differential signals

[clint100]

I'm trying to do a confidence check on a PXI6230.  On my Test Set I have to generate a SE signal ( PXI6230 say AO_1) and send it out to the UUT.  Prior to testing I check this signal by looping it back to a differential input ( AI_3 ref to AI_7)  on my 6230.  My question is am I better off generating 2 individual SE and feeding them back to AI_3 ref to gnd and AI_7 ref to gnd or can I generate a single differential signal and use my diff input ( AI_3 and AI_7) for the conf check??  Can you even generate a differential signal??  How?

Thanks

[Dave.C]

Hi,

I saw your post and thought you might find the following discussion interesting.  It's also on our forums.

http://forums.ni.com/t5/Multifunction-DAQ/PXI-6230-and-Differential-Measurements/m-p/2267230

[sth]

It depends on what you are trying to accomplish as a confidence check.  If you are trying to check the differential linearity of your system then yes. You need to generate two output voltages referenced to ground and then check the input vs the difference between the two voltages.

If you are just trying to check the accuracy and timing of the singals then you can just send in a single output to your differential measurement and the differential will use the low side of the signal generator as the negative refrence.

Usually to eliminate the noise of a bias current on a high impdenance input you need a path to ground so a high value resistor to ground may make your measuerments much better.