straingage

[Echoman]

Is it possible to measure 350 Ohm Wheatstone bridge (loadcell) using PCIe-6341 with SCB-68A?  Can I use the Digital +5V for excitation high voltage and Digital Ground for excitation low voltage?  Then I was going to use 2 analog inputs, one to measure Vo and the other to measure Vex.

[Stranman · Accepted solution]

Yes, its "possible" but I would NOT recommend this implementation:

1.) The digital outputs are meant for high impedance inputs (to minimize current sourcing)

2.) The digital out voltage is not regulated; therefore, even using the lowest +/- 0.2V range AI to read the unamplified bridge voltage, your measurements would change with the unregulated bridge excitation.

So yes, it should work, but I'm not sure of the repeatibility or induced error of your measurements.  Also, if you were cycling other digital outs on and off, that would most likely induce a change to the excitation as well.

A better implementation would be with a NI strain gage card or third party strain gage conditioner/amplifier

(ex. DataForth)

- P

Editted: Grammar