voltage spikes on analog outputs of 6255 and 6071E

[sumitm]

I am using PCI 6071E and PCI 6255 boards in desktop PC’s, and have been observing large voltage spikes on the analog output channels. A typical pair of spikes is shown in the attached file (amplitude 4 V, main spike width ~100 ns). The AO0 and AO1 outputs of a PCI 6255 from a SCB-68 connector block were connected to an oscilloscope with 1 MOhm impedance, without any other load attached.

The spikes occur occasionally (once every couple of hours to a day). Spikes occur at various times, when the PC powers up, when the PC is on and not running any programs, and also when Labview VI’s are loaded but not running. I have not observed any spikes when Labview VI’s are actually running.

System details: Desktop PC, Windows 7 (32 bit) with 4 GB RAM. Labview 2009 and MAX 4.6 installed (but not necessarily running, as I mentioned). Two PCI 6255 and one PCI 6071E installed.

I have observed similar spikes on two other similar systems with PCI 6071E cards. I'd greatly appreciate any insight into this problem.

Sumit

[0utlaw · Accepted solution]

Hello Sumit,

I tried opening the image file you provided, but was unable to.  Could you try uploading that again? 

Also, I have a few questions that might help us pin down the problem:

1) Do you see the same behavior when you have already loaded and run a VI (i.e. you run, then close the VI)? 

2) Do you see the behavior after opening a test panel to the card in MAX?

3) What drivers are you currently using? You may want to consider downloading a more recent version of your drivers, which can be found here:

http://www.ni.com/drivers/

You may also want to ensure that the drivers are configured to load at boot, rather than at first call.

4) Have you tried observing the output across a load?

In the meantime, I would recommend self-calibrating the cards in MAX:

http://zone.ni.com/devzone/cda/tut/p/id/3696#toc2

[sumitm]

Thanks, Tom. Updated the drivers, and I haven't seen any spikes in a while.