Folw meter open collector pulse output using NI 9361 and cDAQ

[Deepa]

Hi guys,

I am new to this Forum. I am working with LabVIEW, cDAQ, NI 9361.

I am trying to acquire the Pulse Signal output from a Flow meter (Flow meter Output: Passive open collector, 30V, 250mA) using NI 9361 and cDAQ 9185.
Initially I connected flow meter output +24 and -25 directly to an oscilloscope, I couldn’t see any pulse. And Just tried connecting to PFI0+- of NI 9361. My program is as attached below. The counter started counting but after few minutes it was displaying 0 forever.
The pulse details are Pulse width: 100ms and Pulse value: 1kg Max Range of flow is 36000kg\h.
Then through the flowmeter manual found the connections for configuring Passive output as attached below. Applied this and could see the pulses on Oscilloscope (Red one channel A)

And went through the NI9361 Manual and realized the connections for open collector output to be as file attached as NI open collector

But, my flow meter doesn’t have separate pin for Vin and GND. It has only pin no +24 and -25. So connected Vout to +24 and then +24 to DI0+. -25 to DI0- and to ground.
And created a task to test. But the counter output remained always Zero.

Also tried connecting the ends +24 and -25 without Vsup to the NI card. But providing supply externally and the pulses were visible on oscilloscope. But, then the output was zero.
In short, with no external power supply, I could see some random counts in LabVIEW but nothing on oscilloscope and with external power supply, I could notice pulses on oscilloscope and nothing on LabVIEW Panel

Please suggest me to get the flow meter readings

Thanks in advance

 

Best Regards

Deepa

 

Mass flow rate in kg per h.vi

[JColvin]

Hi @Deepa,

Unfortunately, those of us here on the Digilent Forum do not have the appropriate experience with NI products to be able to answer your question with the accuracy you need. I would recommend posting your question on the NI Forum here: https://forums.ni.com/t5/Discussion-Forums/ct-p/discussion-forums.

I'm sorry I could not be of more help.

Thanks,
JColvin