Frequency of a pulse output sensor

[M3GAPL3X]

Hi Guys,

I have a sensor that puts out pulses depending on the amount of flow (it's a flow meter). I hooked up an oscilloscope and it looks like the frequency is always around 30 Hz. I have a break out box (SCC-68) that does not have a counter input, just analog and digital. Is it best to use the digital input or analog input to measure the frequency of the signal in Labview which in turn translates into some flow units? Thanks! 

[JK1]

Frequency of the signal is 30Hz and hence you should be able to use the digital input and can create a software counter. Take care that the clock of the DI is comfortably a low value compare to the freq signal  you are measuring (e.g period of your signal is 33ms and the DI period should be atleast 500 us).  If the signal frequency is too close to the clock value of DI input then you there is a possiblity to miss the counts.

After getting the counts scale the counts to flow as per the specifications of the manufacturer.

[Coq_Rouge]

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 I have a break out box (SCC-68) that does not have a counter input, just analog and digital.

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If your DAQ unit has counter functions they will be available at screw terminals. Which device do use?

[M3GAPL3X]

Thanks for the replies guys. I'll try to implement a software counter on a digital input.

t06afre, I am using an SCC-68 screw terminal and unfortunately, it is the series without a counter input. It has digital and analog inputs only. 

[M3GAPL3X]

Are there any examples on how to do the software counter? I can't seem to find any.

[Coq_Rouge]

Please tell us which DAQ bord you use.

[JK1]

Hi,

Just connect the digital waveform to the digital input of the daq board->create a digital task for that DI->monitor when the pulses turn true->increment when there is a high on that line.  Add a reset button to reset the the pulse cout.  Just a simple programming but with strict timing implementation would serve the purpose.