National Instruments NI 9235 User manual

OPERATING INSTRUCTIONS AND SPECIFICATIONS
NI 9235/9236
8-Channel, 24-Bit Quarter-Bridge Analog Input
Module
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NI 9235/9236 2ni.com
This document describes how to use the National Instruments 9235
and National Instruments 9236 and includes specifications and
terminal assignments. In this document, the NI 9235 and NI 9236
are referred to inclusively as the NI 9235/9236. 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 9235/9236. 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. 3NI 9235/9236
Safety Guidelines
Operate the NI 9235/9236 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 9235/9236 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 9235/9236 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 9235/9236 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 9235/9236 in Gas Group IIC
hazardous locations or in ambient temperatures of
–40 °C ≤Ta ≤70 °C, youmust 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. 5NI 9235/9236
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 9235/9236 6ni.com
Connecting the NI 9235/9236
The NI 9235/9236 has a 24-terminal detachable spring-terminal
connector that provides connections for 8 analog input channels.
Figure 1. NI 9235/9236 Terminal Assignments
EXC0
AI0
RC0
EXC2
AI2
RC2
EXC4
AI4
RC4
EXC6
AI6
RC6
EXC1
AI1
RC1
EXC3
AI3
RC3
EXC5
AI5
RC5
EXC7
AI7
RC7
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24

© National Instruments Corp. 7NI 9235/9236
Yo ucan connect a quarter-bridge sensor to each channel. Each
channel has an EXC terminal that provides the excitation voltage
stimulus, an AI terminal that measures the bridge voltage, and an
RC terminal that provides the quarter-bridge completion. Refer to
Figure 2 for an illustration of how to connect quarter-bridge
sensors to the NI 9235/9236.
Figure 2. Quarter-Bridge Connections for the NI 9235/9236
*For best system accuracy, set up the connections to EXC and RC with
equal lengths of an identical wire type and gauge.
** For best system accuracy, set up the connection to AI directly at the
sensor instead of shorting AI to RC directly at the terminals.
EXC*
AI**
RC*NI 9235/9236

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Connecting Wires to the NI 9235/9236 Connector
Use a flathead screwdriver with a blade smaller than 2.3 × 1.0 mm
(0.09 × 0.04 in.) to connect wires to the detachable spring-terminal
connector. Insert the screwdriver into a spring clamp activation slot
and press a wire into the corresponding connector terminal, then
remove the screwdriver to clamp the wire into the terminal. Refer
to the Specifications section for more information about
spring-terminal wiring.
Figure 3. Connecting Wires to the NI 9235/9236 Connector

© National Instruments Corp. 9NI 9235/9236
Wiring for High-Vibration Applications
If an application is subject to high vibration, National Instruments
recommends that youuse the NI 9965 backshell kit to protect the
connections. Refer to Figure 4 for an illustration of the NI 9965
connector backshell.
Figure 4. NI 9965 Connector Backshell

NI 9235/9236 10 ni.com
NI 9235/9236 Circuitry
The NI 9235/9236 is isolated from earth ground. However, the
individual channels are not isolated from each other. The EXC
terminals all connect internally to a common excitation supply.
Yo umust connect each EXC terminal to only one gage to maintain
the channel-to-channel crosstalk performance of the module.
Each channel on the NI 9235/9236 has an independent 24-bit ADC
and input amplifier that enables youto sample signals from all
eight channels simultaneously. Refer to Figures 5 and 6 for
illustrations of the input circuitry for one channel of the
NI 9235/9236.