Measuring resistance of a strain gauge (quarter bridge type II configuration) using DAQ device

[JP187]

Hello,

I have two strain gauges in quarter bridge configuration bonded on a carrier, which is attached to the test specimen. Please refer to attached image for more information. One strain gauge is active (lets say R4) and another one is dummy (R3, which is placed transverse to the principal axis of strain). I want to measure the resistance of the R4. I have a NI TB-4330 front mounting terminal block with NI PXIe-1073 chasis. With the help of user manual i have completed the circuit. But in Labview program, daq assistant doesn't show any supported physical channel for the resistance measurement. Can you please tell me how can i measure the resistance in my case?

[GerdW]

Hi JP,

so you have a TB-4330: this is only a mounting terminal!

Do you also have the needed DAQ devices? Are they mounted in your PXI chassis?

Are they available in MAX?

Before playing with DAQAssistent (which I do not recommend) you should try to create your DAQmx task in MAX!

[JP187]

Hi GerdW,

thanks for the reply. I have PXIe-1073 chasis with 5 slots and only one front mounting terminal block i.e. TB-4330. Both the devices are available in MAX. I had tried to create DAQmx task in MAX, but i ran into the same problem. It didn't show any supported physical channel for resistance measurement.

Regards,

JP

[GerdW]

Hi JP,

what is mounted in those PXI slots? Where do you mount the TB4330 to?

Can you show a MAX screenshot with all devices visible?

[JP187]

Hi GerdW,

TB-4330 is mounted to slot 2 of PXIe-1073. Please check the images in the attachment.

Regards,

JP

[GerdW]

Hi JP,

TB-4330 is mounted to slot 2 of PXIe-1073.

TB4330 is mounted to a PXIe4330 DAQ card. You should have been able to tell that right from beginning…

Are there any channels availabe for your PXIe4330 (aka "PXI1Slot2")? Can you create a task using one of those channels with MAX?

[Ben]

I have two of those modules in a PXIe chassis acquiring from 16 strain gages that have TEDS support and they work fine.

As Gerd has been urging you...

Create a Task and choose "strain" and you will eventually get a test screen that will let you poke a the setting to adapt to your strain gages.

Go ahead and "Try it! You will like it".

Once you have a task defined it can be used to generate a config sub-VI and an example that can be used in LabVIEW.

Ben

[Ben · Accepted solution]

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@JP187 wrote:

...It didn't show any supported physical channel for resistance measurement.

Regards,

JP

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It just hit me that you were looking for resistance when the measurement type is strain.

Ben

[JP187]

Hi Gerdw,

Yes, there are channels available for PXIe-4330. I had created DAQmx task using one of those channels and measured the output of Force sensor.

Best Regards,

JP

[JP187]

Hi Ben,

I think you are right, the measurement type is strain. Once i have strain value, using the equation of Gauge factor, i can calculate the value of change in resistance.

Best Regards,

JP