SCXI Unit

[Abhishek Gupta]

Hi,

Currently I am using the NI DAQ system with SCXI 1000 chasis and SCXI 1321 terminal block module. I am using it for measuring strain through strain gauges using half bridge configuration. I have performed a dummy test with zero load at 80C temperature, but the results are very strange.  As its suppose to give zero strain at no load condition, but it gives some considearble finite value of strain ~50-60 microns, as well the graph shows some odd variation in strain.

So, my first question is :

how to resolve this problem? I am attaching the graph obtained from this experiments. So, please see and give me some suggestions.

My 2nd question is:

I want to change the half bridge configuration to quarter bridge configuration. So, what changes will be required in the terminal block ? As, i know, there is some change for the resistor setting (already installed) , which need to by pass for half bridge but needs to include for quarter bridge. Just wondering, how to do that?

Any help will be appreciated.

Thanks.

[devchander]

Hi,

Are you not using the  Nullling Potentiometer circuit present on SCXI 1321?

This manual expains how to do it.

Plus it also shows connection diagram for quarter bridge connection.

Hope it helps

Regards

Dev

[Abhishek Gupta]

Hi,

I am already using the Nulling potentiometer circuit in SCXI 1321. But it still gives the similar results as i attached in my previous post.

Thanks for ur help.

Abhishek

[Hal_L]

Hi Abhishek,

The 80ºC temperature that you are operating under is outside of the supported range for this SCXI system. I recommend moving your system to a place at room temperature and performing your acquisition there. Please do this and let me know what results you receive.

Regards,
Hal L.

[Abhishek Gupta]

Hi Hal,

The system is not inside the enviornmental chamber. Its outside at room temperature. Only the sample is in the furnace.

Abhishek

[Hal_L]

Hi Abhishek,

Which SCXI hardware are you using and how do you have it configured? Also, if you apply a strain to the strain gauge, can you notice a difference in the graph?

A couple of things that I would like you to do are to:

1. Check your connections on the system
2. Check your grounds and make sure that everything is grounded and there are no ground loops.

I hope this helps.

Regards,
Hal L.