pci-6111 dc voltage dropping to zero

[Fuqface]

Hi,  We have a PCI-6111 Daq card.  When we put a DC voltage across any of the AI channels the voltage drops to zero after a split second. We have checkedthe channel voltage with an oscilloscope and it is indeed 5 volts high.  Upon applying the 5V the DAQ card reads a sharp spike usually less than 5V then drops to zero volts.It seems that the card can't hold a voltage.ALso, on the AO channels we put out a sine wave to an oscilloscope and we get a sine wave that has its negative peaks truncated.  So the bottom wave peaks are flattened.Is this indicative of a bad card?Thanks.

[AnalogKid2DigitalMan]

Ff:
Your description of the 5V spiking and then going to 0 sounded like AC coupling to me. I looked at the manual, and indeed the card does support AC and DC coupling so you may want to make sure you are set to DC coupling. Here's a link to an older manual: <a href="http://www.ni.com/pdf/manuals/321759e.pdf" target="_blank">http://www.ni.com/pdf/manuals/321759e.pdf</a>
There are newer&nbsp;manuals available here: <a href="http://sine.ni.com/manuals/main/p/sb/navsRel?q=pci-6111" target="_blank">http://sine.ni.com/manuals/main/p/sb/navsRel?q=pci-6111</a>
Regarding analog ouputs, that does seem odd. You may want to try running diagnostics, here's a link to that, do not know what version DAQmx you are using so you may have to use an older version (links on that page): <a href="http://joule.ni.com/nidu/cds/view/p/id/566/lang/en" target="_blank">http://joule.ni.com/nidu/cds/view/p/id/566/lang/en</a>
Let us know the results.
&nbsp;

[Fuqface]

Actually we were measuring the voltage with reference to the AI ground.&nbsp; Changing it to the AI0- fixed the problem. Thanks.

[AnalogKid2DigitalMan]

Very good. Are the analog outputs behaving properly when reference to the proper ground level?