GETTING STARTED GUIDE
NI 9235
8 AI, ±29.4 mV/V, 24 Bit, 10 kS/s/ch
Simultaneous, 120 Ω Quarter-Bridge Completion
This document explains how to connect to the NI 9235.
Note Before you begin, complete the software and
hardware installation procedures in your chassis
documentation.
Note The guidelines in this document are specific to
the NI 9235. The other components in the system might
not meet the same safety ratings. Refer to the
documentation for each component in the system to
determine the safety and EMC ratings for the entire
system.
Safety Guidelines
Operate the NI 9235 only as described in this document.
Caution Do not operate the NI 9235 in a manner not
specified in this document. Product misuse can result in
a hazard. You can compromise the safety protection
built into the product if the product is damaged in any
way. If the product is damaged, return it to NI for
repair.
2 | ni.com | NI 9235 Getting Started Guide
Safety Voltages
Connect only voltages that are within the following limits:
Between any two terminals ±30 V maximum
Isolation
Channel-to-channel None
Channel-to-earth ground
Continuous 60 VDC,
Measurement Catergory I
Withstand 1,000 Vrms, verified by a 5 s
dielectric withstand test
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.
NI 9235 Getting Started Guide | © National Instruments | 3
Caution Do not connect the NI 9235 to signals or use
for measurements within Measurement Categories II,
III, or IV.
Safety Guidelines for Hazardous Locations
The NI 9235 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 9235 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.
Caution Substitution of components may impair
suitability for Class I, Division 2.
4 | ni.com | NI 9235 Getting Started Guide
Caution For Division 2 and Zone 2 applications,
install the system in an enclosure rated to at least IP54
as defined by IEC/EN 60079-15.
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 9235 has been evaluated as Ex nA IIC T4 Gc equipment
under DEMKO Certificate No. 07 ATEX 0626664X and is
IECEx UL 14.0089X certified. Each NI 9235 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 9235
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.
Caution You must make sure that transient
disturbances do not exceed 140% of the rated voltage.
NI 9235 Getting Started Guide | © National Instruments | 5
Caution The system shall only be used in an area of
not more than Pollution Degree 2, as defined in
IEC 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
6 | ni.com | NI 9235 Getting Started Guide
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.
Special Conditions for Marine Applications
Some products are Lloyd’s Register (LR) Type Approved for
marine (shipboard) applications. To verify Lloyd’s Register
certification for a product, visit ni.com/certification and search
for the LR certificate, or look for the Lloyd’s Register mark on
the product.
Caution 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.
NI 9235 Getting Started Guide | © National Instruments | 7
Preparing the Environment
Ensure that the environment in which you are using the NI 9235
meets the following specifications.
Operating temperature
(IEC 60068-2-1, IEC 60068-2-2)
-40 °C to 70 °C
Operating humidity
(IEC 60068-2-78)
10% RH to 90% RH,
noncondensing
Pollution Degree 2
Maximum altitude 5,000 m
Indoor use only.
Note Refer to the device datasheet on ni.com/manuals
for complete specifications.
Connecting the NI 9235
The NI 9235 provides connections for eight 120 Ω quarter-bridge
input channels.
8 | ni.com | NI 9235 Getting Started Guide
Figure 1. NI 9235 Pinout
1
2
3
4
5
6
7
8
9
10
11
12
EXC1
AI1
RC1
EXC3
AI3
RC3
EXC5
AI5
RC5
EXC7
AI7
RC7
EXC0
AI0
RC0
EXC2
AI2
RC2
EXC4
AI4
RC4
EXC6
AI6
RC6
13
14
15
16
17
18
19
20
21
22
23
24
NI 9235 Getting Started Guide | © National Instruments | 9
Table 1. Signal Descriptions
Signal Description
EXC Provides the excitation voltage stimulus
AI Measures the bridge voltage
RC Provides the quarter-bridge completion
Connecting a Quarter-Bridge Sensor
You can connect quarter-bridge sensors to the NI 9235.
Figure 2. Connecting a Quarter-Bridge to One Channel
EXC
AI
RC
NI 9235
10 | ni.com | NI 9235 Getting Started Guide
You must connect each EXC terminal to only one strain gage to
maintain the channel-to-channel crosstalk performance of the
module.
For the best system accuracy, observe the following conditions
when connecting to the NI 9235.
• Set up the connections to EXC and RC with equal lengths of
an identical wire type and gauge.
• Connect the AI terminal directly at the sensor instead of
shorting AI to RC directly at the terminals.
Connecting Wires to a Spring-Terminal
Connector
Complete the following steps to connect wires to the springterminal connector using the flathead screwdriver that is included
with your C Series module or a flathead screwdriver with a blade
smaller than 2.3 mm x 1.0 mm (0.09 in. x 0.04 in.).
NI 9235 Getting Started Guide | © National Instruments | 11
Figure 3. Connecting Wires to a Spring-Terminal Connector
1 2 3
1. Insert the screwdriver into a spring clamp activation slot to open the
corresponding connector terminal.
2. Press a wire into the open connector terminal.
3. Remove the screwdriver from the activation slot to clamp the wire into
place.
12 | ni.com | NI 9235 Getting Started Guide
High-Vibration Application Connections
If your application is subject to high vibration, NI recommends
that you use the NI 9965 backshell kit to protect connections to
the NI 9235.
NI 9235 Getting Started Guide | © National Instruments | 13
Where to Go Next
Located at ni.com/manuals Installs with the software
CompactRIO
NI CompactDAQ
RELATED INFORMATION
C Series Documentation
& Resources
ni.com/info cseriesdoc
Services
ni.com/services
NI 9235 Datasheet
NI-RIO Help
LabVIEW FPGA Help
NI 9235 Datasheet
NI-DAQmx Help
LabVIEW Help
14 | ni.com | NI 9235 Getting Started Guide
Worldwide Support and Services
The NI website 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.
Visit ni.com/services for NI Factory Installation Services, repairs,
extended warranty, and other services.
Visit ni.com/register to register your NI product. Product
registration facilitates technical support and ensures that you
receive important information updates from NI.
A Declaration of Conformity (DoC) is our claim of compliance
with the Council of the European Communities using the
manufacturer’s declaration of conformity. This system affords the
user protection for electromagnetic compatibility (EMC) and
product safety. You can obtain the DoC for your product by
visiting ni.com/certification. If your product supports calibration,
you can obtain the calibration certificate for your product at
ni.com/calibration.
NI 9235 Getting Started Guide | © National Instruments | 15
NI corporate headquarters is located at
11500 North Mopac Expressway, Austin, Texas, 78759-3504. NI
also has offices located around the world. For telephone support
in the United States, create your service request at ni.com/support
or dial 1 866 ASK MYNI (275 6964). For telephone support
outside the United States, visit the Worldwide Offices section of
ni.com/niglobal to access the branch office websites, which
provide up-to-date contact information, support phone numbers,
email addresses, and current events.
Refer to the NI Trademarks and Logo Guidelines at ni.com/trademarks for information on NI
trademarks. Other product and company names mentioned herein are trademarks or trade names
of their respective companies. For patents covering NI products/technology, refer to the
appropriate location: Help»Patents in your software, the patents.txt file on your media, or the
National Instruments Patent Notice at ni.com/patents. You can find information about end-user
license agreements (EULAs) and third-party legal notices in the readme file for your NI product.
Refer to the Export Compliance Information at ni.com/legal/export-compliance for the NI
global trade compliance policy and how to obtain relevant HTS codes, ECCNs, and other import/
export data. NI MAKES NO EXPRESS OR IMPLIED WARRANTIES AS TO THE ACCURACY OF
THE INFORMATION CONTAINED HEREIN AND SHALL NOT BE LIABLE FOR ANY ERRORS.
U.S. Government Customers: The data contained in this manual was developed at private
expense and is subject to the applicable limited rights and restricted data rights as set forth in FAR
52.227-14, DFAR 252.227-7014, and DFAR 252.227-7015.
© 2008—2015 National Instruments. All rights reserved.
374645B-01 Oct15
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