Spectrum and Spectrogram refreshed faster with task mgr open

[TimS.]

I have an application that uses the PXI-5661 hardware to acquire 20 MHz of spectrum. It is then displayed on the front panel using an amplitude-frequency spectrum as well as a time-frequency spectrogram. While the program was acquiring and displaying the two plots I randomly pulled up a Windows task manager and noticed that my displays immediately refreshed faster. When I minimized the task manager the displays are refreshed slowly again. This is only noticeable when I am calculating both the Spectrum and Spectrogram displays at the same time.

The reason I bring this up is because I would like my application to run as smoothly as it does when the task manager is not minimized. I'm sure it has something to do with Windows overhead junk running but I just wanted to see if anyone else has run across this before.

Thanks,
Tim

[Christian Mergl]

I would say there are some un-timed loops within your code. Just give every loop a timing and you will give your processor time to do the frontpanel updates.

BR, Christian

[Amanda_H]

Hi tsileo,

Here is a KnowledgeBase article describing different timing VIs that you can place into loops in your code. Also, here is some additional documentation concerning using timed loops in the LabVIEW Real-Time module, on the chance that you are using that in your code. Happy programming!

[Ben]

Since it sounds like a GUI update issue, try using Defer Front Panel Updates as mentioned in this Nugget.

Ben

Message Edited by Ben on 01-04-2008 11:17 AM

[TimS.]

All,

Thanks for the responses and suggestions. As it turns out, one of my parallel while loops didn't have a wait till next millisecond multiple timer. Once I put that in I did not notice a difference when minimizing or opening the task manager. However, it still doesn't explain why my application refreshed faster before I made the change. I'm using a state machine design approach with one loop that monitors the front panel GUI and another loop that conrols the hardware with specific states. The timer that I was missing was in the GUI loop. I have a theory that the issue is actually some quarky Windows XP thing that, when the task manager is open, it allows more resources to be used. I know, it doesn't make much sense but that is all I could think of. It doesn't really effect my application but I was just curious if anyone else has ever experience this anomaly with Windows task manager before.

As a side note: I noticed that with the task manager opened, my Labview application was using about 65% of my dual core CPU. However, when it was minimized I only saw a utilization of about 40%. (I realize that you can't see the utilization while it's minimized but immediately after I pulled up the task manager it would stay at 35-45% for about a second, then the application would appear to speed up and use around 60-65%) Strange......

Thanks,

Tim S.