My voltage input reading are floating around and cant seem to get an accurate reading of any kind. What is causing this?

[jtoronyi]

Im trying to input a DC voltate on channel 1. So i hook up +5 to the channel 1 analog input, and hook up ground to the AIGND. When i measure it in continous time, i get a reading of -1.3 V, when i move the cable connecting the NI board and the DAQ, the voltage jumps around. I even tried connecting AIGND straight to channel 1 analog input, and read a voltage of 2.3, but its not stable, it jumps around a lot. What is this problem. please help

[markwysong]

This is going to depend on how you have your DAQ board configured. In differential mode, the positive input is channel 0, but the negative input is channel 8 (for 8 differential/16 single ended MIO boards. Channel 32 is - on 32 differential/64 single ended MIO boards). (Similarly, chan 1 (+) and chan 9 (-) are the next channels, etc).

For single ended mode, chan 0 is the +, and AIGND is the -.

I suspect you have your board in differential mode, and your - is not connected to the correct pin; therefore, your voltage is floating.

Mark

[jtoronyi]

Thank you very much. That was it, i cant beleive i made an error like that, but i guess thats what i get for not reading the instilation manual completely (3rd day using labview and i love it already). Thank you very much