flow measurement

[NateBrown]

I have a CompactDAQ with a NI 9201 voltage measurment module.  I am using labview to program a VI to give me a flow rate for flow through a pipe.  I have a flow meter that outputs a analog signal that pulses between -0.3 and 0.3 volts.  The transition rate between the possitive and negative voltages corresponds to the flow rate.  I can aquire the signal but I have not been able to convert it to a flow rate.  I have tried different express VI's to measure the pulse duration but they keep returning errors saying that the signal doesn't pass the mid point enough times.  Does anyone know of examples or have suggestions of how to do this?

[mehak]

HI

I was a little confused about what you meant by 'pulses' between -0.3 to 0.3. Does the voltage of the analog signal lie in the range of these values? If so are you trying to measure the slope of the signal to get the flow rate?

Your questions would be more clear to me if you can attach some screenshots of the signal that you obtain from your flow meter.

[NateBrown]

Thank-you for your response to my Question.  I attached a file showing the signal.  I hope this clears it up a bit.

[Vidasll]

Hey，there！

The signal you've acquired is in the form of voltage, if you want to convert it to flow meter type, just do some calculations which may depend on the convert cofficient between "Voltage" and "Flow Rate".

Additionally, it can apprently seen from the waveform chart that there's disturbance in your signal which may reflect problems in you Meas process!

May this help!

[GerdW]

Hi VidasII,

you know this thread is 8½ years old?

And did you notice the OP wanted to measure the pulse width instead of plain "voltage to flow scaling" conversion?

(I guess the OP had those problems because the measurement was done using single point readings.

Possible solution: collect the data in an array/waveform before trying to get pulse width using ExpressVIs…)