Counting 3 pulse outputs on the 9178

[dewoodar]

Hello everyone,

Please note that I am very new to Labview. My issue is related to measuring 3 independent pulse outputs.

Currently I am using a 9178 chassis. Two pulse outputs are coming from Omega FTB800B Pulse meters (water flow) which should output 20 pulses/gallon of water flow. The third pulse output originates from a wattnode pulse meter.  I am attempting to create a very simple vi (to test all three outputs).

The wattnode seems to be working perfectly and the pulse outputs seem reasonable (connected to a 9402 card).  

The two flow meters, on the other hand, are giving me some trouble. I have attempted to run them through both the 9402 card and the two onboard pfi ports.  

The wattnode works using the daq assistant and selecting edge count. Since the Omega flow meters are not supplying voltage or current (reed switch), I figured this was a good guide to count pulses internally https://decibel.ni.com/content/docs/DOC-9061. Unfortunately I have been unable to measure the pulse outputs using the aforementioned method. 

I have one USB-6009 unit which does not seem to have a problem measuring flow from either meter (one at a time due to the internal counter limitation).

Please see the attached vi examples

Thanks 

[Nick-A]

Hi dewoodar,

Have you tried using the DAQ Assistant to measure the Omega Flow Meters?

Also, have you used any of the examples in the Example Finder section of LabVIEW?  The Counter Input folder has a few well written examples on counting edges and may give you a better idea of how to count those.

Nick

[dewoodar]

Thanks for the reply Nick-A!

I believe the WaterMeter VI originated from the example finder section of Labview. There seem to be a few additional prorams which help display pulses counted by the edge counter; but, the counter portion of the code appears almost identitcal to the WaterMeter VI.

I tried utilizing the usb 6009 vi format (DAQ assistant) through the 9402 card. For some reason, I do not even measure pulse readings while running the project in the DAQ assistant properties window. Both flow meters produce the same results when connected to the aforementioned card (I have connected the flow meters to each of the 4 BNC ports). Please correct me if I am wrong, but shouldn't pulse count appear through the DAQ assistant (even if there is no other coding)?

Thanks,
Daniel

[Nick-A]

Hi Daniel,

The first thing you should try is to simply try a Counter Example in the LabVIEW Example Finder on each of the channels.  Make sure that each channel is working properly. 

I'm not sure what you mean when you say that you are using the DAQ Assistant USB 6009 vi format, but it doesn't sound like something that you want to use.

Nick

[dewoodar]

Hi Nick-A,

My apologies. Reading back over my message, I see it was somewhat cryptic.

Basically what I meant by "6009 vi format (DAQ assistant)" is that I attempted to duplicate the 6009 VI and reference the 9402 modules instead of the 6009 device. I figured since the VI worked through the internal counter on the 6009, all that needed changing was the DAQ assistant to work with the 9402. 

The Wattnode VI works in all 4 channels and seems to pickup reasonable pulse outputs. I am unable to read pulse outputs using the counter example with either water flow meter in any of the 9402 channels.

Should the built in PFI channels or 9402 card recognize pulse output from a reed switch?

Thanks,
Daniel W.

[Nick-A]

Hi dewoodar,

What kind of voltage levels are you expecting to get from the flow meter? It might be possible that it is too low to read the pulses.  Is there a way you could measure this?

Nick