, or zero.

When IBPPC is called and an error does not occur, the

previous value of ist is stored in IBERR%.

Device IBPPC Function:

When BD% specifies a device, the IBPPC function enables or disables

the device from responding to parallel polls.

IBPPCcalls the board IBCMDfunction to send the following

commands:

•

Listen address of the device;

Secondary address of the device, if applicable;

Parallel Poll Configure (PPC); and

Parallel Poll Enable (PPE) or Disable (PPD)

Other command bytes are sent if necessary.

Each of the 16 PPE messages specifies the GPIB data line (DIO1

through DIO8) and sense (one or zero) that the device must use when

responding to the Identify (IDY) message during a parallel poll. The

assigned message is interpreted by the device along with the current

value of the individual status (ist) bit to determine if the selected line is

driven true or false. For example, if the PPE=&H64, DIO5 is driven true

if ist=0 and false if ist=1. And if PPE=&H68, DIO1 is driven true if

ist=1 and false if ist=0. Any PPD message or zero value cancels the

PPE message in effect.

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BASICA/QuickBASIC GPIB-PC Function Calls

Section Four A

Which PPE and PPD messages are sent and the meaning of a particular

parallel poll response are all system dependent protocol matters to be

determined by you.

On exit, all devices are unaddressed.

Board IBPPC Function:

When BD% specifies an interface board, the board itself is programmed

to respond to a parallel poll by setting its local poll enable (lpe)

message to the value of V%.

Refer also to IBCMD, IBIST, and Table 2.1 for additional information.

Device Examples:

1. Configure the device DVM%to respond to a parallel poll by

sending data line DIO5 true (ist=0).

100 V% = &H64

110 CALL IBPPC (DVM%,V%)

2. Configure the device DVM%to respond to a parallel poll by

sending data line DIO1 true (ist=1).

100 V% = &H68

110 CALL IBPPC (DVM%,V%)

3. Cancel the parallel poll configuration of the device DVM%.

100 V% = &H70

110 CALL IBPPC (DVM%,V%)

Board Example:

1. Configure the interface board BRD0%to respond to a parallel

poll by sending data line DIO5 true (ist=0).

100 V% = &H64

110 CALL IBPPC (BRD0%,V%)

GPIB-PC User Manual

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©National Instruments Corp.

Section Four A

BASICA/QuickBASIC GPIB-PC Function Calls

BASICA/QuickBASIC

IBRD

BASICA/QuickBASIC

IBRD

Purpose:

Format:

Read data to string

CALL IBRD (BD%,RD$)

Remarks: BD%specifies a device or an interface board. RD$

identifies the storage buffer for data bytes that are read

from the GPIB.

The IBRDfunction reads from 1 to 255 bytes of data from a

GPIB device. In QuickBASIC the IBRDfunction reads

from 1 to 32K bytes of data from a GPIB device.

Device IBRD Function:

When BD% specifies a device, the following board steps are performed

automatically to read from the device:

1. The IBCMD function is called to address the device to talk and

the access board to listen.

2. The board IBRDfunction is called to read the data from the

device, as explained in the following discussion.

3. The IBCMD function is called to unaddress the access board

and unaddress all devices using the Untalk and Unlisten

commands.

Other command bytes may be sent as necessary.

When the device IBRDfunction returns, IBSTA%holds the latest

device status; IBCNT% is the actual number of data bytes read from the

device; and IBERR%is the first error detected if the ERR bit in IBSTA%

is set.

Board IBRD Function:

When BD% specifies an interface board, the IBRD function attempts to

read from a GPIB device that is assumed to already be properly

initialized and addressed.

If the access board is CIC, the IBCMD function must be called prior to

IBRD to address a device to talk and the board to listen. Otherwise, the

device on the GPIB that is the CIC must perform the addressing.

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BASICA/QuickBASIC GPIB-PC Function Calls

Section Four A

If the access board is Active Controller, the board is first placed in

Standby Controller state with ATN off and remains there after the read

operation is completed. Otherwise, the read operation commences

immediately.

An EADR error results if the board is CIC but has not been addressed to

listen with the IBCMDfunction. An EABO error results if the board is

not the CIC and is not addressed to listen within the time limit. An

EABO error also results if the device that is to talk is not addressed

and/or the operation does not complete for whatever reason within the

time limit.

The board IBRDoperation terminates on any of the following events:

•

Allocated buffer becomes full;

Error is detected;

•

Time limit is exceeded;

END message is detected;

EOS character is detected (if this option is enabled); or

Device Clear (DCL) or Selected Device Clear (SDC)

command is received from another device which is the CIC.

After termination, IBCNT%contains the number of bytes read. A short

count can occur on any event but the first.

Device Example:

1. Read 56 bytes of data from the device TAPE%.

100 REM Perform device read.

110 RD$ = SPACE$(56)

120 CALL IBRD (TAPE%,RD$)

130 REM Check IBSTA% to see how the read

140 REM terminated on: CMPL, END, TIMO, or

150 REM ERR.

160 REM Data is stored in RD$.

170 REM All unaddressing has been done.

GPIB-PC User Manual

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©National Instruments Corp.

Section Four A

BASICA/QuickBASIC GPIB-PC Function Calls

Board Examples:

1. Read 56 bytes of data from a device at talk address &H4C

(ASCII L) and then unaddress it (the GPIB-PC listen address is

&H20 or ASCII space).

100 CMD$ = "? L" ' UNL MLA TAD

110 CALL IBCMD (BRD0%,CMD$)

120 RD$ = SPACE$(56)

130 CALL IBRD (BRD0%,RD$)

140 REM Check IBSTA% to see how the read

150 REM terminated on: CMPL, END, TIMO or

160 REM ERR.

170 REM Data is stored in RD$.

180 REM Unaddress the Talker and Listener.

190 CMD$ = "_?" ' UNT UNL

200 CALL IBCMD (BRD0%,CMD$)

2. To terminate the read on an end-of-string character, see IBEOS

examples.

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BASICA/QuickBASIC GPIB-PC Function Calls

Section Four A

BASICA/QuickBASIC

IBRDA

BASICA/QuickBASIC

IBRDA

Purpose:

Format:

Read data asynchronously to string

CALL IBRDA (BD%,RD$)

Remarks: BD%specifies a device or an interface board. RD$

identifies the storage buffer for data bytes that are read

from the GPIB.

The IBRDAfunction reads from 1 to 255 bytes of data from

a GPIB device. In QuickBASIC the IBRDAfunction reads

from 1 to 32K bytes of data from a GPIB device.

IBRDAis used in place of IBRD when the application

program must perform other functions while processing the

GPIB I/O operation. IBRDAreturns after starting the I/O

operation. If the number of bytes to read is small and the

bytes are transmitted quickly by the GPIB device, the

operation may complete on the initial call. In this case,

the CMPL bit will be set in IBSTA%. If the operation does

not complete on the initial call, you should monitor the

IBSTA%variable after subsequent calls (usually IBWAIT

calls) to know that the I/O is completed. When CMPL

becomes set in IBSTA%, indicating that the I/O is

complete, the number of bytes read is reported in the

IBCNT%variable.

Device IBRDA Function:

When BD% specifies a device, the following board steps are performed

automatically to read from the device:

1. The IBCMD function is called to address the device to talk and

the access board to listen.

2. The board IBRDAfunction is called to read the data from the

device, as explained in the following discussion.

Other command bytes may be sent as necessary.

When the device IBRDAfunction returns, IBSTA%holds the latest

device status; IBERR%is the first error detected, if the ERR bit in

IBSTA%is set.

GPIB-PC User Manual

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©National Instruments Corp.

Section Four A

BASICA/QuickBASIC GPIB-PC Function Calls

When the I/O finally completes and the CMPL bit is set in IBSTA%, the

handler automatically unaddresses all devices.

Board IBRDA Function:

When BD% specifies an interface board, the IBRDA function attempts to

read from a GPIB device that is assumed to be already properly

initialized and addressed.

If the board is CIC, the IBCMDfunction must be called prior to IBRDA

to address the device to talk and the board to listen. Otherwise, the

device on the GPIB that is the CIC must perform the addressing.

If the board is Active Controller, the board is first placed in Standby

Controller state with ATN off and remains there after the read operation

is completed. Otherwise, the read operation commences immediately.

An EADR error results if the interface board is CIC but has not

addressed itself as a Listener with the IBCMD function.

IBRDAreturns immediately even when no error condition exists. When

you notice the CMPL bit set in IBSTA%, indicating that the I/O is

complete, IBCNT% indicates the number of bytes received.

Between the issuing of the IBRDA call and the corresponding CMPL,

other GPIB function calls to this device or to any other device with the

same access board, or any board calls to the access board itself, will

return the error EOIP, with the following exceptions:

• IBSTOP

• IBWAIT

• IBONL

to cancel the asynchronous I/O;

to monitor other GPIB conditions; or

to cancel the I/O and reset the interface.

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BASICA/QuickBASIC GPIB-PC Function Calls

Section Four A

Device Example:

1. Read 56 bytes of data from the device TAPE% while performing

other processing.

100 REM Perform device read.

110 RD$ = SPACE$(56)

120 CALL IBRDA (TAPE%,RD$)

130 MASK% = &H4100

' TIMO CMPL

140 REM Perform other processing here then

150 REM wait for I/O completion or a

160 REM timeout.

170 CALL IBWAIT (TAPE%,MASK%)

180 REM Check IBSTA% to see how the read

190 REM terminated on: CMPL, END, TIMO, or

200 REM ERR. If CMPL is not set,

210 REM continue processing.

220 IF (IBSTA% AND &H100) = 0 GOTO 130

230 REM Data is stored in RD$.

240 REM All unaddressing has been done.

GPIB-PC User Manual

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©National Instruments Corp.

Section Four A

BASICA/QuickBASIC GPIB-PC Function Calls

Board Examples:

1. Read 56 bytes of data from a device at talk address &H4C

(ASCII L) and then unaddress it (the GPIB-PC listen address is

&H20 or ASCII space).

100 REM Perform addressing in preparation

110 REM for board read

120 CMD$ = "? L"

' UNL MLA TAD

130 CALL IBCMD (BRD0%,CMD$)

140 REM Perform board read.

150 RD$ = SPACE$(56)

160 CALL IBRDA (BRD0%,RD$)

170 REM Perform other processing here, then

180 REM wait for I/O completion or a

190 REM timeout.

200 MASK% = &H4100

' TIMO CMPL

210 CALL IBWAIT (BRD0%,MASK%)

220 REM Check IBSTA% to see how the read

230 REM terminated on: CMPL, END, TIMO, or

240 REM ERR (not done here). Data is

250 REM stored in RD$.

260 REM Unaddress the Talker and Listener.

270 CMD$ = "_?"

' UNT UNL

280 CALL IBCMD (BRD0%,CMD$)

2. To terminate the read on an end-of-string character, see IBEOS

examples.

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BASICA/QuickBASIC GPIB-PC Function Calls

Section Four A

BASICA/QuickBASIC

IBRDF

BASICA/QuickBASIC

IBRDF

Purpose:

Format:

Read data from GPIB into file

CALL IBRDF (BD%,FLNAME$)

Remarks: BD%specifies a device or an interface board. FLNAME$is

the filename under which the data is stored. FLNAME$

may be up to 50 characters long, including a drive and path

designation.

IBRDF automatically opens the file as a binary file (as

opposed to a character file). If the file does not exist,

IBRDFcreates it. On exit, IBRDFcloses the file.

An EFSO error results if it is not possible to open, create,

seek, write, or close the file being referenced.

Device IBRDF Function:

When BD% specifies a device, the device IBRD function is called to

read from the device.

When the device IBRDFfunction returns, IBSTA%holds the latest

device status; IBCNT% is the actual number of data bytes read from the

device, modulo 65,536; and IBERR%is the first error detected, if the

ERR bit in IBSTA%is set.

Board IBRDF Function:

When BD%specifies an interface board, the board IBRDfunction is

called, which attempts to read from a GPIB device that is assumed to

already be properly initialized and addressed.

An EADR error results if the board is CIC but has not been addressed to

listen with the IBCMDfunction. An EABO error results if the board is

not the CIC and is not addressed to listen within the time limit. An

EABO error also results if the device that is to talk is not addressed

and/or the operation does not complete for whatever reason within the

time limit.

GPIB-PC User Manual

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©National Instruments Corp.

Section Four A

BASICA/QuickBASIC GPIB-PC Function Calls

The board IBRDFoperation terminates on any of the following events:

•

Error is detected;

Time limit is exceeded;

END message is detected;

EOS character is detected (if this option is enabled); or

Device Clear (DCL) or Selected Device Clear (SDC)

command is received from another device which is the CIC.

After termination, IBCNT%contains the number of bytes read, modulo

65,536.

Device Example:

1. Read data from the device RDR%into the file RDGSon disk

drive B.

100 REM Perform device read.

110 FLNAME$ = "B:RDGS"

120 CALL IBRDF (RDR%,FLNAME$)

130 REM Check IBSTA% and IBCNT% to see how

140 REM the read completed (not done here).

150 REM All addressing and unaddressing has

160 REM been done.

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BASICA/QuickBASIC GPIB-PC Function Calls

Section Four A

Board Example:

1. Read data from a device at talk address &H4C (ASCII L) to

the file RDGSon the current disk drive and then unaddress it

(the GPIB-PC listen address is &H20 or ASCII space).

100 REM Perform addressing in preparation

110 REM for board read.

120 CMD$ = "?L " ' UNL TAD MLA

130 CALL IBCMD (BRD0%,CMD$)

140 REM Perform board read.

150 FLNAME$ = "RDGS"

160 CALL IBRDF (BRD0%,FLNAME$)

170 REM Check IBSTA% and IBCNT% to see how

180 REM the read completed (not done here).

190 REM Unaddress the Talker and Listener.

200 CMD$ = "_?" ' UNT UNL

210 CALL IBCMD (BRD0%,CMD$)

GPIB-PC User Manual

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©National Instruments Corp.

Section Four A

BASICA/QuickBASIC GPIB-PC Function Calls

BASICA/QuickBASIC

IBRDI

BASICA/QuickBASIC

IBRDI

Purpose:

Format:

Read data to integer array

BASICA and QuickBASIC Version 1.0:

Call IBRDI (BD%,IARR%(0),CNT%)

QuickBASIC Version 2.0 and 3.0:

Call IBRDI (BD%, VARPTR(IARR%(0)), CNT%)

QuickBASIC Version 4.0:

Call IBRDI (BD%, IARR%(), CNT%)

Remarks: BD%specifies a device or an interface board. IARR%

specifies an integer array into which data is read from the

GPIB. CNT%specifies the maximum number of bytes to be

read. VARPTRreturns the address of the array so that it

may be passed to the language interface.

Read up to CNT%bytes of data from BD%and store in

IARR%. As the data is read, each byte pair is treated as an

integer and stored in IARR%.

Unlike IBRD, because IBRDI stores the data directly into

an integer array, no integer conversion is needed on the

data that has been read for arithmetic operations to be

performed on it.

Refer to the IBRDfunction and to the information about

BASICA and QuickBASIC GPIB-PC I/O Functions at the

beginning of this section.

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BASICA/QuickBASIC GPIB-PC Function Calls

Section Four A

Device Example:

1. Read 56 bytes of data from the device TAPE%and store in the

integer array RD%.

100 CNT% = 56

110 REM Array size is equal to CNT% divided

120 REM by 2.

130 DIM RD% (28)

140 CALL IBRDI (TAPE%,RD%(0),CNT%)

QuickBASIC Version 2.0 or 3.0,

replace line 140 with:

140 CALL IBRDI (TAPE%,VARPTR(RD%(0)),CNT%)

QuickBASIC Version 4.0,

replace line 140 with:

140 CALL IBRDI (TAPE%,RD%(), CNT%)

GPIB-PC User Manual

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©National Instruments Corp.

Section Four A

BASICA/QuickBASIC GPIB-PC Function Calls

Board Examples:

1. Read 56 bytes of data into the integer array RD% from a device

at talk address &H4C (ASCII L) and then unaddress it (the

GPIB-PC listen address is &H20 or ASCII space).

100 CMD$ = "? L" ' UNL MLA TAD

110 CALL IBCMD (BRD0%,CMD$)

120 CNT% = 56

130 REM Array size is equal to CNT% divided

140 REM by 2.

150 DIM RD% (28)

160 CALL IBRDI (BRD0%,RD%(0),CNT%)

170 REM Check IBSTA% to see how the read

180 REM terminated on: CMPL, END, TIMO, or

190 REM ERR.

200 REM Data is stored in RD$.

210 REM Unaddress the Talker and Listener.

220 CMD$ = "_?" ' UNT UNL

230 CALL IBCMD (BRD0%,CMD$)

QuickBASIC Version 2.0 and 3.0,

replace line 160 with:

160 CALL IBRDI (TAPE%,VARPTR(RD%(0)),CNT%)

QuickBASIC Version 4.0,

replace line 160 with:

160 CALL IBRDI (BD%,RD%(), CNT%)

2. To terminate the read on an end-of-string character, see IBEOS

examples.

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BASICA/QuickBASIC GPIB-PC Function Calls

Section Four A

BASICA/QuickBASIC

IBRDIA

BASICA/QuickBASIC

IBRDIA

Purpose:

Format:

Read data asynchronously to integer array

BASICA and QuickBASIC Version 1.0:

Call IBRDIA (BD%,IARR%(0),CNT%)

QuickBASIC Version 2 and 3:

Call IBRDIA (BD%, VARPTR(IARR%(0)),CNT%)

QuickBASIC Version 4:

Call IBRDIA (BD%, IARR%(), CNT%)

Remarks: BD%specifies a device or an interface board. IARR%

specifies an integer array into which data is read

asynchronously from the GPIB. CNT%specifies the

maximum number of bytes to be read. VARPTRreturns the

address of the array so that it may be passed to the

language interface.

This is a special case of the IBRDA function, which stores

a maximum of 255 data bytes into a character string

variable in BASICA. In QuickBASIC this function stores

up to 32K data bytes into a character string variable.

Read asynchronously up to CNT%bytes of data from BD%

and store in IARR%. As the data is read, each byte pair is

treated as an integer and stored in IARR%.

GPIB-PC User Manual

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Section Four A

BASICA/QuickBASIC GPIB-PC Function Calls

Unlike IBRDA, IBRDIAstores the data directly into an

integer array. No integer conversion is needed on the data

that has been read for arithmetic operations to be performed

on it.

NOTE: Do not pass dynamic arrays to the asynchronous

functions IBRDIAand IBWRTIA, since the QuickBASIC

environment might move them around in memory during an

I/O operation.

Refer to the IBRDAfunction and to the BASICA and

QuickBASIC GPIB-PC I/O Functions at beginning of this

section.

Device Example:

1. Read 56 bytes of data into the integer array RD%from the

device TAPE% while performing other processing.

100 REM Perform device read.

110 CNT% = 56

120 REM Array size is equal to CNT% divided

130 REM by 2.

140 DIM RD% (28)

150 CALL IBRDIA (TAPE%,RD%(0),CNT%)

160 MASK% = &H4100

' TIMO CMPL

170 REM Perform other processing here then

180 REM wait for I/O completion or a

190 REM timeout.

200 CALL IBWAIT (TAPE%,MASK%)

210 REM Check IBSTA% to see how the read

220 REM terminated on: CMPL, END, TIMO, or

230 REM ERR.

240 REM If CMPL or ERR is not set,

250 REM continue processing.

260 IF (IBSTA% AND &H8100) = 0 GOTO 160

270 REM Data is stored in RD%

280 REM All unaddressing has been done.

QuickBASIC Version 2.0 or 3.0,

replace line 150 with:

150 CALL IBRDIA (TAPE%,VARPTR(RD%(0)),CNT%)

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BASICA/QuickBASIC GPIB-PC Function Calls

Section Four A

QuickBASIC Version 4.0,

replace line 150 with:

150 CALL IBRDIA (TAPE%,RD%(),CNT%)

Board Examples:

1. Read 56 bytes of data into the integer array RD% from a device

at talk address &H4C (ASCII L) and then unaddress it (the

GPIB-PC listen address is &H20 or ASCII space).

100 REM Perform addressing in preparation

110 REM for board read.

120 CMD$ = "? L" ' UNL MLA TAD

130 CALL IBCMD (BRD0%,CMD$)

140 REM Perform board read.

150 CNT% = 56

160 REM Array size is equal to CNT% divided

170 REM by 2.

180 DIM RD% (28)

190 CALL IBRDIA (BRD0%,RD%(0),CNT%)

200 MASK% = &H4100

' TIMO CMPL

210 REM Perform other processing here then

220 REM wait for I/O completion or a

230 REM timeout.

240 CALL IBWAIT (BRD0%,MASK%)

250 REM Check IBSTA% to see how the read

260 REM terminated on: CMPL, END, TIMO, or

270 REM ERR.

280 REM If CMPL or ERR are not set,

290 REM continue processing.

300 IF (IBSTA% AND &H8100) = 0 GOTO 200

310 REM Data is stored in RD$.

320 REM Unaddress the Talker and Listener.

330 CMD$ = "_?" ' UNT UNL

340 CALL IBCMD (BRD0%,CMD$)

GPIB-PC User Manual

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©National Instruments Corp.

Section Four A

BASICA/QuickBASIC GPIB-PC Function Calls

QuickBASIC Version 2.0 or 3.0,

replace line 190 with:

190 CALL IBRDIA (TAPE%,VARPTR(RD%(0)),CNT%)

QuickBASIC Version 4.0,

replace line 190 with:

190 CALL IBRDIA (BD%,RD%(),CNT%)

2. To terminate the read on an end-of-string character, see IBEOS

examples.

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BASICA/QuickBASIC GPIB-PC Function Calls

Section Four A

BASICA/QuickBASIC

IBRPP

BASICA/QuickBASIC

IBRPP

Purpose:

Format:

Conduct a Parallel Poll

CALL IBRPP (BD%,PPR%)

Remarks: BD%specifies a device or an interface board. PPR%

identifies the variable where the parallel poll response byte

is stored.

Device IBRPP Function:

When BD% specifies a device, all devices on its GPIB are polled in

parallel using the access board of that GPIB. This is done by executing

the board IBRPP function with the appropriate access board specified.

Board IBRPP Function:

When BD%specifies a board, the IBRPP function causes the identified

board to conduct a parallel poll of previously configured devices by

sending the IDY message (ATN and EOI both asserted) and reading the

response from the GPIB data lines.

An ECIC error results if the GPIB-PC is not CIC. If the GPIB-PC is

Standby Controller, it takes control and asserts ATN (becomes Active)

prior to polling. It remains Active Controller afterward.

In the examples that follow, some of the GPIB commands and addresses

are coded as printable ASCII characters. When the values to be sent

over the GPIB correspond to printable ASCII characters, this is the

simplest means of specifying the values. Refer to Appendix A for

conversions of numeric values to ASCII characters.

GPIB-PC User Manual

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©National Instruments Corp.

Section Four A

BASICA/QuickBASIC GPIB-PC Function Calls

Device Example:

1. Remotely configure the device LCRMTR%to respond positively

on DI03 if its individual status bit is 1, and then parallel poll all

configured devices.

100 V% = %H6A

110 CALL IBPPC (LCRMTR%,V%)

120 CALL IBRPP (LCRMTR%,PPR%)

Board Examples:

1. Remotely configure the device BRD0% at listen address &H23

(ASCII #) to respond positively on DI03 if its individual status

bit is 1, and then parallel poll all configured devices.

100 REM Send LAD, PPC, PPE, and UNL.

110 CMD$ = "#" + CHR$(&H05) + "j?"

120 CALL IBCMD (BRD0%,CMD$)

130 CALL IBRPP (BRD0%,PPR%)

2. Disable and unconfigure all GPIB devices from parallel polling

using the PPU (&H15) command.

100 CMD$ = CHR$(&H15)

' PPU

110 CALL IBCMD (BRD0%,CMD$)

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BASICA/QuickBASIC GPIB-PC Function Calls

Section Four A

BASICA/QuickBASIC

IBRSC

BASICA/QuickBASIC

IBRSC

Purpose:

Format:

Request or release System Control

CALL IBRSC (BD%,V%)

Remarks: BD%specifies an interface board. If V%is non-zero,

functions requiring System Controller capability are

subsequently allowed. If V% is zero, functions requiring

System Controller capability are disallowed.

The IBRSCfunction is used to enable or disable the

capability of the GPIB-PC to send the Interface Clear

(IFC) and Remote Enable (REN) messages to GPIB

devices using the IBSICand IBSRE functions

respectively. The interface board must not be System

Controller to respond to Interface Clear sent by another

Controller.

In most applications, the GPIB-PC will always be the

System Controller. In other applications, the GPIB-PC will

never be the System Controller. In either case, the IBRSC

function is used only if the computer is not going to be

System Controller for the duration of the program

execution. While the IEEE-488 standard does not

specifically allow schemes in which System Control can be

passed dynamically from one device to another, the IBRSC

function would be used in such a scheme.

When IBRSC is called and an error does not occur, the

previous value of ist is stored in IBERR%.

Refer also to Table 2.1.

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Section Four A

BASICA/QuickBASIC GPIB-PC Function Calls

Board Example:

1. Request to be System Controller if the interface board BRD0%

is not currently so designated.

100 V% = 1

' Any non-zero value will do.

110 CALL IBRSC (BRD0%,V%)

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BASICA/QuickBASIC GPIB-PC Function Calls

Section Four A

BASICA/QuickBASIC

IBRSP

BASICA/QuickBASIC

IBRSP

Purpose:

Format:

Return serial poll byte

CALL IBRSP (BD%,SPR%)

Remarks: BD%specifies a device. SPR% is the variable in which the

poll response is stored.

The IBRSP function is used to serially poll one device and

obtain its status byte or to obtain a previously stored status

byte. If bit 6 (the &H40 bit) of the response is set, the

status response is positive, i.e., the device is requesting

service. On exit, all devices are unaddressed.

When automatic serial polling is enabled, the specified

device may have been polled previously. If it has been

polled and a positive response was obtained, the RQS bit of

that device's status word is set, and in this case a call to

IBRSPreturns the previously acquired status byte. If the

RQS bit of the status word is not set when IBRSPis called,

the device is serially polled.

When a poll is actually conducted, the specific sequence

of events is as follows:

1. IBCMDsends the following commands:

•

Unlisten (UNL);

Talk address of the device;

Secondary address of the device, if applicable;

Listen address of the access board;

Secondary address of the access board, if applicable; and

Serial Poll Enable (SPE).

Other command bytes may be sent as necessary.

2. IBRDreads one response from the device and stores it

in SPR%.

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Section Four A

BASICA/QuickBASIC GPIB-PC Function Calls

3. IBCMDsends the following commands:

•

Untalk (UNT) and Unlisten (UNL); and

Serial Poll Disable (SPD).

The interpretation of the response in SPR%, other than the

RQS bit, is device-specific. For example, the polled

device might set a particular bit in the response byte to

indicate

that it has data to transfer, and another bit to indicate a

need for reprogramming. Consult the device documentation

for interpretation of the response byte.

Refer to IBCMDand IBRDfor additional information.

Device Example:

1. Obtain the Serial Poll response (SPR) byte from the device

TAPE%.

100 CALL IBRSP (TAPE%,SPR%)

110 REM The application program would then

120 REM analyze the response in SPR%.

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BASICA/QuickBASIC GPIB-PC Function Calls

Section Four A

BASICA/QuickBASIC

IBRSV

BASICA/QuickBASIC

IBRSV

Purpose:

Format:

Request service and/or set or change the serial poll status

byte

CALL IBRSV (BD%,V%)

Remarks: BD%specifies an interface board. V% specifies the response

or status byte the GPIB-PC provides when serially polled

by another device that is the GPIB CIC. If bit 6 (the &H40

bit) is set, the GPIB-PC additionally requests service from

the Controller by asserting the GPIB SRQ line.

The IBRSVfunction is used to request service from the

Controller using the Service Request (SRQ) signal and to

provide a system dependent status byte when the Controller

serially polls the GPIB-PC.

When IBRSV is called and an error does not occur, the

previous value of ist is stored in IBERR%.

Refer also to Table 2.1.

Board Examples:

1. Set the Serial Poll status byte to &H41, which simultaneously

requests service from an external CIC.

100 V% = &H41

110 CALL IBRSV (BRD0%,V%)

2. Change the status byte as in Example 1, without requesting

service.

100 V% = &H01 ' New status byte value.

110 CALL IBRSV (BRD0%,V%)

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Section Four A

BASICA/QuickBASIC GPIB-PC Function Calls

BASICA/QuickBASIC

IBSAD

BASICA/QuickBASIC

IBSAD

Purpose:

Format:

Change or disable Secondary Address

CALL IBSAD (BD%,V%)

Remarks: BD%specifies a device or an interface board. If V%is a

number between &H6O and &H7E, that number becomes

the secondary GPIB address device or interface board. If

V%is &H7F or zero, secondary addressing is disabled.

IBSADis needed only to alter the value from its

configuration setting.

The assignment made by this function remains in effect

until IBSADis called again, the IBONLor IBFIND

function is called, or the system is rebooted.

When IBSAD is called and an error does not occur, the

previous value of ist is stored in IBERR%.

Device IBSAD Function:

When BD% specifies a device, the function enables or disables extended

GPIB addressing for the device. When secondary addressing is enabled,

IBSADrecords the secondary GPIB address of that device to be used in

subsequent device I/O function calls.

Board IBSAD Function:

When BD%specifies an interface board, the IBSAD function enables or

disables extended GPIB addressing and, when enabled, assigns the

secondary address of the GPIB-PC.

Refer also to IBPAD, IBONL, and Table 2.1.

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BASICA/QuickBASIC GPIB-PC Function Calls

Section Four A

Device Examples:

1. Change the secondary GPIB address of the device PLOTTER%

from its current value to &H6A.

100 V% = &H6A

110 CALL IBSAD (PLOTTER%,V%)

2. Disable secondary addressing for the device DVM%.

100 V% = 0

' 0 or &H7F may be used.

110 CALL IBSAD (DVM%,V%)

Board Examples:

1. Change the secondary GPIB address of the interface board

BRD0%from its current value to &H6A.

100 V% = &H6A

110 CALL IBSAD (BRD0%,V%)

2. Disable secondary addressing for the interface board BRD0%.

100 V% = 0 ' 0 or &H7F may be used.

110 CALL IBSAD (BRD0%,V%)

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Section Four A

BASICA/QuickBASIC GPIB-PC Function Calls

BASICA/QuickBASIC

IBSIC

BASICA/QuickBASIC

IBSIC

Purpose:

Format:

Send interface clear for 100 microseconds

CALL IBSIC (BD%)

Remarks: BD% specifies an interface board.

The IBSICfunction causes the GPIB-PC to assert the IFC

signal for at least 100 microseconds, provided the GPIB-PC

has System Controller capability. This action initializes

the GPIB and makes the interface board CIC and Active

Controller with ATN asserted, and is generally used when a

bus fault condition is suspected.

The IFC signal resets only the GPIB interface functions of

bus devices and not the internal device functions. Device

functions are reset with the Device Clear (DCL) and

Selected Device Clear (SDC) commands. To determine

the effect of these messages, consult the device

documentation.

The ESAC error occurs if the GPIB-PC does not have

System Controller capability.

Refer also to IBRSC.

Board Example:

1. Initialize the GPIB and become CIC and Active Controller at

the beginning of a program.

100 CALL IBSIC (BRD0%)

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BASICA/QuickBASIC GPIB-PC Function Calls

Section Four A

BASICA/QuickBASIC

IBSRE

BASICA/QuickBASIC

IBSRE

Purpose:

Format:

Set or clear the Remote Enable line

CALL IBSRE (BD%,V%)

Remarks: BD%specifies an interface board. If V%is non-zero the

Remote Enable (REN) signal is asserted. If V%is zero the

signal is unasserted.

The IBSREfunction turns the REN signal on and off. REN

is used by devices to select between local and remote

modes of operation. REN enables the remote mode. A

device does not actually enter remote mode until it

receives its listen address.

The ESAC error occurs if the GPIB-PC is not System

Controller.

When IBSRE is called and an error does not occur, the

previous value of V% is stored in IBERR%.

Refer also to IBRSCand Table 2.1.

Board Examples:

1. Place the device at listen address &H23 (ASCII #) in remote

mode with local ability to return to local mode.

100 V% = 1 ' Any non-zero value will do.

110 CALL IBSRE (BRD0%,V%)

120 CMD$ = "#"

' LAD

130 CALL IBCMD (BRD0%,CMD$)

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Section Four A

BASICA/QuickBASIC GPIB-PC Function Calls

2. To exclude the local ability of the device to return to local

mode, send the Local Lockout (LLO or &H11) command or

include it in the command string at 120 in Example 1.

100 CMD$ = CHR$(&H11)

110 CALL IBCMD (BRD0%,CMD$)

100 CMD$ = "#" + CHR$(&H11)

110 CALL IBCMD (BRD0%,CMD$)

3. Return all devices to local mode.

100 V% = 0 ' Set REN to false

110 CALL IBSRE (BRD0%,V%)

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BASICA/QuickBASIC GPIB-PC Function Calls

Section Four A

BASICA/QuickBASIC

IBSTOP

BASICA/QuickBASIC

IBSTOP

Purpose:

Format:

Abort asynchronous operation

CALL IBSTOP (BD%)

Remarks: BD% specifies a device or an interface board.

IBSTOPterminates any asynchronous read, write, or

command operation in progress.

Device IBSTOP Function:

If BD%specifies a device, IBSTOP attempts to terminate any unfinished

asynchronous I/O operation to that device that had been started with a

device function for that device.

If the operation is aborted before completion, the ERR bit in the status

word is set and an EABO error is returned. No error indication results if

the operation successfully completes before IBSTOPis called.

Board IBSTOPFunction:

If BD%specifies a board, IBSTOP attempts to terminate any unfinished

asynchronous I/O operation that had been started with a board function

using that board.

If the operation is aborted before completion, the ERR bit in the status

word is set and an EABO error is returned. No error indication results if

the operation successfully completes before IBSTOPis called.

Device Example:

1. Stop any asynchronous operations associated with the device

RDR%.

100 CALL IBSTOP (RDR%)

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Section Four A

BASICA/QuickBASIC GPIB-PC Function Calls

Board Example:

1. Stop any asynchronous operations associated with the interface

board BRD0%.

100 CALL IBSTOP (BRD0%)

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BASICA/QuickBASIC GPIB-PC Function Calls

Section Four A

BASICA/QuickBASIC

IBTMO

BASICA/QuickBASIC

IBTMO

Purpose:

Format:

Change or disable time limit

CALL IBTMO (BD%,V%)

Remarks: BD% specifies a device or an interface board. V%is a code

specifying the time limit as follows:

Value

of V%

Minimum

Timeout

disabled

10 µsec

30 µsec

100 µsec

300µsec

1 msec

3 msec

10 msec

30 msec

100 msec

300 msec

1 sec

3 sec

10 sec

30 sec

100 sec

300 sec

1000 sec

NOTE: If V%is zero, no limit is in effect.

IBTMOis needed only to alter the value from its

configuration setting.

The assignment made by this function remains in effect

until IBTMOis called again, the IBONLor IBFIND

function is called, or the system is rebooted.

GPIB-PC User Manual

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Section Four A

BASICA/QuickBASIC GPIB-PC Function Calls

The IBTMO function changes the length of time that the

following functions wait for the embedded I/O operation to

finish or for the specified event to occur before returning

with a timeout indication:

• IBCMD,

• IBRD,

• IBRDI,

• IBWRT, or

• IBWRTI.

The IBTMO function also changes the length of time that

device functions wait for commands to be accepted. If a

device does not accept commands within the time limit,

the EBUS error will be returned.

When IBTMO is called and an error does not occur, the

previous value of ist is stored in IBERR%.

Device IBTMO Function:

When BD% specifies a device, the new time limit is used in subsequent

device functions directed to that device.

Board IBTMO Function:

When BD% specifies a board, the new time limit is used in subsequent

board functions directed to that board.

Refer also to IBWAITand to Table 2.1.

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BASICA/QuickBASIC GPIB-PC Function Calls

Section Four A

Device Example:

1. Change the time limit for calls involving the device TAPE%to

approximately 300 msec.

100 V% = 10

110 CALL IBTMO (TAPE%,V%)

Board Example:

1. Change the time limit for calls directed to the interface board

BRD0%to approximately 10 msec.

100 V% = 7

110 CALL IBTMO (BRD0%,V%)

GPIB-PC User Manual

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Section Four A

BASICA/QuickBASIC GPIB-PC Function Calls

BASICA/QuickBASIC

IBTRAP

BASICA/QuickBASIC

IBTRAP

Purpose:

Format:

Alter applications monitor trap and display modes

CALL IBTRAP (MASK%,DISPLAY%)

Remarks: MASK% specifies a bit mask with the same bit assignments

as the mask used with the function IBWAIT. Each MASK%

bit is set, cleared to trap, or cleared not to trap,

respectively, when the corresponding bit appears in the

status word after a GPIB call. If all the bits are set, then

every GPIB call is trapped.

MODE%determines when the recording and trapping occur.

The valid values are:

Turn monitor off. No recording or trapping

occurs.

Turn record on. All calls are recorded but

no trapping occurs.

Turn record and trap on. All calls are

recorded and the monitor is displayed

whenever a trap condition occurs.

If an error occurs during this call, the ERR bit of IBSTA

will be set and IBERRwill be one of the following:

Applications monitor not installed.

Invalid monitor mode.

4 (EARG) IBTRAPnot supported by installed

handler.

Otherwise, IBERRwill contain the previous mask value.

Refer to Section Six for more information.

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BASICA/QuickBASIC GPIB-PC Function Calls

Section Four A

Device Example:

1. Configure applications monitor to record and trap on SRQ or

CMPL.

100 MASK% = &H1100

110 MODE% = 3

'SRQ or CMPL

'Record and trap on

120 CALL IBTRAP (MASK%, MODE%)

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Section Four A

BASICA/QuickBASIC GPIB-PC Function Calls

BASICA/QuickBASIC

IBTRG

BASICA/QuickBASIC

IBTRG

Purpose:

Format:

Trigger selected device

CALL IBTRG (BD%)

Remarks: BD% specifies a device.

The IBTRG function addresses and triggers the specified

device, then unaddresses all devices on the GPIB.

IBTRGcalls the board IBCMDfunction to send the

following commands:

•

Listen address of the device;

Secondary address of the device, if applicable;

Group Execute Trigger (GET); and

Untalk (UNT) and Unlisten (UNL).

Other command bytes may be sent as necessary.

Refer to the IBCMDfunction for additional information.

Device Example:

1. Trigger the device ANALYZ%.

100 CALL IBTRG (ANALYZ%)

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BASICA/QuickBASIC GPIB-PC Function Calls

Section Four A

BASICA/QuickBASIC

IBWAIT

BASICA/QuickBASIC

IBWAIT

Purpose:

Format:

Wait for selected event

CALL IBWAIT (BD%,MASK%)

Remarks: BD%specifies a device or an interface board. MASK%is a

bit mask with the same bit assignments as the status word,

IBSTA%. Each MASK%bit is set or cleared to wait or not

wait, respectively, for the corresponding event to occur.

The IBWAITfunction is used to monitor the events

selected in MASK% and to delay processing until any of

them occur. These events and bit assignments are shown in

Table 4A.4.

IBWAITalso updates all conditions of the status word,

which may be read in the IBSTA% variable.

If MASK%=0 or MASK%=&H8000 (the ERR bit), the function

returns immediately.

If the TIMO bit is 0, or the time limit is set to 0 with the

IBTMO function, timeouts are disabled. Disabling timeouts

should be done only when setting MASK%=0 or when it is

certain the selected event will occur; otherwise, the

processor may wait indefinitely for the event to occur.

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Section Four A

BASICA/QuickBASIC GPIB-PC Function Calls

Table 4A.4 - Wait Mask Layout

Mnemonic

ERR

TIMO

END

SRQI

RQS

CMPL

LOK

Bit

Hex

8000

4000

2000

1000

800

100

Description

GPIB error

Time limit exceeded

GPIB-PC detected END or EOS

SRQ on

Device requesting service

I/O completed

GPIB-PC is in lockout state

GPIB-PC is in remote state

GPIB-PC is CIC

REM

CIC

ATN

Attention is asserted

GPIB-PC is Talker

GPIB-PC is Listener

GPIB-PC is in device trigger state

GPIB-PC is in device clear state

TACS

LACS

DTAS

DCAS

Device IBWAIT Function:

When BD% specifies a device, only the ERR, TIMO, END, RQS, and

CMPL bits of the wait mask and status word are applicable. On an

IBWAIT for RQS, each time the GPIB SRQ line is asserted, the access

board of the specified device serially polls all devices on its GPIB and

saves the responses, until the status byte returned by the device being

waited for indicates that it was the device requesting service (bit &H40

is set in the status byte). Note that an IBWAIT on RQS should only be

done on those devices that respond to serial polls. If the TIMO bit of the

mask is also set, IBWAITreturns if SRQ is not asserted within the

device's timeout period. The serial polls are conducted with the board

functions IBCMDand IBRD.

Board IBWAITFunction:

When BD% specifies a board, all bits of the wait mask and status word

are applicable except RQS.

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BASICA/QuickBASIC GPIB-PC Function Calls

Section Four A

Device Example:

1. Wait indefinitely for the device LOGGER%to request service.

100 MASK% = &H800

' RQS

110 CALL IBWAIT (LOGGER%,MASK%)

Board Examples:

1. Wait for a service request or a timeout.

100 MASK% = &H5000

' TIMO SRQI

110 CALL IBWAIT (BD%,MASK%)

120 REM Check IBSTA% here to see which

130 REM occurred.

2. Update the current status for IBSTA%.

100 MASK% = 0

110 CALL IBWAIT (BD%,MASK%)

3. Wait indefinitely until control is passed from another CIC.

100 MASK% = &H20

' CIC

110 CALL IBWAIT (BD%,MASK%)

4. Wait indefinitely until addressed to talk or listen by another

CIC.

100 MASK% = &H0C

' TACS LACS

110 CALL IBWAIT (BD%,MASK%)

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Section Four A

BASICA/QuickBASIC GPIB-PC Function Calls

BASICA/QuickBASIC

IBWRT

BASICA/QuickBASIC

IBWRT

Purpose:

Format:

Write data from string

CALL IBWRT (BD%,WRT$)

Remarks: BD%specifies a device or an interface board. WRT$

contains the data to be sent over the GPIB.

In BASICA, the IBWRTfunction writes from 1 to 255 bytes

of data to a GPIB device. In QuickBASIC, the IBWRT

function writes from 1 to 32K bytes of data to a GPIB

device.

Device IBWRT Function:

When BD% specifies a device, the following board steps are performed

automatically to write to the device:

1. The IBCMD function is called to address the device to listen

and the access board to talk.

2. The board IBWRTfunction is called to write the data to the

device, as explained in the following discussion.

3. The IBCMD function is called to unaddress the access board

using the Untalk command and all devices using the Unlisten

command.

Other command bytes may be sent as necessary.

When the device IBWRTfunction returns, IBSTA%holds the latest

device status; IBCNT% is the actual number of data bytes written to the

device; and IBERR%is the first error detected if the ERR bit in IBSTA%

is set.

Board IBWRT Function:

When BD% specifies an interface board, the IBWRT function attempts to

write to a GPIB device that is assumed to already be properly initialized

and addressed.

If the access board is CIC, the IBCMD function must be called prior to

IBWRT to address the device to listen and the board to talk. Otherwise,

the device on the GPIB that is the CIC must perform the addressing.

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BASICA/QuickBASIC GPIB-PC Function Calls

Section Four A

If the access board is Active Controller, the board is first placed in

Standby Controller state with ATN off and remains there after the write

operation is completed. Otherwise, the write operation commences

immediately.

An EADR error results if the board is CIC but has not been addressed to

talk with the IBCMDfunction. An EABO error results if the board is not

the CIC and is not addressed to talk within the time limit. An EABO

error also results if the operation does not complete for whatever reason

within the time limit. An ENOL error occurs if there are no listeners on

the bus when the data bytes are sent.

Note that if you want to send an EOS character at the end of your data

string, you must place it there explicitly. See Device Example 2.

The board IBWRToperation terminates on any of the following events:

•

All bytes are transferred;

Error is detected;

Time limit is exceeded; or

Device Clear (DCL) or Selected Device Clear (SDC)

command is received from another device which is the CIC.

After termination, IBCNT%contains the number of bytes written. A

short count can occur on any event but the first.

Device Examples:

1. Write 10 instruction bytes to the device DVM%.

100 WRT$ = "F3R1X5P2G0"

110 CALL IBWRT (DVM%,WRT$)

2. Write 5 instruction bytes terminated by a carriage return and a

linefeed to the device PTR%. Linefeed is the device's EOS

character.

100 WRT$ = "IP2X5" + CHR$(&H0D) + CHR$(&H0A)

110 CALL IBWRT (PTR%,WRT$)

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Section Four A

BASICA/QuickBASIC GPIB-PC Function Calls

Board Example:

1. Write 10 instruction bytes to a device at listen address &H2F

(ASCII /) and then unaddress it (the GPIB-PC talk address is

&H40 or ASCII @).

100 REM Perform addressing.

110 CMD$ = "?@/"

' UNL MTA LAD

120 CALL IBCMD (BRD0%,CMD$)

130 REM Perform board write.

140 WRT$ = "F3R1X5P2G0"

150 CALL IBWRT (BRD0%,WRT$)

160 REM Unaddress the Talker and Listener.

170 CMD$ = "_?"

' UNT UNL

180 CALL IBCMD (BRD0%,CMD$)

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BASICA/QuickBASIC GPIB-PC Function Calls

Section Four A

BASICA/QuickBASIC

IBWRTA

BASICA/QuickBASIC

IBWRTA

Purpose:

Format:

Write data asynchronously from string

CALL IBWRTA (BD%,WRT$)

Remarks: BD%specifies a device or an interface board. WRT$

contains the data to be sent over the GPIB.

This is a special case of the IBWRTA function which in

BASICA writes a maximum of 255 bytes from a character

string to the GPIB. In QuickBASIC the function IBWRTA

writes a maximum of 32K bytes of data from a character

string to the GPIB.

IBWRTAis used in place of IBWRT when the application

program must perform other functions while processing the

GPIB I/O operation. IBWRTAreturns after starting the I/O

operation. If the number of bytes to write is small and the

bytes are received quickly by the GPIB device, the

operation may complete on the initial call. In this case,

the CMPL bit will be set in IBSTA%. If the operation does

not complete on the initial call, you should monitor the

IBSTA%variable after subsequent calls (usually IBWAIT

calls) to know that the I/O is completed. When CMPL

becomes set in IBSTA%, indicating that the I/O is

complete, the number of bytes written is reported in the

IBCNT%variable.

Device IBWRTA Function:

When BD% specifies a device, the following board steps are performed

automatically to write to the device:

1. The IBCMD function is called to address the device to listen

and the assigned interface board to talk.

2. The board IBWRTAfunction is called to write the data to the

device, as explained in the following discussion.

Other command bytes may be sent as necessary.

GPIB-PC User Manual

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©National Instruments Corp.

Section Four A

BASICA/QuickBASIC GPIB-PC Function Calls

When the device IBWRTAfunction returns, IBSTA%holds the latest

device status and IBERR%is the first error detected, if the ERR bit in

IBSTA% is set. When the I/O finally completes and the CMPL bit is set

in IBSTA%, the handler automatically unaddresses all devices.

Board IBWRTAFunction:

When BD%specifies an interface board, the IBWRTA function attempts

to write to a GPIB device that is assumed to be already properly

initialized and addressed.

If the board is CIC, the IBCMDfunction must be called prior to IBWRTA

to address the device to listen and the board to talk. Otherwise, the

device on the GPIB that is the CIC must perform the addressing.

If the board is Active Controller, the board is first placed in Standby

Controller state with ATN off and remains there after the write operation

is completed. Otherwise, the write operation commences immediately.

An EADR error results if the board is CIC but has not been addressed to

talk with the IBCMDfunction. An ENOL error occurs if there are no

listeners on the bus when the data bytes are sent.

Note that if you want to send an eos character at the end of your data

string, you must place it there explicitly.

Between the issuing of the IBWRTA call and the corresponding CMPL,

other GPIB function calls to this device or to any other device with the

same access board, or any board calls to the access board itself, will

return the error EOIP, with the following exceptions:

• IBSTOP- to cancel the asynchronous I/O;

• IBWAIT- to monitor other GPIB conditions; or

• IBONL - to cancel the I/O and reset the interface.

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BASICA/QuickBASIC GPIB-PC Function Calls

Section Four A

Device Example:

1. Write 10 instruction bytes to the device DVM% while performing

other processing.

100 WRT$ = "F3R1X5P2G0"

110 CALL IBWRTA (DVM%,WRT$)

120 MASK% = &H4100

'TIMO CMPL

130 REM Perform other processing here then

140 REM wait for I/O completion or a

150 REM timeout.

160 CALL IBWAIT (DVM%,MASK%)

170 REM Check IBSTA% to see how the write

180 REM terminated on: CMPL, END, TIMO, or

190 REM ERR. If CMPL is not set,

200 REM continue processing.

210 IF (IBSTA% AND &H100) = 0 GOTO 130

Board Example:

1. Write 10 instruction bytes to a device at listen address &H2F

(ASCII /), while testing for a high priority event to occur, and

then unaddress it (the GPIB-PC talk address is &H40 or ASCII

@).

100 REM Perform addressing in preparation

110 REM for board write.

120 CMD$ = "?@/"

' UNL MTA LAD

130 CALL IBCMD (BRD0%,CMD$)

140 REM Perform board asynchronous write.

150 WRT$ = "F3R1X5P2G0"

160 CALL IBWRTA (BRD0%,WRT$)

170 REM Perform other processing here then

180 REM wait for I/O completion or a

190 REM timeout.

200 MASK% = &H4100

' TIMO CMPL

210 CALL IBWAIT (BRD0%,MASK%)

220 REM Unaddress the Talker and Listener.

230 CMD$ = "_?"

' UNT UNL

240 CALL IBCMD (BRD0%,CMD$)

GPIB-PC User Manual

4A-92

©National Instruments Corp.

Section Four A

BASICA/QuickBASIC GPIB-PC Function Calls

BASICA/QuickBASIC

IBWRTF

BASICA/QuickBASIC

IBWRTF

Purpose:

Format:

Write data from file

CALL IBWRTF (BD%,FLNAME$)

Remarks: BD%specifies a device or an interface board. FLNAME$

indicates the filename from which the data is written to the

GPIB. FLNAME$may be up to 50 characters long,

including a drive and path designation.

IBWRTFautomatically opens the file. On exit, IBWRTF

closes the file.

An EFSO error results if it is not possible to open, seek,

read, or close the file.

Device IBWRTF Function:

When BD% specifies a device, the device IBWRT function is called to

write to the device.

When the device IBWRTFfunction returns, IBSTA%holds the latest

device status; IBCNT% is the actual number of data bytes written to the

device, modulo 65,536; and IBERR%is the first error detected, if the

ERR bit in IBSTA%is set.

Board IBWRTFFunction:

When BD%specifies an interface board, the board IBWRTfunction is

called, which attempts to write to a GPIB device that is assumed to be

already properly initialized and addressed.

An EADR error results if the board is CIC but has not been addressed to

talk with the IBCMDfunction. An EABO error results if the board is not

the CIC and is not addressed to talk within the time limit. An EABO

error also results if the operation does not complete for whatever reason

within the time limit. An ENOL error occurs if there are no listeners on

the bus when the data bytes are sent.

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BASICA/QuickBASIC GPIB-PC Function Calls

Section Four A

The board IBWRTFoperation terminates on any of the following events:

•

All bytes sent;

Error is detected;

Time limit is exceeded; or

Device Clear (DCL) or Selected Device Clear (SDC)

command is received from another device which is the CIC.

After termination, IBCNT%contains the number of bytes written,

modulo 65,536.

Device Example:

1. Write data to the device RDR%from the file Y.DATon the

current disk drive.

100 FLNAME$ = "Y.DAT"

110 CALL IBWRTF (RDR%,FLNAME$)

Board Example:

1. Write data to the device at listen address &H2C (ASCII ,) from

the file Y.DAT on the current drive, and then unaddress the

interface board BRD0%.

100 REM Perform addressing in preparation

110 REM for board write.

120 CMD$ = "?@,"

' UNL MTA LAD

130 CALL IBCMD (BRD0%,CMD$)

140 REM Perform board write.

150 FLNAME$ = "Y.DAT"

160 CALL IBWRTF (BRD0%,FLNAME$)

170 REM Unaddress the Talker and Listener.

180 CMD$ = "_?"

' UNT UNL

190 CALL IBCMD (BRD0%,CMD$)

GPIB-PC User Manual

4A-94

©National Instruments Corp.

Section Four A

BASICA/QuickBASIC GPIB-PC Function Calls

BASICA/QuickBASIC

IBWRTI

BASICA/QuickBASIC

IBWRTI

Purpose:

Format:

Write data from integer array

BASICA and QuickBASIC Version 1.0:

Call IBWRTI (BD%,IARR%(0),CNT%)

QuickBASIC Version 2.0 and 3.0:

Call IBWRTI (BD%, VARPTR(IARR%(0)),

CNT%)

QuickBASIC Version 4.0:

Call IBWRTI (BD%, IARR%(), CNT%)

Remarks: BD%specifies a device or an interface board. IARR%is an

integer array from which data is written to the GPIB. CNT%

specifies the maximum number of bytes to be written.

Write CNT%bytes of data from IARR%to the GPIB. The

data, stored as two-byte integers in IARR%, is sent in low-

byte, high-byte order to the GPIB.

This is a special case of the IBWRT function, which writes

a maximum of 255 bytes from a character string to the

GPIB. This function is useful when those bytes are stored

in integer format.

Refer to the IBWRTfunction and to the information about

BASICA/QuickBASIC GPIB-PC I/O Functions at the

beginning of this section. Refer also to IBWRTIA.

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BASICA/QuickBASIC GPIB-PC Function Calls

Section Four A

Device Examples:

1. Write 10 instruction bytes from the integer array WRT%to the

device DVM%.

100 DIM WRT%(4)

110 WRT%(0) = ASC("F") + ASC("3") * 256

120 WRT%(1) = ASC("R") + ASC("1") * 256

130 WRT%(2) = ASC("X") + ASC("5") * 256

140 WRT%(3) = ASC("P") + ASC("2") * 256

150 WRT%(4) = ASC("G") + ASC("0") * 256

160 CNT% = 10

170 CALL IBWRTI (DVM%,WRT%(0),CNT%)

QuickBASIC Version 2.0 and 3.0,

replace line 170 with:

CALL IBWRTI (PTR%,VARPTR(WRT%(0)),CNT%)

QuickBASIC Version 4.0,

replace line 170 with:

CALL IBWRTI (BD%,WRT%(),CNT%)

2. Write 5 instruction bytes from integer array WRT% terminated by

a carriage return and a linefeed to device PTR%. Linefeed is

the device's eos character.

100 DIM WRT%(3)

110 WRT%(0) = ASC("I") + ASC("P") * 256

120 WRT%(1) = ASC("2") + ASC("X") * 256

130 WRT%(2) = ASC("5") + &H0D * 256

140 WRT%(3) = &H0A

150 CNT% = 7

160 CALL IBWRTI (PTR%,WRT%(0),CNT%)

GPIB-PC User Manual

4A-96

©National Instruments Corp.

Section Four A

BASICA/QuickBASIC GPIB-PC Function Calls

Board Example:

1. Write 10 instruction bytes from the integer array WRT%to a

device at listen address &H2F (ASCII /) and then unaddress it

(the GPIB-PC talk address is &H40 or ASCII @).

100 REM Perform addressing.

120 CMD$ = "?@/"

' UNL MTA LAD

130 CALL IBCMD (BRD0%,CMD$)

140 REM Perform board write.

150 DIM WRT%(4)

160 WRT%(0) = ASC("F") + ASC("3") * 256

170 WRT%(1) = ASC("R") + ASC("1") * 256

180 WRT%(2) = ASC("X") + ASC("5") * 256

190 WRT%(3) = ASC("P") + ASC("2") * 256

200 WRT%(4) = ASC("G") + ASC("0") * 256

210 CNT% = 10

220 CALL IBWRTI (BRD0%,WRT%(0),CNT%)

230 REM Unaddress all Talkers and

240 REM Listeners.

250 CMD$ = "_?"

' UNT UNL

260 CALL IBCMD (BRD0%,CMD$)

QuickBASIC Version 2.0 and 3.0,

replace line 220 with:

CALL IBWRTI (PTR%,VARPTR(WRT%(0)),CNT%)

QuickBASIC Version 4.0,

replace line 220 with:

CALL IBWRTI (BD%,WRT%(),CNT%)

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BASICA/QuickBASIC GPIB-PC Function Calls

Section Four A

BASICA/QuickBASIC

IBWRTIA

BASICA/QuickBASIC

IBWRTIA

Purpose:

Format:

Write data asynchronously from integer array

BASICA and QuickBASIC Version 1.0:

Call IBWRTIA (BD%,IARR%(0),CNT%)

QuickBASIC Version 2.0 and 3.0:

Call IBWRTIA (BD%, VARPTR(IARR%(0)),

CNT%)

QuickBASIC Version 4.0:

Call IBWRTIA (BD%, IARR%(), CNT%)

Remarks: BD%specifies a device or an interface board. IARR%is an

array from which integer data is written. CNT% specifies

the maximum number of bytes to be written.

Write asynchronously CNT%bytes of integer data from

IARR%to the GPIB. The data is sent in low-byte, high-

byte order.

This is a special case of the IBWRTA function, which

writes, in BASICA, a maximum of 255 bytes from a

character string to the GPIB. In QuickBASIC, this function

writes a maximum of 32 K bytes of data from a character

string to the GPIB.

Refer to the IBWRTAfunction and to the information about

BASICA/QuickBASIC GPIB I/O Functions at the beginning

of this section.

GPIB-PC User Manual

4A-98

©National Instruments Corp.

Section Four A

BASICA/QuickBASIC GPIB-PC Function Calls

NOTE: Do not pass dynamic arrays to the asynchronous functions

IBRDIAand IBWRTIA, since the QuickBASIC environment might

move them around in memory during an I/O operation.

Device Example:

1. Write 10 instruction bytes from integer array to the device

DVM%while performing other processing.

100 DIM WRT%(4)

110 WRT%(0) = ASC("F") + ASC("3") * 256

120 WRT%(1) = ASC("R") + ASC("1") * 256

130 WRT%(2) = ASC("X") + ASC("5") * 256

140 WRT%(3) = ASC("P") + ASC("2") * 256

150 WRT%(4) = ASC("G") + ASC("0") * 256

160 CNT% = 10

170 CALL IBWRTIA (DVM%,WRT%(0),CNT%)

180 MASK% = &H4100

' TIMO CMPL

190 REM Perform other processing here then

200 REM wait for I/O completion or timeout.

210 CALL IBWAIT (DVM%,MASK%)

220 REM Check IBSTA% to see how the write

230 REM terminated on: CMPL, END, TIMO, or

240 REM ERR.

250 REM If CMPL is not set, continue

260 REM processing.

270 IF (IBSTA% AND &H100) = 0 GOTO 190

QuickBASIC Version 2.0 and 3.0,

replace line 170 with:

CALL IBWRTIA (PTR%,VARPTR(WRT%(0)),CNT%)

QuickBASIC Version 4.0, replace line 170 with:

CALL IBWRTIA (BD%,WRT%(),CNT%)

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BASICA/QuickBASIC GPIB-PC Function Calls

Section Four A

Board Example:

1. Write 10 instruction bytes from the integer array WRT%to a

device at listen address &H2F (ASCII /) and then unaddress it

(the GPIB-PC talk address is &H40 or ASCII @).

100 REM Perform addressing.

110 CMD$ = "?@/"

' UNL MTA LAD

120 CALL IBCMD (BRD0%,CMD$)

130 REM Perform board write.

140 DIM WRT%(4)

150 WRT%(0) = ASC("F") + ASC("3") * 256

160 WRT%(1) = ASC("R") + ASC("1") * 256

170 WRT%(2) = ASC("X") + ASC("5") * 256

180 WRT%(3) = ASC("P") + ASC("2") * 256

190 WRT%(4) = ASC("G") + ASC("0") * 256

200 CNT% = 10

210 CALL IBWRTIA (BRD0%,WRT%(0),CNT%)

220 REM Perform other processing here then

230 REM wait for I/O completion or timeout.

240 MASK% = &H4100

' TIMO CMPL250

260 CALL IBWAIT (BRD0%,MASK%)

270 REM Unaddress the Talker and Listener.

280 CMD$ = "_?"

' UNT UNL

290 CALL IBCMD (BRD0%,CMD$)

For QuickBASIC Version 2.0 and 3.0,

replace line 210 with:

CALL IBWRTIA (PTR%,VARPTR(WRT%(0)),CNT%)

For QuickBASIC Version 4.0,

replace line 210 with:

CALL IBWRTIA (BD%,WRT%(),CNT%)

GPIB-PC User Manual

4A-100

©National Instruments Corp.

Section Four A

BASICA/QuickBASIC GPIB-PC Function Calls

BASICA/QuickBASIC GPIB Programming

Examples

This section illustrates the programming steps that could be used to

program a representative IEEE-488 instrument from your personal

computer using the GPIB-PC handler functions. The applications are

written in BASICA and QuickBASIC. The target instrument is a digital

voltmeter (DVM). This instrument is otherwise unspecified (that is, it is

not a DVM manufactured by any particular manufacturer). The purpose

here is to explain how to use the handler to execute certain

programming and control sequences and not how to determine those

sequences.

Because the instructions that are sent to program a device as well as the

data that might be returned from the device are called device

dependent messages, the format and syntax of the messages used in

this example are unique to this device. Furthermore, the interface

messages or bus commands that must be sent to devices will also vary,

but to a lesser degree. The exact sequence of messages to program and

to control a particular device are contained in its documentation.

For example, the following sequence of actions is assumed to be

necessary to program this DVM to make and return measurements of a

high frequency AC voltage signal in the autoranging mode:

1. Initialize the GPIB interface circuits of the DVM so that it can

respond to messages.

2. Place the DVM in remote programming mode and turn off front

panel control.

3. Initialize the internal measurement circuits.

4. Program the DVM to the proper function (F3 for high frequency

AC volts), range (R7 for autoranging), and trigger source (T3

for external or remote).

5. For each measurement:

a. Send the GET (Group Execute Trigger) command to trigger

the DVM.

b. Wait until the DVM asserts Service Request (SRQ) to

indicate that the measurement is ready to be read.

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BASICA/QuickBASIC GPIB-PC Function Calls

Section Four A

c. Serially poll the DVM to determine if the measured data is

valid (status byte = &HC0) or if a fault condition exists

(the &H40 bit and another bit of the status byte, other than

&H80, are set).

d. If the data is valid, read 16 bytes from the DVM.

6. End the session.

The example programs that follow are based on these assumptions:

•

The GPIB-PC is the designated System Active Controller of the

GPIB.

•

There is no change to the GPIB-PC default hardware settings.

The only changes made to the software parameters are those

necessary to define the device DVM at primary address 3.

•

There is only one GPIB-PC in use, which is designated GPIB0.

Its primary listen and talk addresses are &H20 (ASCII space

character) and &H40 (ASCII @ character), respectively.

GPIB-PC User Manual

4A-102

©National Instruments Corp.

Section Four A

BASICA/QuickBASIC GPIB-PC Function Calls

BASICA Example Program - Device

BASICA - Using device function calls.

100 REM You must merge this code with DECL.BAS.

105 REM

110 REM Assign a unique identifier to device and

120 REM store in variable DVM%.

125 REM

130

140

BDNAME$ = "DVM"

CALL IBFIND (BDNAME$,DVM%)

145 REM

150 REM Check for error on IBFIND call.

155 REM

160

IF DVM% < 0 THEN GOTO 2000

170 REM

180 REM Clear the device.

185 REM

190

CALL IBCLR (DVM%)

195 REM

200 REM Check for an error on each GPIB call to

210 REM be safe.

215 REM

220

IF IBSTA% < 0 THEN GOTO 3000

230 REM

240 REM Write the function, range, and trigger

250 REM source instructions to the DVM.

255 REM

260

270

WRT$ = "F3R7T3" : CALL IBWRT (DVM%,WRT$)

IF IBSTA% < 0 THEN GOTO 3000

280 REM

290 REM Trigger the device.

295 REM

300

310

CALL IBTRG (DVM%)

IF IBSTA% < 0 THEN GOTO 3000

320 REM

330 REM Wait for the DVM to set RQS or for a

340 REM timeout; if the current time limit is too

350 REM short, use IBTMO to change it.

355 REM

360

370

MASK% = &H4800 : CALL IBWAIT (DVM%,MASK%)

IF (IBSTA% AND &HC000) <> 0 THEN GOTO 3000

380 REM

390 REM Since neither a timeout nor an error

400 REM occurred, IBWAIT must have returned on

410 REM RQS. Next, serial poll the device.

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BASICA/QuickBASIC GPIB-PC Function Calls

Section Four A

415 REM

420

CALL IBRSP (DVM%,SPR%)

430

IF IBSTA% < 0 THEN GOTO 3000

440 REM

450 REM Now test the status byte (SPR%).

460 REM If SPR% is &HC0, the DVM has valid data

470 REM to send; otherwise, it has a fault

475 REM condition to report.

480 REM

490

IF SPR% <> &HC0 THEN GOTO 4000

500 REM

510 REM If the data is valid, read the

520 REM measurement.

525 REM

530

540

RD$ = SPACE$(16) : CALL IBRD (DVM%,RD$)

IF IBSTA% < 0 THEN GOTO 3000

550 REM

560 REM To close out a programming sequence,

570 REM reset the device, and call IBONL to take

575 REM the device offline.

580 REM

585

590

CALL IBCLR (DVM%)

V% = 0 : CALL IBONL (DVM%,V%) : STOP

2000

2010

2020

2030

2040

REM A routine at this location would

REM notify you that the IBFIND call

REM failed, and refer you to the handler

REM software configuration procedures.

PRINT "IBFIND ERROR" : STOP

3000

3010

3020

3030

3040

3050

3060

3070

3080

3090

REM An error checking routine at this

REM location would among other things,

REM check IBERR to determine the exact

REM cause of the error condition and then

REM take action appropriate to the

REM application. For errors during data

REM transfers, IBCNT may be examined to

REM determine the actual number of bytes

REM transferred.

PRINT "GPIB ERROR" : STOP

4000

4010

4020

4030

4040

5000

REM A routine at this location would

REM analyze the fault code returned in the

REM DVM's status byte and take appropriate

REM action.

PRINT "DVM ERROR" : STOP

END

GPIB-PC User Manual

4A-104

©National Instruments Corp.

Section Four A

BASICA/QuickBASIC GPIB-PC Function Calls

BASICA Example Program - Board

BASICA - Using board function calls

100 REM You must merge this code with DECL.BAS.

105 REM

110 REM Assign a unique identifier to board 0 and

120 REM store in the variable BRD0%.

125 REM

130

140

BDNAME$ = "GPIB0"

CALL IBFIND (BDNAME$,BRD0%)

145 REM

150 REM Check for error on IBFIND call.

153 REM

155

IF BRD0% < 0 THEN GOTO 2000

160 REM

165 REM Send the Interface Clear (IFC) message to

170 REM all devices.

175 REM

180

CALL IBSIC (BRD0%)

190 REM

200 REM Check for an error on each GPIB call.

215 REM

220

IF IBSTA% < 0 THEN GOTO 3000

230 REM

240 REM Turn on the Remote Enable (REN) signal.

245 REM

250

260

V% = 1 : CALL IBSRE (BRD0%,V%)

IF IBSTA% < 0 THEN GOTO 3000

270 REM

280 REM Inhibit front panel control with the

290 REM Local Lockout (LLO) command, place the

300 REM DVM in remote mode by addressing it to

310 REM listen, send the Device Clear (DCL)

320 REM message to clear internal device

330 REM functions, and address the GPIB0 to talk.

345 REM

350

360

CMD$ = CHR$(&H11)+ "#" +CHR$(&H14)+ "@"

CALL IBCMD (BRD0%,CMD$)

370

IF IBSTA% < 0 THEN GOTO 3000

380 REM

390 REM Write the function, range, and trigger

400 REM source instructions to the DVM.

405 REM

410

420

WRT$ = "F3R7T3" : CALL IBWRT (BRD0%,WRT$)

IF IBSTA% < 0 THEN GOTO 3000

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BASICA/QuickBASIC GPIB-PC Function Calls

Section Four A

430 REM

440 REM Send the GET message to trigger a

450 REM measurement reading.

455 REM

460

470

CMD$ = CHR$(&H8) : CALL IBCMD (BRD0%,CMD$)

IF IBSTA% < 0 THEN GOTO 3000

480 REM

490 REM Wait for the DVM to set SRQ or for a

500 REM timeout; if the current time limit is too

510 REM short, use IBTMO to change it.

515 REM

520

530

540

MASK% = &H5000

CALL IBWAIT (BRD0%, MASK%)

IF (IBSTA% AND &HC000) <> 0 THEN GOTO 3000

550 REM

560 REM Since neither a timeout nor an error

570 REM occurred, IBWAIT must have returned on

580 REM SRQ. Next do a serial poll. First

590 REM unaddress bus devices and send the Serial

600 REM Poll Enable (SPE) command, then send the

610 REM DVM's talk address and the GPIB-PC listen

615 REM address &H20 (ASCII space).

620 REM

630

CMD$ = "?_" + CHR$(&H18) + "C "

CALL IBCMD (BRD0%,CMD$)

640

650

IF IBSTA% < 0 THEN GOTO 3000

660 REM

670 REM Now read the status byte. If it is &HC0,

680 REM the DVM has valid data to send;

690 REM otherwise, it has a fault condition to

695 REM report.

700 REM

710

RD$ = SPACE$(1) : CALL IBRD (BRD0%,RD$)

IF IBSTA% < 0 THEN GOTO 3000

720

730

IF ASC(RD$) <> &HC0 THEN GOTO 4000

731 REM

732 REM If more than one device were attached to

734 REM the bus, it would be necessary to

735 REM explicitly check the &H40 bit of the DVM

736 REM status word to be sure that another

738 REM device had not been responsible

740 REM for asserting SRQ. Complete

750 REM the serial poll by sending the Serial

760 REM Poll Disable (SPD) message.

765 REM

770

780

CMD$ = CHR$(&H19) : CALL IBCMD (BRD0%,CMD$)

IF IBSTA% < 0 THEN GOTO 3000

GPIB-PC User Manual

4A-106

©National Instruments Corp.

Section Four A

BASICA/QuickBASIC GPIB-PC Function Calls

790 REM

800 REM Since the DVM and GPIB-PC are still

810 REM addressed to talk and listen, the

815 REM measurement can be read

820 REM as follows.

825 REM

830

RD$ = SPACE$(16) : CALL IBRD (BRD0%,RD$)

IF IBSTA% < 0 THEN GOTO 3000

840

850 REM

860 REM To close out a programming sequence, send

870 REM IFC to initialize the bus and call the

880 REM IBONL function to place the GPIB-PC

885 REM offline.

890 REM

900

910

CALL IBSIC (BRD0%)

V% = 0 : CALL IBONL (BRD0%,V%) : STOP

2000

2010

2015

2020

2040

REM A routine at this location would

REM notify you that the IBFIND call

REM failed, and refer you to the handler

REM software configuration procedures.

PRINT "IBFIND ERROR" : STOP

3000

3010

3020

3015

3030

3040

3050

3070

3075

3080

REM An error checking routine at this

REM location would, among other things,

REM check IBERR to determine the exact

REM cause of the error condition and then

REM take action appropriate to the

REM application. For errors during data

REM transfers, IBCNT may be examined to

REM determine the actual number of bytes

REM transferred.

PRINT "GPIB ERROR" : STOP

4000

4010

4015

4020

4040

5000

REM A routine at this location would

REM analyze the fault code returned in the

REM DVM's status byte

REM and take appropriate action.

PRINT "DVM ERROR" : STOP

END

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BASICA/QuickBASIC GPIB-PC Function Calls

QuickBASIC Example Program - Device

QuickBASIC - Using device function calls.

Section Four A

COMMON SHARED IBSTA%, IBERR%, IBCNT%

REM Assign a unique identifier to device

REM and store in variable DVM%.

REM

BDNAME$ = "DVM"

CALL IBFIND (BDNAME$,DVM%)

REM

REM Check for error on IBFIND call.

REM

IF DVM% < 0 THEN GOSUB FIND-ERROR:

REM

REM Clear the device.

REM

CALL IBCLR (DVM%)

REM

REM Check for an error on each GPIB call

REM to be safe.

REM

IF IBSTA% < 0 THEN GOSUB GPIB-ERROR:

REM

REM Write the function, range, and trigger

REM source instructions to the DVM.

REM

WRT$ = "F3R7T3" : CALL IBWRT (DVM%,WRT$)

IF IBSTA% < 0 THEN GOSUB GPIB-ERROR:

REM

REM Trigger the device.

REM

CALL IBTRG (DVM%)

IF IBSTA% < 0 THEN GOSUB GPIB-ERROR:

REM

REM Wait for the DVM to set RQS or for a

REM timeout; if the current time limit

REM is too short, use IBTMO to change it.

REM

MASK% = &H4800 : CALL IBWAIT (DVM%,MASK%)

IF (IBSTA% AND &HC000) <> 0 THEN GOSUB GPIB-ERROR:

REM

REM Since neither a timeout nor an error

REM occurred, IBWAIT must have returned

REM on RQS. Next, serial poll the device.

REM

GPIB-PC User Manual

4A-108

©National Instruments Corp.

Section Four A

BASICA/QuickBASIC GPIB-PC Function Calls

CALL IBRSP (DVM%,SPR%)

IF IBSTA% < 0 THEN GOSUB GPIB-ERROR:

REM

REM Now test the status byte (SPR%).

REM If SPR% is &HC0, the DVM has valid

REM data to send; otherwise, it has a

REM fault condition to report.

REM

IF SPR% <> &HC0 THEN GOSUB DEVICE-ERROR:

REM

REM If the data is valid, read the

REM measurement.

REM

RD$ = SPACE$(16) : CALL IBRD (DVM%,RD$)

IF IBSTA% < 0 THEN GOSUB GPIB-ERROR:

REM

REM To close out a programming sequence,

REM reset the device, and call IBONL

REM to place the device offline.

REM

CALL IBCLR (DVM%)

V% = 0

CALL IBONL (DVM%,V%) : STOP

END

IBFIND-ERROR:

REM A routine at this location would notify

REM you that the IBFIND call failed, and

REM refer you to the handler software

REM configuration procedures.

PRINT "IBFIND ERROR" : STOP

GPIB-ERROR:

REM An error checking routine at this

REM location would, among other things,

REM check IBERR to determine the exact cause of

REM the error condition and then take action

REM appropriate to the application.

REM For errors during data transfers,

REM IBCNT may be examined to determine the actual

REM number of bytes transferred.

PRINT "GPIB ERROR" : STOP

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BASICA/QuickBASIC GPIB-PC Function Calls

Section Four A

DEVICE-ERROR:

REM A routine at this location would analyze

REM the fault code returned in the DVM's status

REM byte and take appropriate action.

PRINT "DVM ERROR" : STOP

END

GPIB-PC User Manual

4A-110

Section Four A

BASICA/QuickBASIC GPIB-PC Function Calls

QuickBASIC Example Program - Board

QuickBASIC - Using board function calls.

COMMON SHARED IBSTA%, IBERR%, IBCNT%

REM

REM Assign a unique identified to board 0 and

REM store in variable BRD0%.

REM

BDNAME$ = "GPIB0"

CALL IBFIND (BDNAME$,BRD0%)

REM

REM Check for error on IBFIND call.

REM

IF BRD0% < 0 THEN GOSUB FIND-ERROR:

REM

REM Send the Interface Clear (IFC) message to

REM all devices.

REM

CALL IBSIC (BRD0%)

REM

REM Check for an error on each GPIB call

REM to be safe.

REM

IF IBSTA% , 0 THEN GOSUB GPIB-ERROR:

REM

REM Turn on the Remote Enable (REN) signal.

REM

V% = 1 : CALL IBSRE (BRD0%,V%)

IF IBSTA% < 0 THEN GOSUB GPIB-ERROR:

REM

REM Inhibit fron panel control with the

REM Local Lockout (LLO) command, place the

REM DVM in remote by addressing it to listen,

REM send the Device Clear (DCL) message to clear

REM internal device functions, and address the

REM GPIB-PC to talk.

REM

CMD$ = CHR$(&H11)+"#" +CHR$(&H14)+"@"

CALL IBCMD (BRD0%,CMD$)

IF IBSTA% < 0 THEN GOSUB GPIB-ERROR:

REM

REM Write the function, range, and trigger

REM source instructions to the DVM

REM

WRT$ = "F3R7T3" : CALL IBWRT (BRD0%,WRT$)

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BASICA/QuickBASIC GPIB-PC Function Calls

Section Four A

IF IBSTA% < 0 THEN GOSUB GPIB-ERROR:

REM

REM Send the GET message to trigger a

REM measurement reading.

REM

CMD$ = CHR$(&H8) : CALL IBCMD (BRD0%,CMD$)

IF IBSTA% < 0 THEN GOSUB GPIB-ERROR:

REM

REM Wait for the DVM to set SRQ or for a

REM timeout; if the current time limit

REM is too short, use IBTMO to change it.

REM

MASK% = &H5000

CALL IBWAIT (BRD0%,MASK%)

IF (IBSTA% AND &HC000) <> 0 THEN GOSUB GPIB-

ERROR:

REM

REM Since neither a timeout nor an error

REM occurred, IBWAIT must have returned

REM on SRQ. Next do a serial poll.

REM First unaddress bus devices and send

REM the Serial Poll Enable (SPE) command,

REM then send the DVM's talk address and

REM the GPIB0 listen address &H20 (ASCII

REM space).

REM

CMD$ = "?_" + CHR$(&H18) + "C"

CALL IBCMD (BRD0%,CMD$)

IF IBSTA% < 0 THEN GOSUB GPIB-ERROR:

REM

REM Now read the status byte. If it is

REM &HC0, the DVM has a valid data to send;

REM otherwise, it has a fault condition

REM to report.

REM

RD$ = SPACE$(1) : CALL IBRD (BRD0%,RD$)

IF IBSTA% < 0 THEN GOSUB GPIB-ERROR:

IF ASC(RD$) <> &HC0 THEN GOSUB DEVICE-ERROR:

REM

REM If more than one device were attached to

REM the bus, it would be necessary to explicitly

REM check the &HC0 bit if the DVM status

REM word to be sure that another device had

REM not been responsible for asserting SRQ.

REM Complete the serial poll by sending

REM the Serial Poll Disable (SPD) message.

REM

GPIB-PC User Manual

4A-112

Section Four A

BASICA/QuickBASIC GPIB-PC Function Calls

CMD$ = CHR$(&H19) : CALL IBCMD (BRD0%,CMD$)

IF IBSTA% < 0 THEN GOSUB GPIB-ERROR:

REM

REM Since the DVM and GPIB-PC are

REM still addressed to talk and listen,

REM the measurement can be read as follows.

REM

RD$ = SPACE$(16) : CALL IBRD (BRD0%,RD$)

IF IBSTA% < 0 THEN GOSUB GPIB-ERROR:

REM

REM To close out a programming sequence,

REM send IFC to initialize the bus and

REM call the IBONL function to place the

REM GPIB-PC offline.

REM

CALL IBSIC (BRD0%)

V% = 0 : CALL IBONL (BRD0%,V%) : STOP

END

FIND-ERROR:

REM A routine at this location would

REM notify you that the IBFIND call

REM failed, and refer you to the

REM handler, software configuration

REM procedures.

PRINT "IBFIND ERROR" : STOP

GPIB-ERROR:

REM An error checking routine at this

REM location would, among other things,

REM check IBERR to determine the exact

REM cause of the error condition and

REM then take action appropriate to

REM the application. For errors during

REM data transfers, IBCNT may be

REM examined to determine the actual

REM number of bytes transferred.

PRINT "GPIB ERROR" : STOP

DEVICE-ERROR:

REM A routine at this location would

REM analyze the fault code returned in

REM the DVM's status byte and take

REM appropriate action.

PRINT "DVM ERROR" : STOP

END

©Natio_Dn_oa_wl_nI_lon_as_dtr_fu_rom_me_Wnt_ws_wC_.So_or_mp_a._nuals.4_cA_om-1_.1_A3_{ll Manuals Sea}G_rchP_AIB_nd-P_DC_owU_nls_oe_ar_d.Manual

Section Five - IBIC

The IEEE-488 Bus Interactive Control program (IBIC) allows you to

control and communicate with the GPIB through functions you enter at

the keyboard. This feature helps you establish communication with the

device, troubleshoot problems, and develop the application.

IBICfunctions include most of the GPIB-PC functions described in

Sections Three and Four, plus auxiliary functions used only by IBIC.

In IBIC, the user can send data and GPIB commands to a device from

the keyboard and display data on the screen received from a device.

After each GPIB-PC function is executed, the numeric value and

mnemonic representation of the status word IBSTAis displayed. The

byte count IBCNTand error code IBERRare also shown when

appropriate.

This interactive method of data input and data/status output is designed

to help you learn how to use the GPIB-PC functions to program your

device. Once you develop a sequence of steps that works successfully

for your system, you can easily incorporate the sequence into an

application program using the appropriate language and syntax

described in Section Four.

5-1

GPIB-PC User Manual

IBIC

Section Five

Running IBIC

The IBICprogram, IBIC.EXE, is an executable file that was copied

from the distribution diskette to a subdirectory called GPIB-PCwhen

you ran IBSTARTat installation.

To run IBIC, change directory to C:\GPIB-PCand enter:

C:\GPIB-PC>

ibic

National Instruments

Interface Bus Interactive Control

Program (IBIC)

ments, Inc.

Type "help" for help.

Use IBFIND to initially open a boa

rd or device.

Use SET to select an already opene d board or device.

Messages will appear on the screen that give you information about the

HELP, IBFIND, and SETcommands.

The first input prompt to IBICis a colon (:).

NOTE: In using IBIC, the four most important functions are the HELP,

IBFIND, IBWRT, and IBRDcommands.

GPIB-PC User Manual

5-2

Section Five

IBIC

Using HELP

The HELPfunction gives on-line information about IBICand the

functions available within the environment. This facility provides a

quick reference for checking the syntax and function of the GPIB call.

Using IBFIND

To execute any GPIB function, you must first use IBFINDto open the

device or board you wish to use. When the device or board is opened,

the symbolic name of that device or board is added to the prompt.

The following examples show IBFINDopening dev1(Example 1) and

gpib0 (Example 2). The user's inputs are italicized.

Example 1:

:ibfind dev1

dev1:

Example 2:

:ibfind gpib0

gpib0:

The name used with the IBFIND function must be a valid symbolic

name known by the handler. Both dev1and gpib0are default names

found in the handler. IBIC makes no distinction between uppercase

and lowercase.

5-3

GPIB-PC User Manual

IBIC

Section Five

Using IBWRT

The IBWRTcommand sends data from one GPIB device to another. For

example, to send a data string from the computer to a device called

dev1, the following command would suffice:

Example:

dev1: ibwrt "F3R5T1"

[0100] (cmpl)

This command sends the string "F3R5T1"to device called dev1. The

returned Status Word [0100] indicates a successful I/O completion,

while the Byte Count indicates that all six characters were sent from

the computer and received by the device.

Using IBRD

The IBRD command causes a GPIB device to receive data from another

GPIB device. The following example illustrates the use of the IBRD

function.

Example:

dev1:

ibrd 20

[2100] (end cmpl)

4E 44 43 56 28 30 30 30

2E 30 30 34 37 45 2B 30

0D 0A

N D C V ( 0 0 0

. 0 0 4 7 E + 0

• •

GPIB-PC User Manual

5-4

Section Five

IBIC

This command receives data from the device and displays it on the

screen in hexadecimal format, and provides its ASCII equivalent, along

with information about the data transfer such as the Status Word and the

Byte Count.

How to Exit IBIC

Typing eor qwill return you to DOS.

Important Programming Note

Some GPIB instruments require special termination characters or End of

String (EOS) characters to indicate to the device the end of

transmission. If your device requires any EOS characters, you must add

these to the end of the data string sent out by the IBWRT statement.

The following example illustrates the addition of the two most

commonly used EOS characters, the carriage return and the linefeed.

Example:

dev1: ibwrt "F3R5T1\r\n"

[0100] (cmpl)

The \rand \n represent the carriage return and linefeed characters

respectively. See Table 5.3 for a more detailed description on the

representation of non-printable characters.

5-5

GPIB-PC User Manual

IBIC

Section Five

Using SET

Use IBFINDto open each device or board. Once the device or board is

opened, use the auxiliary function SET to select which opened device

or board to access. SET changes the prompt to the new symbolic name.

Example:

dev1: set plotter

plotter:

This example assumes that IBCONF was used to give a device the

name plotter.

The following example summarizes the use of IBFINDand SETin a

typical program.

Example:

: ibfind dev1

dev1:

ibfind plotter

plotter: ibwrt "F3T7G0"

[0100] (cmpl)

plotter: set dev1

dev1: ibwrt "X7Y39G0"

[0100] (cmpl)

dev1:

GPIB-PC User Manual

5-6

Section Five

IBIC

IBICFunctions and Syntax

IBIC displays the following information about each function call

immediately after that call:

• IBRDand IBRDA data messages are displayed on the screen in

hex and ASCII formats.

•

The global variables IBSTA, IBCNT, and IBERRare displayed

on the screen.

IBICand programming languages of Section Four differ in the syntax

of the function call. These differences are shown in Table 5.1. The

main differences are that IBWRT, IBWRTA, IBCMD, and IBCMDA

messages are entered as strings from the keyboard.

The BDunit descriptor is not explicitly a part of IBIC function syntax.

Before using any device or board, first call IBFINDto open that unit

and to pass the unit descriptor to IBIC. The screen prompt identifies

which of these opened units IBICwill use in subsequent calls. Use the

SETfunction to change from one of these units to another.

5-7

GPIB-PC User Manual

IBIC

Section Five

Other IBIC Functions and Syntax

Table 5.1 summarizes the GPIB-PC functions and syntax when called

from IBIC. Syntax rules for IBICare explained in the table notes.

Consult Section Four for detailed function descriptions and for syntax

rules of the programming language you will use.

Table 5.1 - Syntax of GPIB Functions in IBIC

Description

Function Function

Note

Syntax

Type

Change access board of device

ibbna

bname

ibcac [v]

ibclr

2,3

Become active controller

Clear specified device

Send commands from string

ibcmd

string

Send commands asynch from string ibcmda

string

Enable/disable DMA

ibdma [v]

2,3

Change/disable EOS message

Enable/disable END message

Return unit desciptor

ibeos v

ibeot [v]

ibfind

bdname

2,3

Go from active controller to standby ibgts [v]

Set/clear ist

Go to local

Place device online or offline

Change primary address

Pass control

ibist [v]

iblo

ibonl [v]

ibpad v

ibpct

2,3

Parallel poll configure

Read data

Read data asynchronously

Read data to file

ibppc v

ibrd v

ibrda v

ibrdf

flname

ibrpp

ibtrap

ibrsc [v]

ibrsp

Conduct a parallel poll

Configure applications monitor

Request/release system control

Return serial poll byte

2,3

(continues)

GPIB-PC User Manual

5-8

Section Five

Table 5.1 - Syntax of GPIB Functions in IBIC (continued)

IBIC

Request service

Change seconday address

Send interface clear

ibrsv v

ibsad v

ibsic

Set/clear remote enable line

Abort asynchronous operation

Change/disable time limit

Configure applications monitor

ibsre [v]

ibstop

ibtmo v

ibtrap

mask v

ibtrg

ibwait

[mask]

ibwrt

stringd

ibwrta

string

ibwrtf

flname

2,3

3,8

Trigger selected device

Wait for selected event

2,8

Write data

Write data asynchronously

Write data to file

NOTES

1. bnameis the symbolic name of the new board, e.g., ibbna

gpib1.

2. Values enclosed in square brackets ([]) are optional. The

default value is 0 for ibwaitand 1 for all other functions.

3. v is a hex, octal, or decimal integer. Hex numbers must be

preceded by zero and x (e.g., 0xD). Octal numbers must be

preceded by zero only (e.g., 015). Other numbers are assumed

to be decimal.

4. stringconsists of a list of ASCII characters, octal or hex

bytes, or special symbols. The entire sequence of characters

must be enclosed in quotes. An octal byte consists of a

backslash character followed by the octal value. For example,

octal 40 would be represented by \40. A hex byte consists of a

backslash character and a character x followed by the hex

value. For example, hex 40 would be represented by \x40.

The two special symbols are \r for a carriage return character

and \n for a linefeed character. These symbols provide a more

convenient method for inserting the carriage return and linefeed

5-9

GPIB-PC User Manual

IBIC

Section Five

characters into the string as shown in the following string:

F3R5T1\r\n. Since the carriage return can be represented

equally well in hex, xDand r are equivalent strings.

5. bdnameis the symbolic name of the new device or board; for

example, ibfind dev1or set gpib0.

6. v is the number of bytes to read.

7. flnameis the DOS pathname of the file to be read or written,

e.g., \test\meteror printr.buf.

8. mask is a hex, octal, or decimal integer (see note 3) or a mask

bit mnemonic.

Status Word

All IBICfunctions return the status word IBSTAin two forms — a hex

value in square brackets, and a list of mnemonics in parentheses.

Example:

dev1: ibwrt "f2t3x"

[900](rqs cmpl)

COUNT: 5

dev1:

In this example, the status word shows that the device level write

operation completed successfully and that dev1 is requesting service.

Table 5.2 lists the mnemonics of the status word. This is the same list

that is given in Table 4.1.

GPIB-PC User Manual

5-10

Section Five

IBIC

Table 5.2 - Status Word Layout

Mnemonics Bit

Hex

Pos.

8000

4000

2000

1000

800

Function Description

Value

Type

GPIB error

Time limit exceeded

ERR

TIMO

END

END or EOS detected

SRQ interrupt received

Device requesting

SRQI

RQS

service

CMPL

LOK

REM

CIC

100

I/O completed

Lockout State

Remote State

Controller-In-Charge

Attention is asserted

Talker

Listener

Device Trigger State

Device Clear State

ATN

TACS

LACS

DTAS

DCAS

Error Code

If a GPIB-PC function completes with an error, IBICalso displays the

error mnemonic. The following example illustrates an error condition

occurred in the data transfer.

Example:

dev1:

ibwrt "f2t3x"

[8100] (err cmpl)

ERROR: ENOL

COUNT: 1

dev1:

In this example, there are no Listeners; perhaps dev1is powered off.

5-11

GPIB-PC User Manual

IBIC

Section Five

Byte Count

When an I/O function completes, IBIC displays the actual number of

bytes sent or received, regardless of the existence of an error condition.

Auxiliary Functions

Table 5.3 summarizes the auxiliary functions that IBIC supports.

Table 5.3 - Auxiliary Functions that IBICSupports

Description

Function

Syntax

set bdname

help

Note

1,2

Select active device or board

Display help information

[option]

Repeat previous function

Turn OFF display

Turn ON display

Execute function n times

Execute previous function n times n* !

Execute indirect file

Display string on screen

n* function

$ filename

string

Exit or quit

Notes

1. bdnameis the symbolic name of the new device or board; for

example, ibfind dev1or set gpib0.

2. Call IBFIND initially to open each device or board.

3. If optionis omitted, a menu of options appears.

4. Replace function with correct IBIC function syntax.

5. filenameis the DOS pathname of a file that contains IBIC

functions to be executed.

GPIB-PC User Manual

5-12

Section Five

6. stringconsists of a list of ASCII characters, octal or hex

IBIC

bytes, or special symbols. The entire sequence of characters

must be enclosed in quotes. An octal byte consists of a

backslash character followed by the octal value. For example,

octal 40 would be represented by 040. A hex byte consists of a

backslash character and a character x followed by the hex

value. For example, hex 40 would be represented by x40. The

two special symbols are \r for a carriage return character and

\nfor a linefeed character. These symbols provide a more

convenient method for inserting the carriage return and linefeed

characters into the string as shown in this string:

"F3R5T1\r\n". Since the carriage return can be represented

equally well in hex, \xDand \r are equivalent strings.

SET(Select Device or Board)

The SET function specifies a previously opened device or board to be

used for subsequent GPIB-PC functions executed from IBIC. SET

eliminates the need to include the BD unit descriptor in each GPIB-PC

function call.

The argument bdname is any of the symbolic device or board names

recognized by the handler. These are the default names gpib0,

gpib1, and dev1through dev16unless the device names have been

changed with IBCONF.

An example of the SET function appeared earlier in this section.

HELP(Display Help Information)

The HELPfunction gives causal information about IBICand its

functions to be displayed on the screen.

5-13

GPIB-PC User Manual

IBIC

Section Five

!(Repeat Previous Function)

The ! function causes the most recent function executed to be repeated.

Example:

Screen Image

gpib0: ibsic

Clear

Comments

Send Interface

[130] ( cmpl

cic atn )

gpib0: !

Repeat ibsic

[130] ( cmpl cic atn )

gpib0: !

Repeat ibsic again

[130] ( cmpl cic atn )

-(Turn OFF Display)

The -function causes the GPIB-PC function output NOT to be

displayed on the screen. This function is useful when you want to

repeat a GPIB-PC I/O function quickly without waiting for screen output

to be displayed.

GPIB-PC User Manual

5-14

Section Five

IBIC

+(Turn ON Display)

The + function causes the display to be restored.

The following example shows how the -and +functions are used.

Twenty-four consecutive letters of the alphabet are read from a device

using three IBRDcalls.

Example:

ibrd 8

dev1:

[4100] (end cmpl)

COUNT: 8

61 62 63 64 65 66 67 68 a b c d

e f g h

dev1: -

dev1: ibrd 8

dev1: +

dev1: ibrd 8

[4100] (end cmpl)

COUNT: 8

71 72 73 74 75 76 77 78 q r s t

u v w x

5-15

GPIB-PC User Manual

IBIC

Section Five

n* (Repeat Function n Times)

The n* function repeats the execution of the specified function n times,

where nis an integer. In the following example, the message Hello

will be sent to the printer five times.

Example:

printer: 5*ibwrt "Hello"

The function name can be replaced with the ! function. Thus, if this

example is done the following way, the word Hellowill be sent 20

more times, then 10 more times.

Example:

printer:

20* !

10* !

Notice that the multiplier (*) does not become part of the function

name; that is, ibwrt "Hello"is repeated 20 times, not 5* ibwrt

"Hello".

GPIB-PC User Manual

5-16

Section Five

IBIC

$(Execute Indirect File)

In the $ function, an indirect file is a text file that contains IBIC

functions. It is similar to a DOS batch file and is created the same way.

This function reads the specified indirect file and executes the IBIC

functions in sequence as if they were entered in that order from the

keyboard.

Example:

gpib0: $ usrfile

executes the IBICfunctions listed in the file usrfile, and

gpib0: 3*$ usrfile

repeats that operation three times.

The display mode, in effect before this function is executed, is restored

afterward but may be changed by functions in the indirect file.

5-17

GPIB-PC User Manual

IBIC

Section Five

PRINT(Display the ASCII String)

The PRINTfunction can be used to echo a string to the screen.

Example:

dev1:

hello

print "hello"

dev1: print "and\r\n\x67\x6f\x6f\x64\x62\x79\x65"

and

goodbye

PRINTcan be used to display comments from indirect files. The print

strings will appear even if the display is suppressed with the - function.

The second PRINTexample illustrates the use of hex values in IBIC

strings.

Eor Q(exit or quit)

The DOS exit command or the IBICfunction Eor Qreturns you to

DOS.

GPIB-PC User Manual

5-18

Section Five

IBIC

IBIC Sample Programs

Refer to Section Four A, BASICA/QuickBASIC GPIB Programming

Examples, for a description of the programming steps that could be used

to program a representative IEEE-488 instrument from your personal

computer using the GPIB-PC handler functions. The applications are

written using IBICcommands.

Device Function Calls

To communicate with a device, first "find" the device name which was

given to the device in the IBCONF program.

Example:

:ibfind dvm

DVM:

Clear the device. The user should check for ERR after each GPIB

function call to be safe.

Example:

DVM:

ibclr

[0100] (cmpl)

5-19

GPIB-PC User Manual

IBIC

Section Five

Write the function, range, and trigger source instructions to the DVM.

Example:

ibwrt "F3R7T3"

DVM:

[0100] (cmpl)

Trigger the device.

Example:

ibtrg

DVM:

[0100] (cmpl)

Wait for the DVM to request service or for a timeout; if the current

timeout limit is too short, use ibtmo to change it.

Example:

DVM: ibwait (TIMO RQS)

[800] (rqs)

GPIB-PC User Manual

5-20

Section Five

IBIC

Read the serial poll status byte. This serial poll status byte will vary

depending on the device used.

Example:

ibrsp

DVM:

[0100] (cmpl)

Poll: 0x40 (decimal : 32)

The read command displays the data on the screen both in hex values

and their ASCII equivalents.

Example:

DVM: ibrd 18

[0100] (cmpl)

4E 44 43 56 20 30 30 30 N D C V

2E 30 30 34 37 45 28 30 . 0 0 4 7

OA OA

0 0 0

E + 0

5-21

GPIB-PC User Manual

IBIC

Section Five

Return to DOS.

Example:

DVM: e

Board Function Calls

Make the interface board the current board.

Example:

:ibfind gpib0

GPIB0:

Send the interface clear message (IFC) to all devices. This clears the

bus and asserts attention (ATN) on the bus. The user should check for

ERR after each GPIB function call to be safe.

Example:

GPIB0: ibsic

[0130] (cmpl cic atn)

GPIB-PC User Manual

5-22

Section Five

IBIC

Turn on the remote enable signal (REN).

Example:

GPIB0: ibsre 1

[0130] (cmpl cic atn)

previous value: 0

Set up the addressing for the device to listen and the computer to talk.

The question mark (?) and underscore (_) characters represent the

unlisten (UNL) and untalk (UNT) commands, respectively. These must

be sent first in every IBCMDfunction to reset the bus addressing. The @

character represents the GPIB-PC board's talk address. This was

calculated using the Multiline Interface Message chart in Appendix A.

The GPIB-PC board is at GPIB primary address 0. Moving across to the

Talk address column, the appropriate ASCII character is an @ character.

In a similar manner the ! character represents the listen address of the

device which in this case is assumed to be at GPIB primary address 1.

The Multiline Interface Command chart indicates that the listen address

for a device at primary address of 1 is an ! character.

Example:

GPIB: ibcmd "?_@!"

[0188] (cmpl lok cic atn tacs)

5-23

GPIB-PC User Manual

IBIC

Section Five

Write the function, range, and trigger source instructions to the DVM.

Be sure an error has not occurred before proceeding with the sample

program.

Example:

GPIB0: ibwrt "F3R7T3"

[01A8] (cmpl lok cic tacs)

Send the group execute trigger message (GET) to trigger a

measurement reading. The GET message is represented by the hex

value 8.

Example:

GPIB0: ibcmd "\x08"

[0188] (cmpl lok cic atn tacs)

Wait for the DVM to set SRQ or for a timeout; if the current timeout

limit is too short, use IBTMOto change it.

Example:

GPIB-PC User Manual

5-24

Section Five

IBIC

GPIB0: ibwait (TIMO SRQI)

[4188] (timo cmpl lok cic atn tacs

)

Set up the device for a serial poll. The ?and _ represent the unlisten

(UNL) and untalk (UNT) characters, respectively, and reset the address.

The hex value 18 represents the serial poll enable function, while the A

represents the device's talk address.

Example:

GPIB: ibcmd "?_\x18A"

Read the status byte. The status byte returned may vary depending on

the device used.

Example:

GPIB0: ibrd 1

[01E4] (cmpl lok rem cic atn lacs)

Complete the serial poll by sending the serial poll disable message

(SPD).

5-25

GPIB-PC User Manual

IBIC

Section Five

Example:

GPIB0: ibcmd "\x19"

[01F4] (cmpl lok rem cic atn lacs)

Since the DVM and the GPIB-PC are still addressed to talk and to

listen, the measurement can be read.

Example:

GPIB0: ibrd 20

[01E4] (cmpl lok rem cic lacs)

0D 0A 4E 44 43 56 2D 30 • • N D C

30 30 2E 30 30 34 37 45 0 0 . 0 0

V - 0

4 7 E

2B 30 0D 0A

+ 0 • •

To close out a programming sequence, send the interface clear message

(IFC) to initialize the bus.

Example:

GPIB: ibsic

[0160} (cmpl lok rem cic)

Return to DOS.

GPIB-PC User Manual

5-26

Section Five

IBIC

Example:

GPIB0:

5-27

GPIB-PC User Manual

Section Six - Applications Monitor

The applications monitor is a memory resident program which is useful

in debugging sequences of GPIB calls from within your application.

The monitor provides the capability to trap on return from GPIB driver

calls, allowing you to inspect function arguments, buffers, return values,

GPIB global variables, and other pertinent data. You may select the

trap so that it occurs on return from every GPIB handler call, returns

only on those calls which return an error indication; or occurs only on

those calls which are returned with particular bit patterns in the GPIB

status word.

While trapped, you will see a popup screen (Figure 6.1) that provides

details of the call being trapped. In addition, you can view a listing of

up to 255 of the preceding calls to verify that the sequence of calls and

their arguments have occurred as intended.

Figure 6.1 - Applications Monitor Popup Screen

6-1

GPIB-PC User Manual

IBIC

Section Six

In many cases, use of the applications monitor allows you to omit

explicit error-checking code from the application. If a program is

expected to run without errors, trapping on errors will cause the monitor

to be invoked only if an error occurs during a GPIB call. You may then

take the action necessary to fix the problem.

Currently, the applications monitor is only supported by the Revision

C.5.1 and later versions of the GPIB Rev. C handler.

Installing the Applications Monitor

The applications monitor is included on the distribution diskette as the

file APPMON.COM. To install it, type the following command in

response to the DOS prompt:

APPMON

If the GPIB handler is not present or the monitor has been previously

installed, it will not load and an error message will be printed.

Once run, the monitor will remain resident in memory until you reboot

the system. Should you later desire that you no longer wish to devote

memory to the resident applications monitor, simply reboot your system;

the monitor will no longer be loaded.

IBTRAP

The applications monitor provides the capability to trap on GPIB

handler calls which have particular bits set in the GPIB status word.

The trap options are set by the special GPIB handler call, IBTRAP.

This call can be made either from the application program, or from the

special utility program called IBTRAP.EXE.

Both the function call and the DOS utility allow you to select a mask,

which determines those functions which will be trapped, and a monitor

mode, which selects what is to be displayed when a call is trapped.

The exact syntax of the function call is dependent on the language you

are using. See the description of IBTRAPin your language section for

details on including IBTRAPcalls in your application.

The utility program IBTRAPmay be used to set the trap mode from

DOS. Simply type IBTRAPin response to the DOS prompt, specifying

GPIB-PC User Manual

6-2

Section Six

IBIC

the desired combination of the flags which are listed on the following

pages.

Select one or more mask flags:

-all all GPIB calls

-err GPIB error

-timo timeout

-end GPIB-PC detected END or EOS

-srqi SRQ on

-rqs device requesting service

-cmpl I/O completed

-lok GPIB-PC is in Lockout State

-rem GPIB-PC is in Remote State

-cic GPIB-PC is Controller-In-Charge

-atn attention is asserted

-tacs GPIB-PC is Talker

-lacs GPIB-PC is Listener

-dtas GPIB-PC is in Device Trigger State

-dcas GPIB-PC is in Device Clear State

6-3

GPIB-PC User Manual

IBIC

Section Six

Select only one monitor flag:

-off turns the monitor off. No recording or trapping occurs.

-rec instructs the monitor to record all GPIB handler calls but

no trapping occurs.

-dis instructs the monitor to record all GPIB handler calls and

display whenever a trap condition exists.

Omitting either the mask or the monitor flags will leave its current

configuration unchanged. Invoking IBTRAPwithout any flags will

display the valid flags and their current state. This has no effect on the

monitor configuration.

By selecting various flags for the mask and monitor parameters, you

may achieve a variety of trapping configurations. The following are

some examples:

IBTRAP-cic -atn -dis record all GPIB handler calls and

display the monitor whenever

attention is asserted or the GPIB-

PC Controller-in-Charge.

IBTRAP-srq -rec

IBTRAP-dis

record all GPIB handler calls and

set the trap mask to trap when SRQ

is on. Do not display the monitor

when a trap condition exists.

record all GPIB handler calls and

display the monitor whenever a trap

condition exists. The trap mask

remains unchanged.

IBTRAP-off

disable the monitor. No recording

or trapping is performed.

See Section Four of the Programming Language Supplement for the

appropriate syntax to use in your application program.

GPIB-PC User Manual

6-4

Section Six

IBIC

Applications Monitor Options

When displayed, the applications monitor allows you to view the

parameters of the current GPIB call, change the display and trap modes,

and scan the GPIB session summary. The monitor displays the

following information pertinent to the current GPIB call:

Device

Function

Value

symbolic device name.

GPIB-PC function mnemonic and description.

for functions that have a number as their second

parameter, this contains its value, otherwise it is

undefined.

Count

for functions that have a count as their third

parameter this contains its value, otherwise it is

undefined.

IBSTA

IBERR

contains the GPIB status information.

contains the GPIB error information, or the

previous value of the value parameter if no error

occurred.

IBCNT

contains the number of bytes transferred.

Buffer

Value

for functions that have a buffer as a parameter, this

displays its contents. Each byte of the buffer is

shown with its index, character image, and ASCII

value.

Status

shows the state of the individual bits of IBSTA. A

"*" indicated the bit is active. The active bits of

the trap mask are highlighted for easy

identification.

Error

shows the state of the individual bits of IBERR. A

"*" indicates the bit is active.

Information contains any message concerning the current GPIB

call.

6-5

GPIB-PC User Manual

IBIC

Section Six

NOTE: All numbers are displayed in hexadecimal. Also, the monitor is

unable to record IBFINDor IBTRAPcalls.

GPIB-PC User Manual

6-6

Section Six

IBIC

Main Commands

When the main monitor screen is displayed, the following command

keys are available:

continue executing applications program

display session summary

configure trap mask

configure monitor mode

hide/show monitor

clear session summary buffer

display command key list

scroll buffer up one character

scroll buffer down one character

scroll buffer up one page

scroll buffer down one page

scroll to beginning of buffer

scroll to end of buffer

F10

Cursor Up

Cursor Down

Page Up

Page Down

Home

End

6-7

GPIB-PC User Manual

IBIC

Section Six

Session Summary Screen

This session summary can be viewed by pressing F2. Once displayed,

the following keys can be used to manipulate the display:

Cursor Up

Cursor Down

Page Up

scrolls summary up one line

scrolls summary down one line

scrolls summary up one page

scrolls summary down one page

scrolls to the top of summary

scrolls to the end of summary

Page Down

Home

End

Escape or F2

exit the session summary display and return to the

main monitor screen

Configuring the Trap Mask

Pressing F5 allows you to change the current configuration of the trap

mask. It yields a popup menu with each of the status bits displayed

along with their current state (either ON or OFF). Use the UP and

DOWN arrow keys to highlight the desired bit and press F1 to toggle its

state. Pressing ENTER will record the changes. Pressing ESCAPE will

cancel this action and leave the mask unchanged. Selecting all bits has

the effect of trapping on every call, while turning them all off causes no

trapping to occur.

Configuring the Monitor Mode

Pressing F6 allows you to change the current configuration of the

monitor mode. It yields a popup menu with the current mode

checkmarked. Use the up and down arrow keys to highlight the new

mode and press ENTER to record the change. Pressing ESCAPE will

cancel this action and leave the mode unchanged.

GPIB-PC User Manual

6-8

Section Six

IBIC

Hiding and Showing the Monitor

Pressing F7 will hide the monitor and restore the contents of the screen.

This allows you to view program output written to the screen while

active within the monitor. Pressing F7 again will restore the monitor.

6-9

GPIB-PC User Manual

Appendix A - Multiline Interface

Messages

The following tables are multiline interface messages (sent and

received with ATN TRUE).

The subsequent pages contain an interface message reference list,

which describes the mnemonics and messages which correspond to the

interface functions.

A-1

GPIB-PC User Manual

Multiline Interface Messages

Appendix A

Hex Oct Dec ASCII Msg

Hex Oct Dec ASCII M s g

000

001

002

003

004

005

006

007

NUL

SOH

STX

ETX

EOT SDC

ENQ PPC

ACK

040 32

041 33

042 34

043 35

044 36

045 37

046 38

047 39

MLA0

MLA1

MLA2

MLA3

MLA4

MLA5

MLA6

MLA7

GTL

BEL

010

011

GET

TCT

050 40

051 41

052 42

053 43

054 44

055 45

056 46

057 47

(

)

MLA8

MLA9

012 10 LF

013 11 VT

014 12 FF

015 13 CR

016 14 SO

017 15 SI

MLA10

MLA11

MLA12

MLA13

MLA14

MLA15

020 16 DLE

021 17 DC1

022 18 DC2

023 19 DC3

024 20 DC4

025 21 NAK PPU

026 22 SYN

027 23 ETB

060 48

061 49

062 50

063 51

064 52

065 53

066 54

067 55

MLA16

MLA17

MLA18

MLA19

MLA20

MLA21

MLA22

MLA23

LLO

DCL

030 24 CAN SPE

070 56

071 57

072 58

073 59

074 60

075 61

076 62

077 63

MLA24

MLA25

MLA26

MLA27

MLA28

MLA29

MLA30

UNL

031 25 E M

032 26 SUB

033 27 ESC

034 28 FS

035 29 GS

036 30 RS

037 31 US

SPD

;

GPIB-PC User Manual

A-2

Appendix A

Multiline Interface Messages

Hex Oct Dec ASCII M s g

100 64

101 65

102 66

103 67

104 68

105 69

106 70

107 71

MTA0

MTA1

MTA2

MTA3

MTA4

MTA5

MTA6

MTA7

140 96

141 97

142 98

143 99

144 100

145 101

146 102

147 103

MSA0,PPE

MSA1,PPE

MSA2,PPE

MSA3,PPE

MSA4,PPE

MSA5,PPE

MSA6,PPE

MSA7,PPE

110 72

111 73

112 74

113 75

114 76

115 77

116 78

117 79

MTA8

MTA9

150 104

151 105

152 106

153 107

154 108

155 109

156 110

157 111

MSA8,PPE

MSA9,PPE

MSA10,PPE

MSA11,PPE

MSA12,PPE

MSA13,PPE

MSA14,PPE

MSA15,PPE

MTA10 6A

MTA11 6B

MTA12 6C

MTA13 6D

MTA14 6E

MTA15 6F

120 80

121 81

122 82

123 83

124 84

125 85

126 86

127 87

MTA16 70

MTA17 71

MTA18 72

MTA19 73

MTA20 74

MTA21 75

MTA22 76

MTA23 77

160 112

161 113

162 114

163 115

164 116

165 117

166 118

167 119

MSA16,PPD

MSA17,PPD

MSA18,PPD

MSA19,PPD

MSA20,PPD

MSA21,PPD

MSA22,PPD

MSA23,PPD

130 88

131 89

132 90

133 91

134 92

135 93

136 94

137 95

[

]

MTA24 78

MTA25 79

MTA26 7A

MTA27 7B

MTA28 7C

MTA29 7D

MTA30 7E

170 120

171 121

172 122

173 123

174 124

175 125

176 126

{

MSA24,PPD

MSA25,PPD

MSA26,PPD

MSA27,PPD

MSA28,PPD

MSA29,PPD

MSA30,PPD

}

UNT

177 127 DEL

A-3

GPIB-PC User Manual

Multiline Interface Messages

Interface Message Reference List

Appendix A

Mnemonic

M e s s a g e

Interface Function(s)

LOCAL MESSAGES RECEIVED (by interface functions)

gts

ist

lon

[lpe]

ltn

go to standby

individual status qualifier

listen only

local poll enable

listen

P P

L, LE

P P

L, LE

lun

local unlisten

L, LE

nba

pon

rdy

rpp

rsc

rsv

rtl

sic

sre

tca

tcs

ton

new byte available

power on

ready

SH, AH, T, TE, L, LE, SR, RL, PP, C

request parallel poll

request system control

request service

return to local

send interface clear

send remote enable

take control asynchronously

take control synchronously

talk only

R L

AH, C

T, TE

REMOTE MESSAGES RECEIVED

ATN

attention

SH, AH, T, TE, L, LE, PP, C

DAB

data byte

(via L, LE)

DAC

data accepted

DAV

data valid

DCL

device clear

END

end

(via L, LE)

GET

GTL

group execute trigger

go to local

R L

IDY

identify

L, LE, PP

IFC

interface clear

T, TE, L, LE, C

LLO

local lockout

R L

MLA

[MLA]

MSA or [MSA]

MTA

[MTA]

OSA

OTA

PCG

PPC

[PPD]

[PPE]

PPRn

PPU

my listen address

my secondary address

my talk address

other secondary address

other talk address

primary command group

parallel poll configure

parallel poll disable

parallel poll enable

parallel poll response n

parallel poll unconfigure

L, LE, RL

TE, LE

T, TE

TE, LE, PP

P P

(via C)

P P

GPIB-PC User Manual

A-4

Appendix A

Multiline Interface Messages

Interface Message Reference List (Continued)

Mnemonic

M e s s a g e

Interface Function(s)

(continued)

REMOTE MESSAGES RECEIVED

REN

RFD

RQS

[SDC]

SPD

SPE

SRQ

STB

TCT or [TCT]

UNL

remote enable

ready for data

request service

selected device clear

serial poll disable

serial poll enable

service request

status byte

R L

(via L, LE)

T, TE

(via C)

(via L, LE)

take control

unlisten

L, LE

REMOTE MESSAGES SENT

ATN

DAB

DAC

DAV

DCL

END

GET

GTL

IDY

attention

data byte

data accepted

data valid

device clear

end (via T)

group execute trigger

go to local

(via C)

identify

IFC

LLO

interface clear

local lockout

(via C)

P P

MLA or [MLA] my listen address

MSA or [MSA] my secondary address

MTA or [MTA] my talk address

OSA

other secondary address

OTA

PCG

PPC

[PPD]

[PPE]

PPRn

PPU

REN

RFD

RQS

[SDC]

SPD

other talk address

primary command group

parallel poll configure

parallel poll disable

parallel poll enable

parallel poll response n

parallel poll unconfigure

remote enable

(via C)

ready for data

request service

selected device clear

serial poll disable

serial poll enable

service request

status byte

T, TE

(via C)

(via T, TE)

(via C)

SPE

SRQ

STB

TCT

UNL

UNT

take control

unlisten

untalk

A-5

GPIB-PC User Manual

Appendix B - Common Errors and

Their Solutions

Some errors occur more frequently than others. These common errors

and their solutions are listed in this appendix, according to the error

code that was returned from the function as indicated by IBERR. A full

explanation of all possible errors is in Section Four. Later in this

appendix are descriptions of error situations that do not return an error

code.

EDVR(0)

Error Condition: DOS error (see IBCNT for DOS error code).

Solutions:

•

Check that GPIB.COM, CONFIG.SYS, and IBCONF.EXEare

in the root directory of your boot drive. (Enter DIR \ from the

boot drive and verify that these files exist).

Check that CONFIG.SYScontains the line

DEVICE=GPIB.COM. (Enter TYPE \CONFIG.SYSfrom the

boot drive and verify that the line exists there).

Reboot your system after you install the software.

ECIC(1)

Error Condition: Function requires GPIB-PC to be Controller-In-

Charge.

Solutions:

•

Run IBCONFand make sure the board being used (GPIB0or

GPIB1) is configured to be the System Controller.

•

If executing board functions, call IBSIC to become Controller-

In-Charge before any other function calls that require that

capability.

•

If control has been passed away with an IBPCTcall, wait for it

to be returned with the IBWAITfunction.

©Natio_Dn_oa_wl_nI_lon_as_dtr_fu_rom_me_Wnt_ws_wC_.So_or_mp_a._nuals.coB_m-_.1_{All Manuals Sea}G_rchP_AIB_nd-P_DC_owU_nls_oe_ar_d.Manual

Common Errors and Their Solutions

Appendix B

ENOL(2)

Error Condition: Write function detected no Listeners.

Solutions:

•

Check that the device is powered on, and also that at least two-

thirds of the devices on the GPIB are turned on.

Inspect the interconnecting cable to see that the devices are

attached and that the connectors are seated properly.

Check the switches or control panel of the device and make

sure its GPIB address is what you think it is. Check also

whether the device uses extended addressing and requires a

primary and secondary address. (Some devices use multiple

secondary addresses to enable different internal functions).

•

For device write functions, run IBCONFfrom the root directory

and check that the device's address (including secondary

address) is correct. If a change is made, reboot the system.

Then run IBICto verify that the address is correct, as follows.

Open the device you want to write to using IBFINDand

execute IBPADand IBSAD calls, passing each the address

value you believe is correct. If secondary addressing is not

used, pass a value of zero to the IBSAD function. Assuming

these calls do NOT return with an error, IBICwill return the

previous address value, which will be the same as the new one

if you have correctly configured the device.

•

For board write functions, make sure the device is addressed

properly using the IBCMDfunction before the write call. Verify

that the low five bits of the listen address (and if appropriate

the secondary address) used in the IBCMD call match the

device's GPIB address(es) and also that the listen address is in

the range 20-3E hex (32-62 decimal) and the secondary address

is in the range 60-7E hex (92-126 decimal).

GPIB-P_DC_owU_nlos_ae_dr _fM_roman_Wu_wal_{w.Somanuals.co}B_m-_.2_{All Manua}©_lsN_Sa_et_ai_ro_cn_ha_Al_nI_dn_Ds_otr_wu_nm_loe_an_d.ts Corp.

Appendix B

Common Errors and Their Solutions

EADR(3)

Error Condition: GPIB-PC (GPIB0or GPIB1) is not addressed

correctly.

Solutions:

•

Use IBCMDto send the appropriate Talk or Listen address

before attempting an IBWRTor IBRD.

•

If calling IBGTS with the shadow handshake feature, call

IBCMDto ensure that the GPIB ATN line is asserted.

EARG(4)

Error Condition: Invalid argument to function call.

Solutions:

•

Errors received from IBIC:

Verify syntax in Section Five.

Make sure the address of the board in IBCONFdoes not

conflict with that of a device.

•

Errors received when running your application program:

Verify syntax in Section Four.

Make sure the address of the board in IBCONFdoes not

conflict with that of a device.

©Natio_Dn_oa_wl_nI_lon_as_dtr_fu_rom_me_Wnt_ws_wC_.So_or_mp_a._nuals.coB_m-_.3_{All Manuals Sea}G_rchP_AIB_nd-P_DC_owU_nls_oe_ar_d.Manual

Common Errors and Their Solutions

Appendix B

ESAC(5)

Error Condition: GPIB-PC not System Controller as required.

Solutions:

•

Run IBCONFand make sure the board (GPIB0or GPIB1) is

configured to be System Controller.

•

Issue a board IBRSCfunction call with a value of 1 to request

System Control.

EABO(6)

Error Condition: I/O operation aborted.

Solutions:

•

Check that the device is powered on.

Verify proper cable connections.

Errors received from IBRD:

Some devices will not send data unless they have received

data telling them what to send. This is caused by devices

having the capability of sending several types of data.

Issue an IBWRTto set up the device, and then an IBRDto

receive the information.

If you have not changed any of the default EOS or EOI

settings in IBCONF, the reads will terminate when the

buffer is full or when EOI is set. If your device sends an

EOS terminating character such as a carriage return rather

than EOI, then use IBCONF to change the device

characteristics. Remember to reboot after leaving IBCONF

if you made any changes.

GPIB-P_DC_owU_nlos_ae_dr _fM_roman_Wu_wal_{w.Somanuals.co}B_m-_.4_{All Manua}©_lsN_Sa_et_ai_ro_cn_ha_Al_nI_dn_Ds_otr_wu_nm_loe_an_d.ts Corp.

Appendix B

Common Errors and Their Solutions

ENEB(7)

Error Condition: Non-existent GPIB-PC board.

Solution:

•

Run IBCONFand make sure the board type (GPIB-PCII, PCIIA

or PCIII) and base I/O address match the hardware and address

switch settings. If you make any changes, reboot after leaving

IBCONF.

EOIP(10)

Error Conditions: I/O started before previous operation completed.

Solution:

•

When using asynchronous reads or writes, call IBWAITto wait

for CMPL status before making another call.

ECAP(11)

Error Condition: No capability for operation.

Solution:

•

Run IBCONFand verify that the capability to do a particular

call is enabled (e.g., you must be System Controller to execute

the IBSREfunction). Check both device and board

capabilities. Reboot after leaving IBCONFif you made any

changes.

EFSO(12)

Error Condition: File system error.

Solutions:

•

Check the disk files to make sure names are properly specified

and that the file exists.

•

If more room is needed on the disk, delete some files.

Rename any files which have the same name given to a device

in IBCONF, or rename the device.

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Common Errors and Their Solutions

Appendix B

EBUS(14)

Error Condition: Command error during device call.

Solutions:

•

Find out which device is abnormally slow to accept commands

and fix the problem with the device.

•

If more time is needed to send commands, lengthen the time

limit of the board in IBCONFor with IBTMO.

ESTB(15)

Error Condition: Serial poll status byte(s) lost.

Solutions:

•

Call IBRSPmore often to read the status bytes.

Ignore ESTB.

ESRQ(16)

Error Condition: SRQ stuck in the ON position.

Solutions:

•

Ignore ESRQ until all devices are found. It occurred because

the device asserting SRQ was not opened with IBFIND. The

automatic serial polling polls only the opened devices.

Check that you have used IBFIND to open all devices on the

GPIB that could assert SRQ. Remove any device from the bus

if it is not being accessed.

•

Using IBIC, attach one device at a time and determine that it

is unasserting SRQ after being polled.

Inspect the interconnecting cable to see that the devices are

attached and that the connectors are seated properly.

GPIB-P_DC_owU_nlos_ae_dr _fM_roman_Wu_wal_{w.Somanuals.co}B_m-_.6_{All Manua}©_lsN_Sa_et_ai_ro_cn_ha_Al_nI_dn_Ds_otr_wu_nm_loe_an_d.ts Corp.

Appendix B

Common Errors and Their Solutions

Other Error Conditions

Listed below are general errors which may occur when using the GPIB-

PC hardware and software.

Error Condition: Attempts to run the GPIB utility programs, IBDIAG,

IBTEST, or IBICand returns Bad command or File Nameerror

from DOS. Also, the distribution files do not appear to be on the boot

disk after running IBSTART.

Solution:

• IBSTARTcopies the files to the subdirectory \GPIB-PCon the

boot disk. Only GPIB.COMand IBCONF.EXEare copied to

the root directory. Change to the \GPIB-PCdirectory with the

DOS command cd \GPIB-PCto run other programs.

Error Condition: Function call does not return and the program seems

to hang forever.

Solutions:

•

Run IBCONFand confirm that the board's DMA channel and

interrupt line match the hardware settings. Then run IBTEST

after rebooting. Also check that the DMA channel and interrupt

line do not conflict with other devices in the computer.

•

Check that the time limit is not set to zero, which results in

infinite time limits. To do this, run IBCONFand look at the

time limit value both for your device and your board. Or, from

IBIC, call IBTMO and pass to it the timeout argument value

you believe is correct (the default is 13, which represents 10

seconds). Assuming that the IBTMOcall does not result in an

error, the previous value returned by the call will equal the

value passed to it if the time limit was what you expected.

•

Check that you do not call IBWAITfor an event that may not

happen without also waiting for TIMO as well. For example, if

you fail to set the TIMO bit while waiting for RQS from a

device, and for some reason the device will not assert SRQ, the

IBWAITcall will not return.

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Common Errors and Their Solutions

Appendix B

•

All device functions require the board to be Controller-In-

Charge. If it is not, either because it is not System Controller

or because it has passed control away, the function will not

return until control is passed back to the board. If this never

happens, the function will never return. To check the board's

System Controller status, either run IBCONFand verify that the

board is configured to be System Controller, or run IBICand

execute the function IBRSCwith an argument of 1. The

previous value is reported as 1 if the board was System

Controller before your function call. To check that the board

has not passed control, confirm that you never call IBPCT, nor

IBCMD with the Take Control command (9 hex) as an

argument.

Error Condition: The computer crashes.

Solutions:

•

Run IBCONFand confirm that the board's DMA channel and

interrupt line match the hardware settings. Also check that the

DMA channel and interrupt line do not conflict with other

devices in the computer.

•

Configure the hardware and software to not use DMA and/or

interrupts. You may have a PC compatible that is not totally

compatible.

Check that none of your device names is the same as any of

your file or directory names, not including the file or directory

name suffix.

Error Condition: IBDIAGreports a DMA or interrupt problem.

Solutions:

•

Reconfigure the hardware and software for another DMA

channel and/or interrupt line. You might have a conflict with

another device.

With the GPIB-PCIIA and GPIB-PCIII, which have shareable

interrupt capability, check that another device on the same line

really has the shareable interrupt capability. Many do not.

If an interrupt problem persists, configure the hardware and

software for non-DMA or non-interrupt operation. You may

have a PC compatible that is not totally compatible.

GPIB-P_DC_owU_nlos_ae_dr _fM_roman_Wu_wal_{w.Somanuals.co}B_m-_.8_{All Manua}©_lsN_Sa_et_ai_ro_cn_ha_Al_nI_dn_Ds_otr_wu_nm_loe_an_d.ts Corp.

Appendix B

Common Errors and Their Solutions

Error Condition: IBICreports an error on IBFINDor IBFINDreturns

a negative unit descriptor.

Solutions:

•

Check the solutions listed for EDVR, ENEB, or EARG error

codes.

•

Run IBCONFfrom the root directory to check that the device or

board name is correct.

Error Condition: The GPIB device being programmed appears to

accept the instruction but does not behave properly.

Solutions:

•

Check that the instruction sent with the write function contains

the proper delimiters and message termination characters. For

example, some devices require a carriage return and/or a

linefeed character before they will execute the instruction.

Other devices require special characters to separate multiple

instruction messages. Your instruction manual may be

incomplete or ambiguous, so try several possible combinations.

•

When running a program check for errors after each GPIB-PC

function call . If an early call failed but you did not check

IBSTA, later functions will behave improperly and give

misleading status data.

Check that the board you are using and the GPIB device you

are programming are not at the same GPIB address. If using

device functions, run IBCONFto do this.

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Appendix C - Differences Between

Software Revisions

This appendix describes differences between current revisions of the

software.

Revision B and Revision C

Interrupts

In Rev. C, the software is interrupt driven, improving its performance

and taking advantage of the interrupt capabilities of the GPIB-PC

interface board.

Startup Program

The Rev. C standard software package includes a startup program

(IBSTART.BAT) to get you started faster. Among other things, this

program creates or modifies your CONFIG.SYSfile (IBCONFused to

do this).

Configuration Program

In Rev. C, the configuration program, IBCONF.EXE, is streamlined and

is easier to use. It no longer modifies CONFIG.SYS, since the start-up

program now does this. The Automatic Serial Poll and Lockout features

are now configurable at the board level.

Interface Bus Interactive Control Program (IBIC)

In Rev. C, IBIC.EXEincludes a help feature. Also, you now call

IBFINDas you would in your application program. It must be called at

the beginning of IBIC.EXE to enable a device or board, and be called

subsequently to enable any previously unreferenced device or board.

C-1

GPIB-PC User Manual

Differences Between Software Revisions

Appendix C

New Functions

File I/O functions have been added to the handler, allowing data to be

read into or written from a file. In Interpretive BASIC, integer I/O

functions have been added to allow the data to be stored in integer

arrays instead of character strings.

Modified Functions

IBFINDno longer uses up available DOS file descriptors, so the Too

Many Fileserror will not occur as a result of too many open boards

and devices. IBONL, when called with a 0, no longer invalidates the

unit descriptor. It still disables the board or device, however.

Language Interfaces

If you customized a language interface for a compiler not supported in

Rev. B, it will need to be modified to work with Rev. C. This is

because Rev. C language interfaces use a new, faster method of

entering the handler.

General

The Rev. C software package as a whole has been modified to allow it

to run with a variety of GPIB-PC cards and systems.

Revision C and Revision D

Both Rev. C and Rev. D software are current and are actively supported.

The one you receive depends on the GPIB-PC interface hardware you

buy.

Device Functions

Device I/O functions do not unaddress devices at the end of the call.

Also, the functions do not address devices known to be already

addressed from the previous call. This significantly improves through-

put on multiple reads from or multiple writes to the same device.

Also in Rev. D, if the access board is not CIC when a device call is

made, the ECIC error is returned.

Non-Interrupt Mode

Rev. D has no non-interrupt mode. You must select interrupt level 2-7.

GPIB-PC User Manual

C-2

Appendix C

Differences Between Software Revisions

Asynchronous I/O

There is no asynchronous capability on Rev. D. If you call an

asynchronous function (IBRDA, IBRDIA, IBWRTA, IBWRTIA,

IBCMDA, and IBSTOP) the ECAP error is returned immediately.

DMA on the GPIB-PCIII

The GPIB-PCIII board has additional DMA capability. If you have the

GPIB-PCIII, consult the READ.MEfile of the accompanying Distribution

Diskette for details.

Local Lockout

In Rev. D there is no automatic local lockout configuration setting.

Therefore, Rev. D does not place devices in lockout.

SRQI Status Bit

In Rev. D the SRQI status bit always reflects the current level of the

SRQ line whether or not the GPIB-PC is CIC.

ATN and/or TIMO

With the IBWAITfunction, it is not possible to wait for the ATN or

TIMO conditions. If no other conditions exist, the function returns

immediately.

DCAS and DTAS Status Bits

In Rev. D, these bits are cleared at the beginning of a new function call.

Thus, if the application program must be sensitive to the messages

Device Clear, Selected Device Clear, or Group Executive Trigger, the

status bits must be checked after each function call.

Printer Support

Rev. C has printer support and Rev. D does not.

C-3

GPIB-PC User Manual

Appendix D - Using your Printer with

the GPIB-PC

The Serial/Parallel port redirection feature in the GPIB-PC software

allows you to replace default printer drivers so that output can be

redirected to a GPIB printer or plotter. After the appropriate

configuration, these GPIB devices can be accessed through system calls

and other language printer commands (e.g., LPRINT, LPRINT USING,

PRINT#, LLIST, COPY, and PRINT).

Installation

When installing the GPIB-PC software, run an interactive program

IBCONF which allows you to change predefined device names and

addresses. Your software internally calls a DOS device driver which

corresponds to the port where it expects to find the printer. If you

define, in IBCONF, the device name your software expects, this should

"fool" DOS and send the data to the GPIB device. The following

examples demonstrate the use of parallel port redirection (LPT1) but

could also be used for serial port redirection (COM1).

PRN, LPT2, LPT3

To install the software follow these steps:

•

Run IBSTARTas explained in Section Two.

Run IBCONFand follow all instructions.

In IBCONF, define dev1:

Change the name dev1to LPT1;

Change the primary address to the GPIB address of your

printer.

•

Exit IBCONF.

Reboot the system.

Run IBTESTto verify correct software installation.

D-1

GPIB-PC User Manual

Using your Printer with the GPIB-PC

Appendix D

Examples:

System

PRINT FILE

COPY FILE LPT1

BASIC

10 LPRINT "hello"

10 OPEN "LPT1" FOR OUTPUT AS #1

20 PRINT #1, "it works!"

GPIB-PC User Manual

D-2

Appendix E - Application Notes

Application Note 1 - Computer to Computer Data

Transfer

A common application in the laboratory is the transfer of data between

two computers. The GPIB performs this function quite readily. The

following discussion illustrates the data transfer between two computers

called master and slave.

Step 1. Configure the Computers

Configure one computer as system controller and the second as a device

or non-system controller. On the master computer, run the IBCONF

program, rename DEV1to SLAVE, ensure the primary address is set to

1, and set 'Board Is System-Controller' to YES. On the second

computer, run the IBCONFprogram, set 'Board Is System-Controller to

NO and set the primary address of GPIB0to 1. Exit the IBCONF

programs and reboot both computers.

Step 2. Establish Communication

Run the IBIC facility on both computers, type the respective

commands, and press the enter key.

Example:

Master

Slave

: ibfind GPIB0

ibfind SLAVE

E-1

GPIB-PC User Manual

Application Notes

Appendix E

Each computer finds the appropriate device and should respond as

follows:

Example:

Master

Slave

SLAVE:

GPIB0:

Step 3. Transfer Data

In this example, you must press RETURN on the slave before you press

RETURN on the master.

Example:

Master

Slave

SLAVE: ibwrt "hello"

GPIB0: ibrd 5

The master sends a data string to the slave, which should appear as

follows:

Master

Slave

[0100](cmpl)

Count: 5

"hello"

Count: 5

NOTE: The read and write commands must be executed here within a

certain time limit of each other; otherwise the timeout factor which

comes at a default of ten seconds will abort the operation.

GPIB-PC User Manual

E-2

Appendix F

Customer Communication

National Instruments provides comprehensive technical assistance around

the world. In the U.S. and Canada, applications engineers are available

Monday through Friday from 8:00 a.m. to 6:00 p.m. (central time). In other

countries, contact the nearest branch office. You may fax questions to us at

any time.

Corporate Headquarters

(512) 795-8248

Technical support fax:

(800) 328-2203

(512) 794-5678

Branch Offices

Australia

Austria

Belgium

Denmark

Finland

France

Germany

Italy

Phone Number

(03) 879 9422

(0662) 435986

02/757.00.20

45 76 26 00

(90) 527 2321

(1) 48 14 24 00

089/741 31 30

02/48301892

(03) 3788-1921

03480-33466

32-848400

Fax Number

(03) 879 9179

(0662) 437010-19

02/757.03.11

45 76 71 11

(90) 502 2930

(1) 48 14 24 14

089/714 60 35

02/48301915

(03) 3788-1923

03480-30673

32-848600

Japan

Netherlands

Norway

Spain

Sweden

Switzerland

U.K.

(91) 640 0085

08-730 49 70

056/20 51 51

0635 523545

(91) 640 0533

08-730 43 70

056/20 51 55

0635 523154

F-1

GPIB-PC User Manual

Documentation Comment Form

National Instruments encourages you to comment on the documentation

supplied with our products. This information helps us provide quality

products to meet your needs.

Title: GPIB-PC User Manual for the IBM Personal Computer and

Compatibles

Edition Date: April 1988

Part Number: 320014-01

Please comment on the completeness, clarity, and organization of the

manual.

(continues)

If you find errors in the manual, please record the page numbers and

describe the errors.

Thank you for your help.

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Mail to:

Technical Publications

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Fax to:

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(512) 794-5678

Glossary

ACCEPTOR HANDSHAKE - A GPIB interface function that receives

data or commands. Listeners use this function to receive data, and

all devices use it to receive commands. See Source Handshake and

Handshake.

ACCESS BOARD - The GPIB-PC board that controls and

communicates with the devices on the bus that are attached to it.

APPLICATIONS MONITOR - A resident program that is useful in

debugging sequences of GPIB calls from within your application.

APPMON.COM - The file on the distribution diskette which contains the

applications monitor.

ATTENTION or ATN - A GPIB line that distinguishes between

commands and data messages. When ATN is asserted, bytes on the

GPIB DIO lines are commands.

AUTOMATIC SERIAL POLLING - A feature of the GPIB-PC software

in which serial polls are executed automatically by the handler

whenever a device asserts the GPIB SRQ line.

BD - A variable name and first argument of each function call that

contains the unit descriptor of the GPIB-PC interface board or other

GPIB device that is the object of the function. See Unit Descriptor.

BOARD - One of the GPIB-PC interface boards in the computer. See

Device.

BOARD FUNCTION - A function that operates on or otherwise pertains

to one of the GPIB-PC interface boards in the computer. These

boards are referred to as GPIB0, GPIB1, etc. See Device Function.

BOOT - To load the operating system programs from floppy or hard disk

into memory and to begin executing the code. A hard boot is when

power is applied to the computer. A warm or soft boot is when

specific keys are pressed, such as CTRL SHIFT DEL on the IBM

PC.

BOOT DRIVE - The floppy or hard disk drive that is used to boot the

computer.

G-1

GPIB-PC User Manual

Glossary

COMMAND or COMMAND MESSAGE - Common term for interface

message.

CONFIG.SYS - The DOS file that contains the names of the loadable

device driver or handler programs that DOS loads when it is booted.

CONFIGURATION - The process of altering the software parameters in

the handler that describe the key characteristics of the devices and

boards that are manipulated by the handler. By keeping this

information, such as GPIB address, in the handler, it does not have

to be defined in each application program. IBCONF.EXE is the

GPIB-PC configuration program.

CONTROLLER or CONTROLLER-IN-CHARGE (CIC) - The device that

manages the GPIB by sending interface messages to other devices.

DATA or DATA MESSAGE - Common term for device dependent

message.

DAV or DATA VALID - One of the three GPIB handshake lines. See

Handshake.

DCL or DEVICE CLEAR - A GPIB command used to reset the device or

internal functions of all devices. See IFC and SDC.

DECLARATION FILE - A GPIB-PC file that contains code that must be

placed at the beginning of an application program to allow it to

properly access the handler. DECL.BAS is the Declaration File for

programs written in Interpretive BASICA. See Language Interface.

DEVICE - An instrument, peripheral, computer, or other electronics

equipment that can be programmed over the GPIB. See Board.

DEVICE DEPENDENT MESSAGE - A message sent from one device to

another device, such as a programming instructions, data, or device

status. See Commands or Interface Message.

DEVICE FUNCTION - A function that operates on or otherwise pertains

to a GPIB device rather than to the GPIB-PC interface board in the

computer. See Board Function.

DIO1-DIO8 - The GPIB lines that are used to transmit command or data

bytes from one device to another.

GPIB-PC User Manual

G-2

Glossary

DMA or DIRECT MEMORY ACCESS - High speed data transfer

between the GPIB-PC and memory that is not handled directly by

the CPU. Not available on some systems. See Programmed I/O.

DRIVER - Common term for software used to manipulate a device or

interface board. See Handler.

END or END MESSAGE - A message that signals the end of a data

string. END is sent by asserting the GPIB End or Identify (EOI) line

with the last data byte.

EOI - A GPIB line that is used to signal either the last byte of a data

message (END) or the parallel poll Identify (IDY) message.

EOS or EOS BYTE - A 7- or 8-bit end-of-string character that is sent as

the last byte of a data message.

GET or GROUP EXECUTE TRIGGER - A GPIB command to trigger a

device or internal function of an addressed Listener.

GPIB or GENERAL PURPOSE INTERFACE BUS - The common name

for the communications interface system defined in IEEE Std 488.

Hewlett-Packard, the inventor of the bus, calls it the HP-IB.

GPIB ADDRESS - The address of a device on the GPIB, composed of a

primary address (MLA and MTA) and perhaps a secondary address

(MSA). The GPIB-PC has both a GPIB address and an I/O address.

GPIB.COM - The GPIB-PC handler filename.

GPIB-PC - The name for the National Instruments family of GPIB

interface boards to personal computers. Family members include

GPIB-PCII, GPIB-PCIIA,GPIB-PCIII, GPIB-PCjr, GPIB-PC2000,

and Rainbow GPIB-PC.

GTL or GO TO LOCAL - A GPIB command used to place an addressed

Listener in local (front panel) control mode.

HANDSHAKE - The mechanism used to transfer bytes from the Source

Handshake function of one device to the Acceptor Handshake

function of another device. The three GPIB lines DAV, NRFD, and

NDAC are used in an interlocked fashion to signal the phases of the

transfer, so that bytes can be sent asynchronously (e.g, without a

clock) at the speed of the slowest device.

G-3

GPIB-PC User Manual

Glossary

HANDLER - Device driver software installed within the operating

system. Same as a DOS installed device driver. See Driver.

HARD BOOT - See Boot.

HIGH-LEVEL FUNCTION - A device function that combines several

rudimentary board operations into one function so that the user does

not have to be concerned with bus management or other GPIB

protocol matters. See Low-Level Function.

IBCONF.EXE - The GPIB-PC configuration program. See Configuration.

IBCNT - A global variable that is updated after each I/O function call to

show the actual number of bytes sent or received.

IBERR - A global variable that contains the specific error code

associated with a function call that failed.

IBSTA - A global variable that is updated at the end of each function

call with important status information such as the occurrence of an

error.

IBSTART.BAT - The GPIB-PC installation program.

IBTEST.BAT - The GPIB-PC diagnostic program.

IFC or INTERFACE CLEAR - A GPIB line used by the System

Controller to initialize the bus. See DCL and SDC.

INTERFACE MESSAGE - A broadcast message sent from the Controller

to all devices and used to manage the GPIB. Common interface

messages include Interface Clear, listen addresses, talk addresses,

and Serial Poll Enable/Disable. See Data or Device Dependent

Message.

I/O or INPUT/OUTPUT - In the context of this manual, the transmission

of commands or messages between the computer via the GPIB-PC

and other devices on the GPIB.

I/O ADDRESS - The address of the GPIB-PC from the CPU's point of

view, as opposed to the GPIB address of the GPIB-PC. Also called

port address or board address.

LAD or LISTEN ADDRESS - See MLA.

GPIB-PC User Manual

G-4

Glossary

LANGUAGE INTERFACE - Code that enables an application program

written in a particular language to call handler functions. BIB.M is

the language interface for Interpretive BASIC.

LISTENER - A GPIB device that receives data messages from a Talker.

LLO or LOCAL LOCKOUT - A GPIB command used to tell all devices

that they may or should ignore remote (GPIB) data messages or

local (front panel) controls, depending on whether the device is in

local or remote program mode.

LOW-LEVEL FUNCTION - A rudimentary board or device function that

performs a single operation. See High-Level Function.

MLA or MY LISTEN ADDRESS - A GPIB command used to address a

device to be a Listener. There are 31 of these primary addresses.

MTA or MY TALK ADDRESS - A GPIB command used to address a

device to be a Talker. There are 31 of these primary addresses.

MSA or MY SECONDARY ADDRESS - A GPIB command used to

address a device to be a Listener or a Talker when extended (two

byte) addressing is used. The complete address is a MLA or MTA

address followed by an MSA address. There are 31 of these

secondary addresses for a total of 961 distinct listen or talk

addresses for devices.

NDAC or NOT DATA ACCEPTED - One of the three GPIB handshake

lines. See Handshake.

NRFD or NOT READY FOR DATA - One of the three GPIB handshake

lines. See Handshake.

ON PEN STATEMENT - National Instruments uses this statement to

intercept SRQ interrupts and make them available to user programs.

OPENED DEVICE OR BOARD - One that has been enabled or placed

online by the IBFIND function.

PARALLEL POLL - The process of polling all configured devices at

once and reading a composite poll response. See Serial Poll.

PORT ADDRESS - See I/O Address.

G-5

GPIB-PC User Manual

Glossary

PPC or PARALLEL POLL CONFIGURE - A GPIB command used to

configure an addressed Listener to participate in polls.

PPD or PARALLEL POLL DISABLE - A GPIB command used to

disable a configured device from participating in polls. There are

16 PPD commands.

PPE or PARALLEL POLL ENABLE - A GPIB command used to enable

a configured device to participate in polls and to assign a DIO

response line. There are 16 PPE commands.

PPU or PARALLEL POLL UNCONFIGURE - A GPIB command used to

disable any device from participating in polls.

PROGRAMMED I/O - Low speed data transfer between the GPIB-PC

and memory in which the CPU moves each data byte according to

program instructions. See DMA.

REN or REMOTE ENABLE - A GPIB line controlled by the System

Controller but used by the CIC to place devices in remote program

mode.

ROOT DIRECTORY - The top level directory on a floppy or hard disk.

SDC or SELECTED DEVICE CLEAR - A GPIB command used to reset

internal or device functions of an addressed Listener. See DCL and

IFC.

SERIAL POLL - The process of polling and reading the status byte of

one device at a time. See Parallel Poll.

SOFT BOOT - See Boot.

SOURCE HANDSHAKE - The GPIB interface function that transmits

data and commands. Talkers use this function to send data and the

Controller uses it to send commands. See Acceptor Handshake and

Handshake.

SPD or SERIAL POLL DISABLE - A GPIB command that cancels a

SPE command.

SPE or SERIAL POLL ENABLE - A GPIB command used to enable a

specific device to be polled. That device must also be addressed to

talk. See SPD.

GPIB-PC User Manual

G-6

Glossary

SRQ or SERVICE REQUEST - The GPIB line that a device asserts to

notify the CIC that the device needs servicing.

STATUS BYTE - The data byte sent by a device when it is serially

polled.

STATUS WORD - Same as IBSTA.

SYSTEM CONTROLLER - The single designated controller that can

assert control (become CIC of the GPIB) by sending the Interface

Clear (IFC) message. Other devices can become CIC only by

having control passed to them.

T1 - A GPIB timing parameter primarily associated with the data

settling time, i.e., the time in which new bytes on the DIO lines are

allowed to settle before the DAV signal is asserted. T1 ranges from

350 nsec to above 2 µsec.

TAD or TALK ADDRESS - See MTA.

TALKER - A GPIB device that sends data messages to Listeners.

TCT or TAKE CONTROL - A GPIB command used to pass control of

the bus from the current Controller to an addressed Talker.

TIMEOUT - A feature of the GPIB-PC handler that prevents I/O

functions from hanging indefinitely when there is a problem on the

GPIB.

TLC - An integrated circuit that implements most of the GPIB Talker,

Listener, and Controller functions in hardware.

UNIT DESCRIPTOR - A number that is used by the handler to

temporarily identify a device or board that has been opened with the

IBFIND function. The descriptor is not related to the unit's GPIB

address.

UNL or UNLISTEN - A GPIB command that unaddresses any active

Listeners.

UNT or UNTALK - A GPIB command that unaddresses an active Talker.

WARM BOOT - See Boot.

G-7

GPIB-PC User Manual

Index

! (repeat previous function) 5-14

$ (execute indirect file) 5-17

+ (turn ON display) 5-15

- (turn OFF display) 5-14

Applications Monitor 6-1

APPMON.COM 2-2

IBTRAP 6-2

IBTRAP.EXE 2-2

Installation 6-2

Main Commands 6-6

Options 6-5

Session Summary 6-7

Auto serial polling (Boards Only), disable 2-15

Automatic serial polling 4-13

Auxiliary IBIC functions 5-12

Base I/O address (Boards Only) 2-15

BASICA

Files 4A-2

GPIB-PC I/O Functions 4A-5

ON SRQ 4A-6

Programming Preparation 4A-3

Board

base I/O address 2-15

characteristics 2-12

DMA Channel 2-16

functions, purpose of 3-9, 3-14

Internal Clock Frequency 2-16

Primary GPIB Address 2-12

Secondary GPIB Address 2-12

Timeout Settings 2-12

Boot

from floppy disk 2-3

from hard disk 2-3

Byte count 5-12

I-1GPIB-PC User Manual

Index

Calling Syntax 3-1

Characteristics

device/board 2-11

each GPIB 2-7

electrical GPIB 1-5

instruments 2-7

physical GPIB 1-5

Clearing

device 3-4

the GPIB 3-4

Concepts and terms, device map 2-11

Configuration

requirements 1-9

linear 1-7

star 1-8

Configurations, default 2-8

Controller-In-Charge 1-2,

Count variable 4-11

Data lines 1-3

Data transfer termination method 4A-26

Default characteristics, functions that alter 2-17

Default configurations 2-8

Primary 2-8

Device

characteristics 2-12

clearing 3-4

function calls 4-12

functions 3-14

Primary GPIB Address 2-12

Secondary GPIB Address 2-12

Timeout Settings 2-12

Device map for board GPIBx, upper level 2-10

Device map, concepts and terms 2-11

Device/board characteristics, lower level 2-11

Differences between software revisions C-1

Disable auto serial polling (Boards Only) 2-15

DMA channel (Boards Only) 2-16

GPIB-PC User Manual

I-2

Index

Electrical characteristics 1-5

EOI w/last byte of write, setting 2-14

EOS

byte 2-14

modes 2-14

Error codes 4-6, 5-11

Errors and Solutions B-1

Execute Indirect File ($) 5-17

Exiting IBCONF 2-16

Floppy disk, boot 2-3

Functions and syntax, IBIC 5-7

Functions

that alter default characteristics 2-17

auxiliary 5-12

MC-GPIB 5-7

high level 3-1

low level 3-1

General programming information 4-1

Glossary F-1

GPIB

address, primary 2-12

address, secondary 2-12

characteristics

electrical 1-5

physical 1-5

clearing 3-4

configuration requirements 1-9

connector and the signal assignment 1-6

data lines 1-3

error codes 4-6

functions 5-7

messages 1-1

operation 1-1

data lines 1-3

handshake lines 1-3

interface management lines 1-4

signals and lines 1-3,