PCI 6220 linux

[cfiene]

ERR   that should read UNREASONABLE data from executing aiex1 and aiex2 with the pci-6220

[AlanArmstead]

How are you connecting your signals?

As they are written, the examples set up the analog input channels in differential mode.  So, to read 0V on ai0, you should short ai0 to ai8 (connect pin 68 to pin 34 with a wire).  To read a voltage source, connect ai0 to V+ and ai8 to V-. 

-Alan A.

[cfiene]

That was it.  I had assumed it was ai0+/ai1- (pin 68/pin 33)  not ai0+/ai8- (pin 68/pin 34).
There is nothing in the 622x specification pinouts to indicate differential wiring (page 11 Figure 1 of 371290d.pdf).
 Still a bad assumption on my part.

Tying both + and - to aignd (pin 67) gets the reading down to a single bit of jitter, otherwise I'm getting about 4bits of jitter.