National Instruments NI 9234 User manual

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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NI 9234 Operating Instructions and Specifications 2ni.com
This document describes how to use the National Instruments 9234
and includes specifications and connector assignments for the
NI 9234. Visit ni.com/info and enter rdsoftwareversion to
determine which software youneed for the modules youare using.
For information about installing, configuring, and programming
the system, refer to the system documentation. Visit ni.com/info
and enter cseriesdoc for information about C Series
documentation.
Note The safety guidelines and specifications in this
document are specific to the NI 9234. The other
components in the system might not meet the same safety
ratings and specifications. Refer to the documentation for
each component in the system to determine the safety
ratings and specifications for the entire system. Visit
ni.com/info and enter cseriesdoc for information
about C Series documentation.

© National Instruments Corp. 3 NI 9234 Operating Instructions and Specifications
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 youare 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.

NI 9234 Operating Instructions and Specifications 4ni.com
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 youare 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.

© National Instruments Corp. 5 NI 9234 Operating Instructions and Specifications
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.

NI 9234 Operating Instructions and Specifications 6ni.com
Connecting the NI 9234
The NI 9234 has four BNC connectors that provide connections to
four simultaneously sampled analog input channels.
Figure 1. NI 9234 Connector Assignments
AI3+
AI3–
AI2+
AI2–
AI0+
AI0–
AI1+
AI1–

© National Instruments Corp. 7 NI 9234 Operating Instructions and Specifications
Each channel has a BNC connector to which youcan connect
a signal source. Youcan 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
Yo ucan 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 youmake 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.

NI 9234 Operating Instructions and Specifications 8ni.com
Refer to Figures 2 and 3 for illustrations of connecting grounded
and floating signal sources to the NI 9234.
Figure 2. Connecting a Grounded Signal Source to the NI 9234
NI 9234
AI+
AI–
+
–
Signal
Source
Common
Mode
Voltage

© National Instruments Corp. 9 NI 9234 Operating Instructions and Specifications
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.
NI 9234
AI+
AI–
+
–
Signal
Source

NI 9234 Operating Instructions and Specifications 10 ni.com
NI 9234 Circuitry
The NI 9234 analog input channels are referenced to chassis
ground through a 50 Ωresistor. 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. Youcan configure each channel in software for AC or DC
coupling. For channels set to AC coupling, youcan turn the IEPE
excitation current on or off. Refer to the software help for
information about configuring channels on the NI 9234.