usb 6210 analog voltage reading problems

[nwiman]

Hi,

I am trying to wirte a program that will read multiple voltages or currents from single wires so that I can maximize channel use on my usb 6210. I have an external power source, your basic DC power supply. I wired it to NRSE configuration such that the voltage sources that I would like to measure are sometimes connected to DC+ from the power suuply (trying to measure when these connections are made by an insect) and come into terminals AI0-AI15, with AISENSE returning to the DC- terminal on the power supply. As far as I know, there are no ground loops in my system, I have thoroughly read the field wiring manual. Right now, only 8 of the 16 AI terminals are wired, you will see in the block diagram. 

Here is my issue: when one of the inputs is connected to the power source (running approx. 2V), all of the other waveforms are strongly affected. Attached images illustrate this. I need independence between my channels so that when one wire is connect the other waveforms don't jump with it. I would really like to see distinct waveform patterns triggered by the connection, which will have varying degrees of resistance depending on what the insect is doing.

I am on XP and I saw some MS hotfix for potential usb data problems referenced in MAX, but I don't know if this is the problem I have, the hotfix link tells me its unavailable.

Any guidance in this matter would be much appreciated.

[Dennis_Knutson]

If you are seeing signals on unconnected channels, that is normal and is called ghosting. Please search for that.

[nwiman]

I found lots of info on ghosting. How to apply this knowledge to my problem is another matter. I see that I need to slow my sampling rate, and I found the DAQmx timing property node but I don't know how to apply this in my block diagram. Also it looks like creating dummy channels would be a good way to go but I cant get this to work either.

Thanks.