I am using a USB6210 and LabVIEW 2012. I have a string pot that I am reading (ai0 on pins 15 and 16 differential) and a linear displacement laser (ai3 on pins 21 and 23 differential) that also outputs a voltage. I have a car battery that powers the pot and also the laser unit which then has a voltage output on it which I am measuring, but if I power both at the same time the laser causes the string pot to go crazy. I isolated the laser with a DC/DC converter. Now I can get a good signal on each independently but not at the same time, because I can only refrence AI GND one system at a time. Is there a fix to this? When I connect them both to GND it goes back to chaotic noise as it did before I isolated the laser. I am fairly confident that what I am doing is trying to break some law of physics. Two channels can't be this hard! Any advice or comments, Ill gladly share any more details to try and get this figured out.
