PCI-6110 needs calibration often to fix DC offset.

[fastball09]

I have a system with two MIO cards in it, PCI-6110 and PCI-6251. We only use one DAQ board at time but whenever we switch from the PCI-6251 to the PCI-6110 a 90 mV (I don't remember the polarity) dc offset is registered on the analog inputs. Running the self-calibrate in Measurement & Automation Explorer fixes the problem temporarily but we need to calibrate every time we switch from the PCI-6251 to the PCI-6110. When we switch from one card to the other all we do is unplug one cable and plug in the other cable to our experiment. I have even verified the 90 mV dc offset with 50 ohm loads connected to the analog inputs. What’s going on and why? I have never seen this before and I've been doing high performance Labview/hardware systems for ten years. ~ Mike

Message Edited by fastball09 on 03-02-2009 08:52 PM

[Hillman]

Hi Mike,

Good afternoon and thanks for your post, I hope your well today.

This is indeed an usual problem. So your post suggests that if you just use the PCI-6110 on its own for a long period of time the AI stays calibrated? and the signal is indeed the form you expect - if so, this probably rules out a damaged PCI-6110. Do you have another board you can try? - ideally another 6110.

Do you see the same issue when you switch between the 6110 and the 6251?

What type of signal are you measuring, it could well be your circuitary - such as bias resistors or (very unlikely) an issue with the cable. 

Other likely issues could include,

1. Are you switching with live voltages on the other end of the cable, it may be a good idea to disconnect both ends of the cable.

2. In your code, do you start the DAQmx task before or after the cable is attachted to the card? It is best to make the connection and then start the task.

3. If you aren't alter the circuit setup at the other end of the cable, are the pinouts the same for the two cards? It may well be your sending voltages to the wrong pins when you switch the cable.

Just some ideas,

Please let me know your thoughts,