Wouldn't it be easier to simply record the counter value as you ouput it and have it side by side with the voltage you measure from the tissue? This way you won't need to wire the counter output signal back to an AI channel.
Otherwise please take a look at the following document for proper wiring considerations.
Thanks for replying. Could you tell me how to record the counter output value without actually connecting it to an AI channel? I know I can calculate what the counter state _should_ be from the variables I give the Counter Output Task, but I was hoping to be a bit more accurate with the timing, just in case the counter output pulse appears e.g. 101ms after triggering rather than the 100ms I have specified.
I have read though the article on analog signal wiring, but I am still no wiser as to why recording the CO with one AI affects the voltage on other AI channels, even with both inputs in differential configuration, which I'm guessing should avoid problems with DGND and AGND being different?
Just to clarify when you changed the mode to "differential" did you also change the physical wiring as shown in the wiring diagram in MAX? I assume you did, but that's something I need to verify.
The following Knowledge Base: How Do I Eliminate Ghosting From My Measurements? will help you in eliminating the ghosting that you are seeing.
Based on your description, it seems like there is a delay between the time you output a signal with your Counter Output task and reading the response from the tissue. This is the delay of your unit under test. The counter output signal most probably will be read faster on AI 0 than the tissue's reponse on AI 1. When you use a multifunctional DAQ, there is some interchannel delay when you scan multiple channels as there is only 1 ADC for all AI channels. If you want to have a perfect simultaneous sampling, you will need a S series board, which features 1 ADC per AI channel. That all depends on the goals of your experiements.
Hope this helps!