I have connected a signal generator with the (+) to AI 0 and (-) to AI8 of the daq board (M 6259). Both the PC and the signal generator is earthed to the electrical earth through the plug socket. The input wave form is OK but is drifting from left to right on the screen (especially for frequencies below 100 Hz). Do I have to connect bias resistors between AI8(ie - input) and AIGND? If so what would be the values.
You need to determine if the output of the signal generator is referenced to ground or is floating. It does sound like the DAQ and the generator are not referenced the same. Try a 100K ohm resistor from AI8 to ground.
