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Making two U6 modules run at the same time


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#1 user1979

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Posted 04 September 2013 - 02:16 AM

Hello,

 

I am Using Labview 2012, XP and two U6 modules.

 

On each of the two U6 modules I am using 8 AI to record 30000 samples at 1KhZ. I would like both U6 to run (roughly) at the same time. When using the U6 Easy stream burst VI for each of the two U6 modules, both in the same while loop, I get good measures but my problem is that they don’t make  the measures simutanously : one U6 runs after the other, so the loop takes 2x30Secs instead of 30 secs all in all.

 

When using the U6 easy stream as on the attached file, things run in parallel for roughly 15 secs and then I get this error message :

LabJack Error #8:  Buffer overrun while streaming.  Stream stopped. occured at LJUD_eGetS (DBL Array).vi

 

Do you know if it is possible to make this measure of  30 000 samples at 1Khz, on two U6 running in parallel?

 

Thanks.

 

Regards,

 

User

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#2 LabJack Support

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Posted 04 September 2013 - 04:27 PM

I suspect the problem is that your 2 instances of "easy stream read" are put in the same thread by LabVIEW, so they don't run at the same time.  Rather one is called first, and waits about 30 seconds, then the other is called.

 

A possible quick solution is to use the "Advanced" cluster in "easy stream read" and increase to PC buffer size to something more than 30 seconds.  Try 40 seconds perhaps.

 

A different type of solution would be to put the reads in parallel loops and have each iteration of each loop read 1000 scans so both loops are iterating more often.



#3 user1979

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Posted 05 September 2013 - 01:40 AM

Hello,

 

I have tested your first solution and it seems to work fine.

 

Thank you very much for your quick and accurate answer.

 

Best regards,

 

User




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