I am trying to read analog voltage from a very simple device (a dial outputting between -2.5 and +2.5 V, depending on dial position) to a WindowsXP pc using a PCI 6221 card connected to a SCB-68 block. I first tested the device using a scope, and it outputs proper signal between its two lines. (the dial is receives power via a simple DC transfo). However, when i connect the two cables to point 65 and point 31 as indicated by the connection diagram for ai2, i get a signal in MAX I don't understand at all. They seem like AD signals !
I tried changing from differential to RSE and NRSE, I tried other ai numbers, but nothing seems to help.
and the weird part : if i connect the scope pins to the SCB points, the scope is reading nutty signals as well ! It is like as if the SCB introduces
signal changes.
I'm probably doing something completely stupid, but since I'm completely unexperienced in ellectronics, I really don't understand most of the manuals.
can anyone point me in the right direction here ? The card is properly recognised by windows, and passes the self-test succesfully
