National Instruments NI 9236, NI 9235 User Manual

OPERATING INSTRUCTIONS AND SPECIFICATIONS

NI 9235/9236

8-Channel, 24-Bit Quarter-Bridge Analog Input Module

DeutschFrançais

ni.com/manuals

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 you need for the modules you are using. For information about installing, configuring, and programming the system, refer to the system documentation. Visit and enter

cseriesdoc for information about C Series

ni.com/info

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.

NI 9235/9236 2 ni.com

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 you are 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.

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 9235/9236 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 9235/9236 4 ni.com

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.

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.

EXC0 AI0 RC0 EXC2 AI2 RC2 EXC4 AI4 RC4 EXC6 AI6 RC6

Figure 1. NI 9235/9236 Terminal Assignments

NI 9235/9236 6 ni.com

1 2 3 4 5 6 7 8

9 10 11 12

EXC1

AI1

RC1

EXC3

AI3

RC3

EXC5

AI5

RC5

EXC7

AI7

RC7

Yo u can 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.

EXC*

AI**

RC*

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.

Figure 2. Quarter-Bridge Connections for the NI 9235/9236

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

NI 9235/9236 8 ni.com

Wiring for High-Vibration Applications

If an application is subject to high vibration, National Instruments recommends that you use 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 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 u must 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 you to 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.

NI 9235/9236 10 ni.com

EXC

120 Ω

Bridge

Completion

Resistor

50 kΩ

Resistor

Shunt

–

Filtered

Differential

Amplifier

ADC

+ –

Excitation

2.0 V

Bridge

NI 9235

Figure 5. Input Circuitry for One Channel of the NI 9235

EXC

350 Ω

Bridge

Completion

Resistor

100 kΩ

Resistor

Shunt

–

Filtered

Differential

Amplifier

ADC

+ –

Excitation

3.3 V

Bridge

NI 9236

Figure 6. Input Circuitry for One Channel of the NI 9236

The NI 9235/9236 also includes filters to prevent aliasing. The filters on the NI 9235/9236 filter according to the sampling rate. Refer to the Understanding NI 9235/9236 Filtering section for more information about filtering.

NI 9235/9236 12 ni.com

+ 26 hidden pages

National Instruments NI 9236, NI 9235 User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual

Safety Guidelines

Safety Guidelines for Hazardous Locations

Special Conditions for Hazardous Locations Use in Europe

Special Conditions for Marine Applications

Connecting the NI 9235/9236

Figure 1. NI 9235/9236 Terminal Assignments

Figure 2. Quarter-Bridge Connections for the NI 9235/9236

Connecting Wires to the NI 9235/9236 Connector

Figure 3. Connecting Wires to the NI 9235/9236 Connector

Wiring for High-Vibration Applications

Figure 4. NI 9965 Connector Backshell

NI 9235/9236 Circuitry

Figure 5. Input Circuitry for One Channel of the NI 9235

Figure 6. Input Circuitry for One Channel of the NI 9236