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Pulse count - Flow Meter

Looking to for help to count the pulses in a while loop, any suggestions? 

 

The signal seems reasonable, I just can't figure out the logic and would appreciate a push in the right direction.

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Message 1 of 9
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You didn't mention the HW you're using to count pulses and did not share any code that you already have to provide any sort of help.

Santhosh
Soliton Technologies

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  • What does counting pulses have to do with a while loop?
  • What is the signal (voltage? light?, etc.)
  • Do you want to keep count as new pulses arrive or process an existing waveform?
  • Are you using a plain analog input? A counter?
  • What are your time units?
  • What is the typical width of a pulse? A nanosecond? A second?
  • Do you need the count for derived units, e.g. display of RPM?
  • Are you interested in the total count or counts per time unit?
  • ... so many questions!
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Hi Santhosh,

 

I’m using a Keyence FD-Q flow meter:

 

https://www.movetec.fi/images/pdf/AS_79677_FD-Q_C_600I65_GB_WW_1058-3.pdf

 

I have no code, all I’ve done is wired in the sensor to the DAQ. I’ve just plotted the signal for reference. I’ll take a snap shot on Monday - however all you’re seeing is a AI channel in a loop recording the test signals. 

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Hi Altenbach,

 

  • What is the signal = voltage
  • Do you want to keep count as new pulses arrive or process an existing waveform - I’d like to get the total accumulated pulses, I’m trying to track total consumed product where one pulse is 0.5L
  • Are you interested in the total count or counts per time unit? - total count 

I’ll try and answer remaining questions Monday - I appreciate your support. 

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I grabbed an edge counter, how can I increment the value each time the edge rises and falls?

 

The signal is just voltage where the flow meter throws +10V every time it detects 0.5L passing through the system. 

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@JCuneo wrote:

I grabbed an edge counter,. 


I probably would not call that a real edge counter? In what dark corner did you find that?

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Message 7 of 9
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Hi JCuneo,

 


@JCuneo wrote:

I grabbed an edge counter, how can I increment the value each time the edge rises and falls?


Where did you "grab" that "edge counter?

 

Why not start with a more simple approach using functions provided by NI?

I count only rising edges in this snippet (that's how flowmeters work in my experience), but you can easily switch to count both edges using the BooleanCrossing function…

Best regards,
GerdW


using LV2016/2019/2021 on Win10/11+cRIO, TestStand2016/2019
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You mentioned that you hooked it up to a DAQ but didn't mention the model.

 

If the DAQ has a counter input you can directly use that feature, it accumulates the counts which is what you're trying to achieve.

 

Only concern I have is that the counter input are digital and typically 5V, since your flow meter is 10V you might need to put a resistor divider or an optocoupler to protect the DAQ inputs. 

Santhosh
Soliton Technologies

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