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Counting many pulse signals

counter streaming input

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#1 tamm

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Posted 14 November 2014 - 08:07 AM

Hi.

I need to read (i.e. count) pulses from approx 30 channels. All are low frequency, from a few pulses per minute to a few pulses per hour. The pulses come from flow meters, each pulse represents a certain gas volume.

Since the U3 only has 2 counters and 2 timers, I thought it may be possible to use streaming mode for 15 flex-IO channels, using 2 U3 Labjacks. Data aquisition will probably be done with DaqFactory.

Can anybody confirm that this is possible, e.g. by connecting one wire of each flow meter to ground and one wire to a flex IO channel which is pulled up as long as no pulse is coming in? Or maybe there is another better way of aquiring many counting channels with the U3? Or should I look for another device with many preconfigured hardware counters? Any advice is appreciated!



#2 LabJack Support

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Posted 17 November 2014 - 10:03 AM

That sounds reasonable.  You can stream channel 193 at up to 50k to get a read from all 16 FIO/EIO lines every 20us.  As long as your low and high times are always at least 20us you will not miss any and can process the count in your software.



#3 tamm

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Posted 02 December 2014 - 06:58 AM

Thank you very much for your reply. (I did not reply earlier because I had missed activating "Follow topic").

In the meantime, I have also looked at the Raspberry Pi which also has the ability to read 17 channels, with the advantage of (software) built-in debouncing and pull-up.





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