OPERATING INSTRUCTIONS AND SPECIFICATIONS
NI 9234
4-Channel, 5 V, 24-Bit Software-Selectable
IEPE and AC/DC Analog Input Module
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Safety Guidelines
Operate the NI 9234 only as described in these operating
instructions.
Hot Surface This icon denotes that the component may be
hot. Touching this component may result in bodily injury.
Safety Guidelines for Hazardous Locations
The NI 9234 is suitable for use in Class I, Division 2, Groups A, B,
C, D, T4 hazardous locations; Class I, Zone 2, AEx nA IIC T4, and
Ex nA IIC T4 hazardous locations; and nonhazardous locations
only. Follow these guidelines if you are installing the NI 9234 in a
potentially explosive environment. Not following these guidelines
may result in serious injury or death.
Caution Do not disconnect I/O-side wires or connectors
unless power has been switched off or the area is known
to be nonhazardous.
Caution Do not remove modules unless power has been
switched off or the area is known to be nonhazardous.
© National Instruments Corp.
3
NI 9234 Operating Instructions and Specifications
Caution Substitution of components may impair
suitability for Class I, Division 2.
Caution For Zone 2 applications, install the system
in an enclosure rated to at least IP 54 as defined by
IEC 60529 and EN 60529.
Caution For Zone 2 applications, connected signals must
be within the following limit:
Capacitance..........................0.2 μF max
Special Conditions for Hazardous Locations Use in Europe
This equipment has been evaluated as Ex nA IIC T4 equipment
under DEMKO Certificate No. 07 ATEX 0626664X. Each module
is marked
II 3G and is suitable for use in Zone 2 hazardous
locations. If you are using the NI 9234 in Gas Group IIC hazardous
locations or in ambient temperatures of –40 °C ≤ Ta ≤ 70 °C, you
must use the device in an NI chassis that has been evaluated as
EEx nC IIC T4, Ex nA IIC T4, or Ex nL IIC T4 equipment.
NI 9234 Operating Instructions and Specifications
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Special Conditions for Marine Applications
Some modules are Lloyd’s Register (LR) Type Approved for
marine applications. To verify Lloyd’s Register certification, visit
ni.com/certification and search for the LR certificate, or
look for the Lloyd’s Register mark on the module.
Caution To meet radio frequency emission requirements
for marine applications, use shielded cables and install
the system in a metal enclosure. Suppression ferrites
must be installed on power supply inputs near power
entries to modules and controllers. Power supply and
module cables must be separated on opposite sides of the
enclosure and must enter and exit through opposing
enclosure walls.
© National Instruments Corp.
5
NI 9234 Operating Instructions and Specifications
Connecting the NI 9234
The NI 9234 has four BNC connectors that provide connections to
four simultaneously sampled analog input channels.
AI0+
AI0–
AI1+
AI1–
AI2+
AI2–
AI3+
AI3–
Figure 1. NI 9234 Connector Assignments
NI 9234 Operating Instructions and Specifications
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Each channel has a BNC connector to which you can connect
a signal source. You can also enable excitation current on a
per-channel basis to connect Integrated Electronics Piezoelectric
(IEPE) sensors. Refer to the NI 9234 Circuitry section for more
information. The center pin of the connector, AI+, provides the DC
excitation, when enabled, and the positive input signal connection.
The shell of the connector, AI–, provides the excitation return path
and the signal ground reference.
Connecting Signal Sources to the NI 9234
You can connect ground-referenced or floating signal sources to
the NI 9234. To avoid picking up ground noise, use a floating
connection. To further minimize ground noise, prevent the metal
shells of the BNC connectors from coming in contact with each
other, the modules, or the chassis.
If you make a ground-referenced connection between the signal
source and the NI 9234, make sure the voltage on the AI– shell
is in the common-mode range to ensure proper operation of the
NI 9234. The AI– shell is protected against accidental contact with
overvoltages within the overvoltage protection range. Refer to the
Specifications section for more information about operating
voltages and overvoltage protection.
© National Instruments Corp.
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NI 9234 Operating Instructions and Specifications
Refer to Figures 2 and 3 for illustrations of connecting grounded
and floating signal sources to the NI 9234.
Signal
Source
AI+
AI–
+
–
NI 9234
Common
Mode
Voltage
Figure 2. Connecting a Grounded Signal Source to the NI 9234
NI 9234 Operating Instructions and Specifications
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Signal
Source
AI+
AI–
+
–
NI 9234
Figure 3. Connecting a Floating Signal Source to the NI 9234
The NI 9234 can also provide an IEPE excitation current for each
channel to measure ground-referenced or floating IEPE sensors.
Typical IEPE sensors have a case that is electrically isolated from
the IEPE electronics, so connecting the sensor to the NI 9234
results in a floating connection even though the case of the sensor
is grounded.
© National Instruments Corp.
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NI 9234 Operating Instructions and Specifications
NI 9234 Circuitry
The NI 9234 analog input channels are referenced to chassis
ground through a 50 Ω resistor. To minimize ground noise, make
sure the chassis ground is connected to earth ground. Each channel
is protected from overvoltages. The input signal on each channel is
buffered, conditioned, and then sampled by a 24-bit Delta-Sigma
ADC. You can configure each channel in software for AC or DC
coupling. For channels set to AC coupling, you can turn the IEPE
excitation current on or off. Refer to the software help for
information about configuring channels on the NI 9234.
NI 9234 Operating Instructions and Specifications 10
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2 mA IEPE on/off
AC/DC Coupling
AI+
AI–
+
–
ADC
Current
Limiting
Diodes
50 Ω
Common
Mode
Bias
Amplifier
and
Prefilter
Current
NI 9234
Figure 4. NI 9234 Input Circuitry for One Channel
The NI 9234 uses common-mode bias current to bias the
current-limiting diodes when IEPE current is turned off. When the
NI 9234 is using grounded signal sources, this current causes an
error that is dependent on the AI– lead impedance. This error is
approximately 50 ppm of range and 15 ppm of reading per Ω of
AI– impedance. The common-mode bias current causes an error
only with grounded sources and is not an issue with floating signal
sources. For best accuracy, use a floating connection or use
low-impedance leads when connecting grounded signal sources.
© National Instruments Corp.
11 NI 9234 Operating Instructions and Specifications
Signal
Source
AI+
AI–
+
–
Common
Mode
Bias
AI– Lead
Impedance
Current
NI 9234
Figure 5. Measurement Error Introduced by Common-Mode Bias Current
The NI 9234 also has TEDS circuitry. For more information about
TEDS, go to ni.com/info and enter rdteds.
NI 9234 Operating Instructions and Specifications 12
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Understanding NI 9234 Filtering
The NI 9234 uses a combination of analog and digital filtering
to provide an accurate representation of in-band signals while
rejecting out-of-band signals. The filters discriminate between
signals based on the frequency range, or bandwidth, of the signal.
The three important bandwidths to consider are the passband, the
stopband, and the alias-free bandwidth.
The NI 9234 represents signals within the passband, as quantified
primarily by passband flatness and phase nonlinearity. All signals
that appear in the alias-free bandwidth are either unaliased signals
or signals that have been filtered by at least the amount of the
stopband rejection.
Passband
The signals within the passband have frequency-dependent gain or
attenuation. The small amount of variation in gain with respect to
frequency is called the passband flatness. The digital filters of the
NI 9234 adjust the frequency range of the passband to match the
data rate. Therefore, the amount of gain or attenuation at a given
frequency depends on the data rate. Figure 6 shows typical
passband flatness for the NI 9234.
© National Instruments Corp.
13 NI 9234 Operating Instructions and Specifications
0.025
0.000
–0.025
–0.050
0
0.1
0.2
0.3
0.4
0.5
Frequency/Data Rate
Figure 6. NI 9234 Typical Passband Flatness
NI 9234 Operating Instructions and Specifications 14
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Stopband
The filter significantly attenuates all signals above the stopband
frequency. The primary goal of the filter is to prevent aliasing.
Therefore, the stopband frequency scales precisely with the data
rate. The stopband rejection is the minimum amount of attenuation
applied by the filter to all signals with frequencies within the
stopband.
Alias-Free Bandwidth
Any signal that appears in the alias-free bandwidth of the NI 9234
is not an aliased artifact of signals at a higher frequency. The
alias-free bandwidth is defined by the ability of the filter to reject
frequencies above the stopband frequency, and it is equal to the
data rate minus the stopband frequency.
© National Instruments Corp.
15 NI 9234 Operating Instructions and Specifications
Understanding NI 9234 Data Rates
The frequency of a master timebase (fM) controls the data rate (fs)
of the NI 9234. The NI 9234 includes an internal master timebase
with a frequency of 13.1072 MHz, but the module also can accept
an external master timebase or export its own master timebase. To
synchronize the data rate of an NI 9234 with other modules that use
master timebases to control sampling, all of the modules must
share a single master timebase source. Refer to the software help
for information about configuring the master timebase source for
the NI 9234. Visit ni.com/info and enter cseriesdoc for
information about C Series documentation.
The following equation provides the available data rates of the
NI 9234:
f
÷ 256
n
--M------------------
fs =
where n is any integer from 1 to 31.
However, the data rate must remain within the appropriate data rate
range. Refer to the Specifications section for more information
about the data rate range. When using the internal master timebase
NI 9234 Operating Instructions and Specifications 16
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of 13.1072 MHz, the result is data rates of 51.2 kS/s, 25.6 kS/s,
17.067 kS/s, and so on down to 1.652 kS/s, depending on the value
of n. When using an external timebase with a frequency other than
13.1072 MHz, the NI 9234 has a different set of data rates.
Note The cRIO-9151 R Series Expansion chassis does
not support sharing timebases between modules.
Sleep Mode
This module supports a low-power sleep mode. Support for sleep
mode at the system level depends on the chassis that the module is
plugged into. Refer to the chassis manual for information about
support for sleep mode. If the chassis supports sleep mode, refer to
the software help for information about enabling sleep mode. Visit
ni.com/info and enter cseriesdoc for information about
C Series documentation.
Typically, when a system is in sleep mode, you cannot
communicate with the modules. In sleep mode, the system
consumes minimal power and may dissipate less heat than it does
in normal mode. Refer to the Specifications section for more
information about power consumption and thermal dissipation.
© National Instruments Corp.
17 NI 9234 Operating Instructions and Specifications
Specifications
The following specifications are typical for the range –40 to 70 °C
unless otherwise noted.
Input Characteristics
Number of channels..........................4 analog input channels
ADC resolution.................................24 bits
Type of ADC.....................................Delta-Sigma
(with analog prefiltering)
Sampling mode.................................Simultaneous
Type of TEDS supported ..................IEEE 1451.4 TEDS Class I
Internal master timebase (fM)
Frequency...................................13.1072 MHz
Accuracy..................................... 50 ppm max
Data rate range (fs) using internal master timebase
Minimum....................................1.652 kS/s
Maximum ...................................51.2 kS/s
NI 9234 Operating Instructions and Specifications 18
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Data rate range (fs) using external master timebase
Minimum....................................0.391 kS/s
Maximum ...................................52.734 kS/s
f
÷ 256
n
--M------------------
1
Data rates (fs)...................................
, n = 1, 2, …, 31
Input coupling...................................AC/DC (software-selectable)
AC cutoff frequency
–3 dB ..........................................0.5 Hz
–0.1 dB.......................................4.6 Hz max
1
The data rate must remain within the appropriate data rate range. Refer to the
Understanding NI 9234 Data Rates section for more information.
© National Instruments Corp.
19 NI 9234 Operating Instructions and Specifications
AC cutoff frequency response
0.5
0.0
–0.5
–1.0
0
1
2
3
4
5
6
7
8
9
10
Frequency (Hz)
NI 9234 Operating Instructions and Specifications 20
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Input range........................................ 5 V
AC voltage full-scale range
Minimum.................................... 5 Vpk
Typical........................................ 5.1 Vpk
Maximum ................................... 5.2 Vpk
Common-mode voltage range
(AI– to earth ground)........................ 2 V max
IEPE excitation current (software-selectable on/off)
Minimum....................................2.0 mA
Typical........................................2.1 mA
Power-on glitch.................................90 μA for 10 μs
© National Instruments Corp.
21 NI 9234 Operating Instructions and Specifications
IEPE compliance voltage..................19 V max
If you are using an IEPE sensor, use the following equation to make
sure your configuration meets the IEPE compliance voltage range.
(Vcommon-mode + Vbias Vfull-scale) must be 0 to 19
where Vcommon-mode is the common-mode voltage applied
to the NI 9234
Vbias is the bias voltage of the IEPE sensor
Vfull-scale is the full-scale voltage of the IEPE sensor
Overvoltage protection (with respect to chassis ground)
For a signal source connected
to AI+ and AI– ........................... 30 V
For a low-impedance source
connected to AI+ and AI–..........–6 to 30 V
Input delay ........................................38.4/ fs + 3.2 μs
NI 9234 Operating Instructions and Specifications 22
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Accuracy1
Percent of
Range*
(Offset Error)
Percent of
Reading
(Gain Error)
Measurement Conditions
Calibrated max (–40 to 70 °C)
Calibrated typ (25 °C 5 °C)
Uncalibrated max (–40 to 70 °C)
Uncalibrated typ (25 °C 5 °C)
* Range = 5.1 Vpk
0.34%,
0.03 dB
0.14%,
7.1 mV
0.05%,
0.005 dB
0.006%,
0.3 mV
1.9%,
0.16 dB
0.27%,
13.9 mV
0.48%,
0.04 dB
0.04%,
2.3 mV
1
Refer to the NI 9234 Circuitry section for information regarding grounded signal
sources and measurement accuracy.
© National Instruments Corp.
23 NI 9234 Operating Instructions and Specifications
Gain drift
Typical........................................0.14 mdB/°C (16 ppm/°C)
Maximum ...................................0.45 mdB/°C (52 ppm/°C)
Offset drift
Typical........................................19.2 μV/°C
Maximum ...................................118 μV/°C
Channel-to-channel matching
Gain
Typical..................................0.01 dB
Maximum.............................0.04 dB
Phase ( fin in kHz) .......................fin · 0.045° + 0.04 max
Passband
Frequency...................................0.45 · fs
Flatness (fs = 51.2 kS/s).............. 40 mdB (pk-to-pk max)
Phase nonlinearity
(fs = 51.2 kS/s) .................................. 0.45° max
Stopband
Frequency...................................0.55 · fs
Rejection.....................................100 dB
NI 9234 Operating Instructions and Specifications 24
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Alias-free bandwidth ........................0.45 · fs
Oversample rate................................64 · fs
Crosstalk (1 kHz)..............................–110 dB
CMRR (fin ≤ 1 kHz)
Minimum....................................40 dB
Typical........................................47 dB
SFDR (fin = 1 kHz, –60 dBFS).........120 dB
Idle channel noise and noise density
Idle Channel
51.2 kS/s
97 dBFS
25.6 kS/s
99 dBFS
2.048 kS/s
103 dBFS
25 μVrms
Noise
50 μVrms
40 μVrms
Noise density
310 nV/√Hz
350 nV/√Hz
780 nV/√Hz
Input impedance
Differential .................................305 kΩ
AI– (shield) to chassis ground....50 Ω
© National Instruments Corp.
25 NI 9234 Operating Instructions and Specifications
Total harmonic distortion (THD)
Input
Amplitude
1 kHz
8 kHz
–87 dB
–80 dB
–1 dBFS
–95 dB
–95 dB
–20 dBFS
Intermodulation distortion (–1 dBFS)
DIN 250 Hz/8 kHz
4:1 amplitude ratio .....................–80 dB
CCIF 11 kHz/12 kHz
1:1 amplitude ratio .....................–93 dB
MTBF ...............................................390,362 hours at 25 °C;
Bellcore Issue 2, Method 1,
Case 3, Limited Part Stress
Method
Note Contact NI for Bellcore MTBF specifications
at other temperatures or for MIL-HDBK-217F
specifications.
NI 9234 Operating Instructions and Specifications 26
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Power Requirements
Power consumption from chassis
Active mode ...............................900 mW max
Sleep mode .................................25 μW max
Thermal dissipation (at 70 °C)
Active mode ...............................930 mW max
Sleep mode .................................25 μW max
Physical Characteristics
If you need to clean the module, wipe it with a dry towel.
Weight...............................................173 g (6.1 oz)
© National Instruments Corp.
27 NI 9234 Operating Instructions and Specifications
Safety
Safety Voltages
Connect only voltages that are within the following limits.
Channel-to-earth ground................... 30 V max,
Measurement Category I
Isolation
Channel-to-channel ....................None
Channel-to-earth ground ............None
Measurement Category I is for measurements performed on
circuits not directly connected to the electrical distribution system
referred to as MAINS voltage. MAINS is a hazardous live electrical
supply system that powers equipment. This category is for
measurements of voltages from specially protected secondary
circuits. Such voltage measurements include signal levels, special
equipment, limited-energy parts of equipment, circuits powered by
regulated low-voltage sources, and electronics.
Caution Do not connect the NI 9234 to signals or use for
measurements within Measurement Categories II, III,
or IV.
NI 9234 Operating Instructions and Specifications 28
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Hazardous Locations
U.S. (UL) ..........................................Class I, Division 2,
Groups A, B, C, D, T4;
Class I, Zone 2,
AEx nA IIC T4
Canada (C-UL) .................................Class I, Division 2,
Groups A, B, C, D, T4;
Class I, Zone 2,
Ex nA IIC T4
Europe (DEMKO).............................Ex nA IIC T4
Safety Standards
This product is designed to meet the requirements of the following
standards of safety for electrical equipment for measurement,
control, and laboratory use:
•
•
IEC 61010-1, EN 61010-1
UL 61010-1, CSA 61010-1
Note For UL and other safety certifications, refer to the
product label or the Online Product Certification section.
© National Instruments Corp.
29 NI 9234 Operating Instructions and Specifications
Electromagnetic Compatibility
This product meets the requirements of the following EMC
standards for electrical equipment for measurement, control,
and laboratory use:
•
•
•
•
•
EN 61326 (IEC 61326): Class A emissions; Basic immunity
EN 55011 (CISPR 11): Group 1, Class A emissions
AS/NZS CISPR 11: Group 1, Class A emissions
FCC 47 CFR Part 15B: Class A emissions
ICES-001: Class A emissions
Note For the standards applied to assess the EMC of this
product, refer to the Online Product Certification section.
Note For EMC compliance, operate this device with
shielded cabling.
NI 9234 Operating Instructions and Specifications 30
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CE Compliance
This product meets the essential requirements of applicable
European Directives as follows:
•
•
2006/95/EC; Low-Voltage Directive (safety)
2004/108/EC; Electromagnetic Compatibility Directive
(EMC)
Online Product Certification
Refer to the product Declaration of Conformity (DoC) for
additional regulatory compliance information. To obtain product
certifications and the DoC for this product, visit ni.com/
certification, search by module number or product line,
and click the appropriate link in the Certification column.
© National Instruments Corp.
31 NI 9234 Operating Instructions and Specifications
Shock and Vibration
To meet these specifications, you must panel mount the system.
Operating vibration
Random (IEC 60068-2-64).........5 grms, 10 to 500 Hz
Sinusoidal (IEC 60068-2-6) .......5 g, 10 to 500 Hz
Operating shock
(IEC 60068-2-27)..............................30 g, 11 ms half sine,
50 g, 3 ms half sine,
18 shocks at 6 orientations
Environmental
National Instruments C Series modules are intended for indoor use
only but may be used outdoors if installed in a suitable enclosure.
Refer to the manual for the chassis you are using for more
information about meeting these specifications.
Operating temperature
(IEC 60068-2-1, IEC 60068-2-2) .....–40 to 70 °C
Storage temperature
(IEC 60068-2-1, IEC 60068-2-2) .....–40 to 85 °C
Ingress protection..............................IP 40
NI 9234 Operating Instructions and Specifications 32
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Operating humidity
(IEC 60068-2-56)..............................10 to 90% RH,
noncondensing
Storage humidity
(IEC 60068-2-56)..............................5 to 95% RH,
noncondensing
Maximum altitude.............................2,000 m
Pollution Degree (IEC 60664)..........2
Environmental Management
NI is committed to designing and manufacturing products in an
environmentally responsible manner. NI recognizes that
eliminating certain hazardous substances from our products is
beneficial to the environment and to NI customers.
For additional environmental information, refer to the NI and the
Environment Web page at ni.com/environment. This page
contains the environmental regulations and directives with which
NI complies, as well as other environmental information not
included in this document.
© National Instruments Corp.
33 NI 9234 Operating Instructions and Specifications
Waste Electrical and Electronic Equipment (WEEE)
EU Customers At the end of their life cycle, all products
must be sent to a WEEE recycling center. For more
information about WEEE recycling centers and National
Instruments WEEE initiatives, visit ni.com/
environment/weee.htm.
˅
RoHS
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Ёᅶ᠋
National Instruments
DŽ݇Ѣ
(RoHS)
Ё
ড়㾘ᗻֵᙃˈ䇋ⱏᔩ
RoHS
National Instruments
ni.com/environment/rohs_chinaDŽ
about China RoHS compliance, go to
environment/rohs_china
(For information
ni.com/
.)
Calibration
You can obtain the calibration certificate and information about
calibration services for the NI 9234 at ni.com/calibration.
Calibration interval ...........................1 year
NI 9234 Operating Instructions and Specifications 34
ni.com
Where to Go for Support
The National Instruments Web site is your complete resource for
technical support. At ni.com/support you have access to
everything from troubleshooting and application development
self-help resources to email and phone assistance from
NI Application Engineers.
National Instruments corporate headquarters is located at
11500 North Mopac Expressway, Austin, Texas, 78759-3504.
National Instruments also has offices located around the world to
help address your support needs. For telephone support in the
United States, create your service request at ni.com/support
and follow the calling instructions or dial 512 795 8248. For
telephone support outside the United States, contact your local
branch office:
Australia 1800 300 800, Austria 43 662 457990-0,
Belgium 32 (0) 2 757 0020, Brazil 55 11 3262 3599,
Canada 800 433 3488, China 86 21 5050 9800,
Czech Republic 420 224 235 774, Denmark 45 45 76 26 00,
Finland 358 (0) 9 725 72511, France 01 57 66 24 24,
Germany 49 89 7413130, India 91 80 41190000,
Israel 972 3 6393737, Italy 39 02 41309277, Japan 0120-527196,
© National Instruments Corp.
35 NI 9234 Operating Instructions and Specifications
Korea 82 02 3451 3400, Lebanon 961 (0) 1 33 28 28,
Malaysia 1800 887710, Mexico 01 800 010 0793,
Netherlands 31 (0) 348 433 466, New Zealand 0800 553 322,
Norway 47 (0) 66 90 76 60, Poland 48 22 3390150,
Portugal 351 210 311 210, Russia 7 495 783 6851,
Singapore 1800 226 5886, Slovenia 386 3 425 42 00,
South Africa 27 0 11 805 8197, Spain 34 91 640 0085,
Sweden 46 (0) 8 587 895 00, Switzerland 41 56 2005151,
Taiwan 886 02 2377 2222, Thailand 662 278 6777,
Turkey 90 212 279 3031, United Kingdom 44 (0) 1635 523545
National Instruments, NI, ni.com, and LabVIEW are trademarks of National Instruments Corporation. Refer to the
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product and company names mentioned herein are trademarks or trade names of their respective companies.
For patents covering National Instruments products/technology, refer to the appropriate location: Help»Patents in
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