06-05-2007 03:57 PM
06-05-2007 05:53 PM
The 700 does not support simultaneous sampling, that is the front end circuity is switched between inputs to the analog to digital converter.
Here's a link to the manual:
http://www.ni.com/pdf/manuals/320676d.pdf
What you are seeing is normal. Due to the high input impedance and a slight capacitance on the front end circuity, unconnected inputs may tend to float to values to their adjacent connected channels. If you connect the unused inputs to ground, they should settle out a 0 volts. To test your code and hardware, I suggest you try hooking up each channel to a different voltage and see if you graphs match the expected results.
06-06-2007 09:53 AM
06-07-2007 12:37 PM
06-07-2007 01:14 PM
They have 16 usable inputs in single ended mode, and 8 in differential mode.
Just connect your signals up to the appropraite channels and read them. Once they are connected to a source, the source will act to bleed the adjacent channel crosstalk away.
No need to ground them out and connect to the signals prior to reading.