Help on multichannel analog input using DAQ assistant

[seanxl04]

I'm using a National Instruments BNC-2110 DAQ board to collect multiple analog signals from a function generator. I'm using the DAQ Assistant VI in LabVIEW v8.2 to take in the signals, and then display the signals on the front panel.

I have 3 channels setup in the DAQ assistant corresponding to 3 physical channels. When I have a function generator hooked up to only one physical channel (e.g. AI 0), I get that signal not only in that channel, but the other two as well.

How do I fix this so only the channel connected to the function generator gets data and the other channels show nothing?

I've attached my VI for reference.

Any help would be really appreciated!!

Thanks a lot.

Message Edited by seanxl04 on 02-12-2008 03:12 PM

[Dennis_Knutson]

I'm surprised that you are reading anything with just a BNC-2110. It's just a dumb terminal block and not a data acquisition device.

With whatever DAQ device you actually have, it sounds like you are experiencing normal crosstalk. See this.

[NI-Bongo]

Hi,

As Dennis mentions, this may be crosstalk.  Are the signals on the other channels attenuated or the identical signals?  If they are attenuated, it is likely cross talk that is causing the issue and the article Dennis references is a good one to look at to reduce these effects.  If the identical signal is being shown on all the graphs, there may be something going on in your code when you split the dynamic data into the separate graphs.  What type of signal are you looking at and which DAQ device is the BNC terminal block connected to?

[NI-Bongo]

Hello again,

Also, I'm curious to know if you are seeing this behavior on the top graphs or the bottom graphs in your VI.

[seanxl04]

Hi,

Thanks a lot Dennis and John, after reading those posts I do believe I am getting cross-talk. I'm just going to ground the channels that aren't being used to get around this.

I really appreciate your help!

Thanks again,

Sean