Low Voltage Garbage

I just got the Comedi calibration working properly.  Now, when I measure 
higher voltages (7V for instance), the difference between my measurement at 
the terminal board with a voltmeter and my measurement from Comedi are the 
same within about +/- 0.02V.  I'm using an NI-6036E DAQ board set on the -10V 
to +10V range.  I'm happy with that.

But my measurements for low voltages are garbage.  When I measure -0.06V with 
my voltmeter, I can get anything between about +0.05V to about -1.5V from 
Comedi.  I ran 10k resistors between an AI Ground input pin and the pin for 
each channel, and that is keeping the voltage readings from floating up to 
large voltages when there is little or no input voltage.  But it doesn't make 
my low voltage readings much better.  I would just like for my low voltage 
readings to be as accurate as my higher voltage readings.  Is that possible 
using the higher voltage settings?  Do you recommend a higher resistance?

Thanks for your help.

The next time you edit the Comedi Reference document, it would be a really 
good idea to include calibration instructions.

Best Regards,

Heather

Received on 2006-08-22Z21:41:19