Input floating at 100mV DC

[Frustrated]

I recently discovered my test stand has a +100mVDC offset. If I ground the input to the A/D card, I still read 100mVDC. If I measure from the DC ground to the case of the computer, I have 100mV. After looking at our data, this machine has been running this way since day one when it was delivered ( 4 months ). Since I did not wire the machine, I am at a loss as to what I should look for in the wiring. Any ideas ?

[Stefan S.]

Have you looked at the analog input mode of yout DAQ board? It just might make a difference whether you choose "referenced single ended" or "non-referenced single ended". Usually you can change that in the NI Measurement and Automation Explorer.

Maybe you already know, nevertheless all the best,
Stefan