National Instruments NI 9234 User manual

NI-9234 Getting
Started
2022-07-06

Contents
Before You Begin. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Safety Guidelines. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Safety Voltages. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Safety Guidelines for Hazardous Locations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Electromagnetic Compatibility Guidelines. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Special Conditions for Marine Applications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Preparing the Environment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Connecting the NI 9234. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Signal Descriptions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Connecting Floating Dierential Signals. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Connecting Grounded Dierential Signals. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Common-Mode Bias Current. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
IEPE Excitation Current. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Overvoltage Protection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Where to Go Next. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
NI Services. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
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NI-9234 Getting Started

Before You Begin
Read the NI-9234 Safety, Environmental, and Regulatory Information and
complete the soware and hardware installation procedures in your chassis
documentation.
Safety Guidelines
Caution Observe all instructions and cautions in the user documentation.
Using the product in a manner not specified can damage the product and
compromise the built-in safety protection.
Attention Suivez toutes les instructions et respectez toutes les mises
en garde de la documentation d'utilisation. L'utilisation du produit de
toute autre façon que celle spécifiée risque de l'endommager et de
compromettre la protection de sécurité intégrée.
Safety Voltages
Connect only voltages that are within the following limits:
Channel-to-earth ground ±30 V maximum, Measurement Category I
Isolation
Channel-to-channel None
Channel-to-earth ground None
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 Gc and Ex nA IIC T4 Gc hazardous locations;
and nonhazardous locations only. Follow these guidelines if you are installing the
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NI-9234 Getting Started

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 o or the area is known to be nonhazardous.
Caution Do not remove modules unless power has been switched o or
the area is known to be nonhazardous.
Caution Substitution of components may impair suitability for Class I,
Division 2, or Zone 2.
Caution The system must be installed in an enclosure certified for the
intended hazardous (classified) location, having a tool secured cover/door,
where a minimum protection of at least IP54 is provided.
Caution For Division 2 and Zone 2 applications, connected signals must
be within the following limits.
Capacitance 0.2 µF maximum
Special Conditions for Hazardous Locations Use in Europe and
Internationally
The NI-9234 has been evaluated as Ex nA IIC T4 Gc equipment under
DEMKO 07ATEX 0626664X and is IECEx UL 14.0089X certified. Each NI-9234 is marked
II 3G and is suitable for use in Zone 2 hazardous locations, in ambient
temperatures of -40 °C ≤ Ta ≤ 70 °C . If you are using the NI-9234 in Gas Group IIC
hazardous locations, you must use the device in an NI chassis that has been
evaluated as Ex nC IIC T4, Ex IIC T4, Ex nA IIC T4, or Ex nL IIC T4 equipment.
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NI-9234 Getting Started

Caution Transient protection shall be provided that is set at a level not
exceeding 140% of the peak rated voltage value of 85 V at the supply
terminals to the equipment.
Caution The system shall only be used in an area of not more than
Pollution Degree 2, as defined in IEC/EN 60664-1.
Caution The system shall be mounted in an ATEX/IECEx-certified
enclosure with a minimum ingress protection rating of at least IP54 as
defined in IEC/EN 60079-15.
Caution The enclosure must have a door or cover accessible only by the
use of a tool.
Electromagnetic Compatibility Guidelines
This product was tested and complies with the regulatory requirements and limits
for electromagnetic compatibility (EMC) stated in the product specifications. These
requirements and limits provide reasonable protection against harmful interference
when the product is operated in the intended operational electromagnetic
environment.
This product is intended for use in industrial locations. However, harmful
interference may occur in some installations, when the product is connected to a
peripheral device or test object, or if the product is used in residential or
commercial areas. To minimize interference with radio and television reception and
prevent unacceptable performance degradation, install and use this product in strict
accordance with the instructions in the product documentation.
Furthermore, any changes or modifications to the product not expressly approved
by National Instruments could void your authority to operate it under your local
regulatory rules.
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NI-9234 Getting Started

Special Conditions for Marine Applications
Some products are approved for marine (shipboard) applications. To verify marine
approval certification for a product, visit ni.com/product-certifications, search by
model number, and click the appropriate link.
Notice In order to meet the EMC requirements for marine applications,
install the product in a shielded enclosure with shielded and/or filtered
power and input/output ports. In addition, take precautions when
designing, selecting, and installing measurement probes and cables to
ensure that the desired EMC performance is attained.
Preparing the Environment
Ensure that the environment in which you are using the NI-9234 meets the following
specifications.
Operating temperature (IEC 60068-2-1, IEC 60068-2-2) -40 °C to 70 °C
Operating humidity (IEC 60068-2-30) 10% RH to 90% RH, noncondensing
Pollution Degree 2
Maximum altitude 5,000 m
Indoor use only.
Note Refer to the NI-9234 Specifications on ni.com/manuals for
complete specifications.
Connecting the NI 9234
The NI 9234 provides connections to four simultaneously sampled analog input
channels.
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NI-9234 Getting Started

Figure 1. NI 9234 Pinout
AI3+
AI3–
AI2+
AI2–
AI0+
AI0–
AI1+
AI1–
Tip To minimize ground noise, prevent the metal shells of the BNC
connectors from coming in contact with each other, the modules, or the
chassis.
Signal Descriptions
Signal Signal Description
AI+ Provides DC excitation (when enabled) and positive input signal connection
AI- Provides excitation return path and signal ground reference
Table 1. Signal Descriptions
Connecting Floating Dierential Signals
You can connect floating dierential signals to the NI-9234.
Figure 2. Connecting Floating Dierential Signals to the NI-9234
NI 9234
AI+
AI–
+
–
Signal
Source
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NI-9234 Getting Started

Connecting Grounded Dierential Signals
You can connect grounded dierential signals to the NI-9234.
Figure 3. Connecting Grounded Dierential Signals to the NI-9234
NI 9234
AI+
AI–
+
–
Signal
Source
Common
Voltage
Mode
Related concepts
■Overvoltage Protection
Common-Mode Bias Current
The NI 9234 uses common-mode bias current to bias the current-limiting diodes
when IEPE current is turned o. 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 ohm 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 low-impedance
leads when connecting grounded signal sources.
Figure 4. Measurement Error Introduced by Common-Mode Bias Current
NI 9234
AI+
AI–
+
–
Signal
Source
AI– Lead
Impedance
Common
Mode
Bias
Current
IEPE Excitation Current
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.
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NI-9234 Getting Started

You can enable excitation current on a per-channel basis. Refer to your soware
help for more information about excitation current.
Overvoltage Protection
The NI-9234 provides overvoltage protection for each channel.
Note Refer to the NI-9234 Specifications on ni.com/manuals for more
information about overvoltage protection.
Where to Go Next
NI Services
Visit ni.com/support to find support resources including documentation,
downloads, and troubleshooting and application development self-help such as
tutorials and examples.
Visit ni.com/services to learn about NI service oerings such as calibration options,
repair, and replacement.
Visit ni.com/register to register your NI product. Product registration facilitates
technical support and ensures that you receive important information updates from
NI.
NI corporate headquarters is located at 11500 N Mopac Expwy, Austin, TX,
78759-3504, USA.
© National Instruments 9
NI-9234 Getting Started
© 2022 National Instruments Corporation.