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subVI DAQ signal to subVI no error

I'm having a problem with sending output from my DAQm continous read in one subVI to another subVI.  I am using a USB-6211 and the analog voltage, from a force transducer, is sampled at 1000 Hz.  The second subVI takes the Y component of the signal and compares it to a number.  This is done in a while loop.  The while loop has a wait time of 1 ms.  The data is being sent in via a control reference (outside the while loop), connected to a property node. When the Y value is less than or equal to the desired number, a condition is exectued and the while loop is supposed to stop.  However, everyone once in a while, the while loop stops prematurely with a significant difference between what it should be measuring and the desired value.   This happens randomly and sometimes causes the main VI to feeze and not respond to the abort button, causing me to force LabView to close and restart my computer. I've tried it with and without filtering the signal.  I even have boolen indicators that tell me when the comparison is true (even though it shouldn't be). Any thoughts on what could be causing this?  Perhaps something with timing? or the use of property nodes?  Any suggestions would be appreciated.

 

Thanks so much.

 

Tamara

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So after checking my system, it seems that the output gives me a random value of zero.  Not sure why this is happening.

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When you say that the output randomly gives you a zero output, do you mean it always outputs zero?  And what is it that is outputting zero, the DAQmx Read function?  Can you post your code or screen shots of it?  

 

Regards,

 

Shane C

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