I have a DAQPad-6015 and I am reading ACH0. However, when I read any of the other channels, the data is almost identical. Looking at the graph, the waveform from ACH0 (connected to an accelerometer) and another channel (ACH5 in this case, not hooked up, so it should be just noise) are right on top of each other. Looking at the data, they are in fact different by a few percent.
My accelerometer gives +/- 5V output, so I really don't see a way there should be that much leakage or coupling or any other physical effect. However, because the data is not exactly identical, I have trouble pointing the finger at my code.
Also, running each channel seperately works fine. That is, ACH0 by itself gives accerometer data, usually about 3V in amplitude centered around zero. ACH5 by itself gives a few 10s of millivolts of noise centered around zero. However, when running them both at the same time (wiring Dev1/ai0, Dev1/ai5 to the DAQmx Create Channel VI, then ACH5 rises to almost exactly follow ACH0.
I'm using Labview with the mx DAQ VIs. Is there any reason that channels that are not hooked up to hardware should be reading similar data as the neighboring channels?
Thanks,
Casey