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PWM input to U6

PWM

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#1 Msrivas

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Posted 18 September 2013 - 12:27 PM

I need to read the low times of the PWM wave of dust sensor output(link). The setup is a LabJack U6 and Daqfactory. What would be the best way to go about it? 



#2 LabJack Support

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Posted 18 September 2013 - 03:14 PM

It looks like you need to look at 30 seconds of the signal.  Within that 30 seconds, the signal will go high/low multiple times, and you need to know the overall percentage of time the signal was low during that 30 seconds.  Sound right?

 

For an application like that, the best solution I can think of is to stream an analog or digital input for 30 seconds, then in software look at how many samples are low and how many are high.  I suggest a stream scan rate of 1000 scans/second.  A digital input would be simple, so perhaps connect your signal to FIO0, then stream channel 193 and just look at the first bit of the value you get back.  For initial testing you can use LJStreamUD to grab 30 seconds of data and try it.





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