Have SCXI with 1102: random voltage drift

[VAS1]

Have SCXI with 1102: been running for years with no problems. Now all channels at same time increase in voltage by .02 Volts. This happens randomly the slowly settles down back to normal. Have input a 2.5 volt test signal into unit with all other channels disconnected. same outcome. Any ideas Thanks

[Eric_LV]

Hey VAS1,

Has anything been changed about the SCXI set up since it had been working?  Have you tried using different slots or a different chassis if you have one?  It sounds like this could be a grounding issue of some kind.  Can you tell me more about your set up and your 2.5 volt test? what kind of source did you use?  I think I can help but I'd like to know more about your issue before I suggest anything to fix it.  

[VAS1]

No changes have been done to the system. Have not switched slots on the SCXI Yet. I to, thought it was a grounding  problem, so I remove the SCXI 1300 cable box and put a spare in. I connected a fluke calibration unit and  applied a 2.5 volts test signal to several channels, one at a time. Made a VI graph and let the unit run. Several time within and hours, and at random  intervals this voltage increased  on average  .02 to .07 volts then it would settle back down to 2.5 volts. This is a significant error for us as it may represent 30 PSI or more in a test. The SCXI is connected to a 6063E card on a duel core intel computer, running Labview 7.1. This unit has been running tests for, maybe 7 years with no problems. So after more testing today I'm thinking its the 1102 card and/or the 6063E Card or the cabling between them

[Eric_LV]

The next step for trying to find out where the problem is is to try out another SCXI module if you have one.  If you have any other device to test your 6063E card that would be helpful too.  I would think it is likely the 1102 that is having the problem but if you can test another SCXI module if you have one we can find out for sure.  I would be somewhat surprised if the problem was the cabling between the card and the SCXI but if you are using a terminal block connector at the front of your 1102 module that could be causing the problem, so if you perhaps had another connector to test out we can check that too.  If you don't have any other devices to test out this might get a little trickier pinpointing which device is having the problem.  

[VAS1]

Did have a few spare cards around. Tried the 1102 first then the 6063E card. It looks like it was the 6063E card. Put the spare unit in and have had no troulbe.

Thank you very much for your input.

Tim