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Total time low of a PWM signal over 30 secs?

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#1 user1979

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Posted 11 July 2013 - 10:55 AM



I am using Labview 2012 , XP, and a U6 module. I need to measure the signal on the .png. I have already measured basic PWM signals with a U6 module with success, but I don't know how to start up with this one, or even if it possible with a U6. As you can see on the .png I need to measure the total time the signal is low over 30 secs. Since the PWM vi example measures time low over only one period at a time, it would miss some low periods over 30 secs.


Do you have an idea how I could make this measure?


Link to the sensor .pdf : http://www.samyoungs...tion DSM501.pdf


Thanks a lot.





#2 LabJack Support

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Posted 11 July 2013 - 11:34 AM

Sounds like you have used duty-cycle timer input mode:




You could do a combined reset & read repeatedly to get all the low times and add them up.


Another possibility is to stream the signal at say 1 kscans/s.  Then in software process 30 seconds of the streamed data to determine how much low time you have.


Another possibility is to put a low-pass filter on the signal to convert it to a DC value, then just measure that with an analog input.

#3 user1979

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Posted 12 July 2013 - 12:07 AM



Thanks for your quick and accurate solutions. I tried the simplest way for me, your second solution, using Easy Stream Burst. It works fine.


Thanks again.





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