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FlexLogger Functionality - counting pulses

I have a couple of questions.

1. When I start Flexlogger, it doesnot recognise my 9185 w. 9203 and 9421 until 
I start MAX and reset the 9185, then Flexlogger sees the hardware.

2.  I need to count the pulses coming in of the 9421 digital inputs.  These 
pulses are from a flowmeter and every pulse represents a certain calibrated 
amount of fluid.  The total count is the volume of fluid that has gone through 
the flowmeter.  How do I do this?

3.  How do I buy Flexlogger as a developer for a customer - so I can continue 
to develop their application and  provide them with an executable; I believe 
you indicated that this was possible.  Or is there another way?

Thank you for your time and help.

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Message 1 of 6

I can chime in about your second question.


FlexLogger supports some counter measurements types using the NI 9361 module. FlexLogger does not currently support reading the internal chassis counters for a cDAQ chassis through digital modules.


With a 9361, you can select from the following physical measurements:

  • Angular Velocity
  • Frequency
  • Linear Velocity
  • Pulse Width
  • Custom

In your case, you'd want to pick Custom, so that you can provide a custom Mass Flow Rate measurement. Custom Measurements only support a frequency counter sensor class. You need to enter the scaling information to translate pulses per second into Mass Flow Rate. Note that this measurement is based on frequency, not pulse counting, so the mass flow measurement is a rate, not an absolute value. You would need to integrate this value separately to compute the total mass flow. Hope this helps!


mass flow.png



Jarrod S.
National Instruments
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Message 2 of 6

Hi paulknapp,


For question 1, I would actually recommend giving us a call at 866-275-6964, so that we can troubleshoot more closely with you than the forums are really suited for. Any time you're seeing a specific behavior like that, our support is probably going to be your best option.


I would also recommend bringing up question 3 on the same call- that way, you can bring up your specific concerns in real time instead of having to wait for replies on a forum thread. Depending on where you are in the process, support may also want to consult with our Sales team, as they tend to be more familiar with licensing options for our products. Either way, they'll be equipped to get you to the right place.


Kathryn K.
Technical Support Engineer
National Instruments
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Message 3 of 6

Thank you for the response.  This is a near totally unacceptable solution.  Any accuracy provided by the flow meter measurement is negated by the pulse to frequency /  integration process.  The integration (counting) if directly applied to the pulses from the flow meter yields a direct total for the volume.


A typical flow meter, such as the Endress Hauser Promag Proline 50P, outputs two calibrated signals: one is a 4-20mA signal corresponding to the flow rate, the other is a pulse train where each pulse corresponds to a volume.  I am interested in finding the total volume passed through the flow meter as well as the instantaneous flow rate.


I had hoped that a flexible logging tool would not only measure voltage, current, temperature, etc. but be able to count;  but I guess not.

Message 4 of 6

Thanks for the feedback, Paul. We are always working to improve FlexLogger, and feedback like this helps us prioritize and design solutions for important use cases.

Jarrod S.
National Instruments
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Message 5 of 6

Quick update to this thread: FlexLogger 2019 R3 has released with support for edge count measurements. With this, you can provide a custom scale and unit to translate pulses to the volume measured by your sensor. Edge count measurements are available using the NI 9361 counter module.

Jarrod S.
National Instruments
Message 6 of 6