Apparent cross-talk that is caused by software

[ggaines]

I have several channels setup that test out find in MAX. When I acquire data on several channels(continuous acquisition to spreadsheet.vi), the signal for one of the channels appears noisy and the average is incorrect. If I acquire only one channel, the signal appears clean and is teh correct value. NO HARDWARE CHANGES during this process. I have tried differential, single referenced, and differential but still grounded and get the same kind of results. I am using a laptop card (AI-16X-50) with a SCB-68 accessory board which is grounded. Labview 7 with the latest MAX and drivers support and Windows 2k.

Thanks

[Ben]

This was posted in the NINews I recieved this AM.

6. My Laptop Reads a Floating Voltage from a Grounded Source
Laptop computers performing measurements can create a floating situation
similar to using a floating source. This article discusses measures you
can take to make sure your readings are accurate.
http://digital.ni.com/express.nsf/bycode/nn0104b21


That may help witht the noise on the channel.

Otherwise;
Is the device driven by that channel a high impeadance device?

Ben

Ben Rayner
Certified LabVIEW Developer
www.DSAutomation.com