Pauses while running

[Jeremy@Thermadyne]

I am using a cDaq-9172 box with two 9211, a cRIO-9215, and 9237 module.  My problem is that while I am running the vi I get a short pause every few seconds.  No matter what I set the sampling rate too, I get the same pauses.  This is causing problems in my datalogging, because when the pause occurs it only records a few data samples for that second and then goes back to the normal sampling rate until another pause.  Any suggestions?

[Travis_W]

Hi,

I'm assuming you're using software timed I/O on all of these modules (on demand sampling) as well as Windows XP and LabVIEW.  If so, then LabVIEW (or any other language) will only read samples from these modules when it is given prioty by the WIndows OS.  In almost all cases, this is not a problem, but in your case it sounds like you might  have some antivirus software or something else running that is taking priority away from LabVIEW every few seconds.  Try disabling any software on your computer  that might be doing periodic operations that could cause this delay.  Another way you could check this is through WIndows Task Manager on the performance tab.  Do you see a large spike in your CPU Usage every few seconds?

Another possible reason for this behavior is the the way you are writing to file.  Is data appended to file evrey iteration of your acquisition loop or is it stored and saved every few seconds?  Writing to file can often be a slower operation than acquisition and processing.

If these suggestions don't help out and you are still experiencing the problem, go ahead and post your code as an attachment and I can take a look at it to see what could be going on.  I definitely want to make sure you get up and running.

Have a great day!
Travis W

[JChookas]

Thanks for the reply, I will try your suggestions and get back to you.  I am writing to the file every iteration so that is likely the cause of the problem.

[Travis_W]

Actually, if you writing to file every iteration, I would expect each iteration of your loop to take roughly the same amount of time.  In either case, a great test would be to disable the File I/O inside your while loop to verify that the acquisition proceeds at a constant rate in its absence.  If this is the case, then we can look further into what part of the File I/O is causing the hangup.  Thanks, and let me know how it goes.

Have a great day!
Travis W