strain measurement using NI 9944 and NI 9237

[stonecsu2000]

I am using NI 9237 and NI 9944 based on NI 9127 DAQ for strain measurement. The manual for NI 9237 says the module can supply excitation voltage. Where and how do I specify the voltage? Can I do it in SignalExpress?  Thanks,

[J_Thomas]

Hi stonecsu2000,

The excitation voltage for the NI 9237 can be set in several different ways.  The easiest way to do this is to configure a new DAQmx strain task.

For Signal Express:

Add a new step.  Select Acquire Signals >> Analog Input >> Strain.  On the Configuration tab for the Step Setup you can set the excitation voltage.  The property is called “Vex Value.”

In Measurement and Automation Explorer:

Created a new DAQmx Task Analog Input Strain task. The excitation can be set on the Configuration tab for the task. The property is also called “Vex Value.”

[stonecsu2000]

Thanks a lot for the help. But I am ranning into new problems. As I mentioned before, I am using NI 9237 and NI 9944 for a quarter bridge strain gage (actually, one single gage in my case). I connected the NI 9944 to NI 9237 through a RJ 50 cable, and connected my three-wire gage into NI 9944. But I was not able to get some meaningful reading. Did I miss something in terms of the hardware set? Do I need an amplifier?

[Elizabeth W]

Hello,

You shouldn't need an amplifier.  It sounds like you may have connected something incorrectly.  Please refer to KnowledgeBase 47SGM5CY: NI 9945 or NI 9944 with an NI 9237 Connection Guide for more information about how to connect your strain gage.  If the problem persists, please post back and let me know exactly how you have wired everything.

Hope this helps!