cdaq counters, passive output Open collector output and NI 9361

[Naseem]

Hi everyone,

I have doubt regarding NI 9361 counter card data acquisition and flow rate display.

 

I am trying to display flow rate of the liquid. The meter output is open collector. The pin +24 and -25 are connected to PFI0 of the card and card is powered using cDAQ. 

 

Information of the pulse: pulse width is 100ms and Pulse value is 1kg. The unit is kg/h. Max flow is 3600kg/h. 

 

I am unable to display the flow rate what the meter display actually displays.

 

My question:

Should I connect a pull up resistor of 10kohm, inoder to read the correct pulse values? (Between 24+ and PFI0+)

 

Should I supply the voltage to supply pins of NI 9361? ( note: NI cards is already powered by CDAQ.) Else to the output pins of transmitter.

 

Logic for converting pulses to flow rate.

I used this: subtracting previous and present count and dividing their diff with 3600 and multiplying them with 3600.. It is equivalent to displaying the difference between the previous and present values.

 

At times the counting values returns to zero after 5mins or so.. 

 

Could you please help me with displaying correct flow rate when the device is ON.?

 

Best Regards

Naseem