09-15-2014 11:02 AM
Hi,
I have a problem that a PCI 6251 card records a constant voltage, but it should be 0 with small fluctuation. In the test panel within Mesurement & Automation, the input is one single value -10.6v with no fluctuation at all (shown in the attached figure). I try to reset the device but it is the same after reseting. Is this the problem with my card or something else? How can I solve this problem?
Thanks a lot.
Sincerely,
Jie
09-15-2014 02:48 PM
09-16-2014 06:02 AM
BIAS current !
REad the user manual on how to make voltage measurements.
Oh, and your input channel could be blown (protection diode to -V got resistive 😉 ) but usually a simple path for the bias current is missing.
09-16-2014 01:45 PM
Hi, I have 8 input differential measurement. ai 0 is ch 1 and ch9. ai 1 is ch 2 and ch 10.... ai 7 is ch 7 and ch15. I plug and unplug the connector for the card and now the input reading is ~ -0.0016V (shown in the attached Dev 2 figure). But it should be 0V. I also have two the other cards (Dev 1 and 3) and they have the same set up as dev 2. The other two cards reading is ~ 0V (shown in the attached Dev1 and 3 figures). I use a multimeter to measure the voltage for the terminal block and readings are the same as shown in the figures. Is the -0.0016V within the error arrange? Or there is problem with my card?
Thanks a lot!
Sincerely,
Jie
09-16-2014 01:50 PM
Hi,
I checked fuses for the input channels and the fuses are fine. I use multimeter measure the inputs and it should be 0V. However, the input for the terminal block is ~ -0.0016V (which is the same as the reading on computer, I have explaination and figures in my last post). Also I use the other two cards that have the same setup with this problematic card. The other two cards readings are 0V.
Thanks a lot.
Sincerely,
Jie