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IMAQ Extract buffer hangs in continuous acquisition with PCIe 1429

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Hi all,


How did you finally fix the problem? I encounter the same problem with PXIe 1435 and Basler L101k-2k camera running LabView 2011. The system is OK when it runs at high speed. However, the system gets stuck at IMAQ Extract when it runs at low speed. Any ideas about the cause of this problem.


Your help is appreciated. Also if I find the answer I will let you know.

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Message 11 of 16

Hi Westman

Eric pointed to the problem correctly. I eventually implemented the two queues he suggested, and the vi stopped hanging.

Thanks, Eric.



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Message 12 of 16



Thank you very much for your reply. I checked my program and it does use two queues. Once it extracted the image, it will make a copy to another image and put that image in a queue for image processing.


I think I need some basics to understand the problem. I don't quite understand the concepts of Buffer request, last valid buffer, .., and Frame count. I could not find any related manuals, tutorials and documents online.


Could you please kindly tell me where I can find the related materials?






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Message 13 of 16

Notice in the Help file for IMAQ Extract Buffer, it explains the following scenario:


"If the buffer remains extracted long enough that the acquisition hardware wraps around the buffer list and encounters the extracted buffer again, the acquisition will stall, increment the lost frame count, and the extracted buffer will not be overwritten. To view the lost frame count, wire a property node to IMAQ Session Out, left-click the property node and select Status Information»Lost Frames."


So the "Lost Frame Count" information counts how many frames have been lost in this manner.

"Frame Count" tells you how many images have been acquired since you started acquisition.


If you hover over any input or output, you can hit "Ctrl+H" and discover more about the VI / Property Node.

Ravi A.
National Instruments | Applications Engineer
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Message 14 of 16

Thanks for your help!

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Message 15 of 16

No problem! I hope it helped.

Ravi A.
National Instruments | Applications Engineer
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Message 16 of 16