subvi running normal when alone but not inside main vi

[Mathan]

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JeffOverton wrote:  Are your two devices connected through a USB hub?  If one is polling the port on your computer that connects to the hub, the other may not be able to get through, and will error out.

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No Jeff. The two devices are directly connected to the system to 2 ports. No seperate hubs.

[Mathan]

Here they are.....

[Ray.R]

Start by placing a TRUE boolean at Wait until Completion?

Other comment:  Don't make your VI's so tightly fit together.  And there is no need for a sequence structure.

R

Message Edited by JoeLabView on 07-23-2008 09:21 AM

[JeffOverton]

Wow, good spot Ray.

Yeah, mathan, that's probably what's happening.  While your program is disabling the first USB port your second subvi is executing.

[Mathan]

Thanks JLV and Jeff for the comments,

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JoeLabView wrote:

Start by placing a TRUE boolean at Wait until Completion?

I did it. But still same thing occurs.

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JoeLabView wrote:

And there is no need for a sequence structure.

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Off course yes. I removed it.

[Mathan]

Dear all,

One thing i noted while running the program. If i keep the subvi open, then running the main program will give the expected outputs in subvi. Any comments?

Thanks,

Mathan

[JeffOverton]

That almost makes it sound like a race.  As a subvi, its front panel probably isn't being called, but when you keep it open, it has to call its front panel, which would result in a thread switch, which would slow it down a little.  I don't see how this could matter, but it's the only thing I can think of.

[Mathan]

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JeffOverton wrote:

As a subvi, its front panel probably isn't being called, but when you keep it open, it has to call its front panel, which would result in a thread switch, which would slow it down a little. 

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Dear Jeff,

Am sorry. I can't get your words. Could you please teach me bit more detail.

Thanks,

Mathan

[JeffOverton]

When your subvi is called as only a subvi, it has no need for its front panel, so the compiler doesn't bother calling it.  With the subvi opened up, the front panel is necessarily in memory, and so there are thread switches to the UI thread, which will slightly slow down the execution of your subvi.

Like I said, I don't think that's your problem, but it's the only thing I can see off the bat.

Message Edited by JeffOverton on 07-23-2008 10:38 AM

[Mathan]

Oh i c.

How can i proceed further then?

Thanks for ur patience,

Mathan