03-15-2012 05:26 PM
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.
Solved! Go to Solution.
03-18-2012 04:52 PM
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:
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: