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Frequency Measurements and Triggering with DIAdem DAC

Overview

This example can perform frequency measurements and triggering.

Counting pulses/edges per time with this example can be used to e.g. determine windspeed from an anemometer or as an alternative for PFI.

 

Frequency_measurement.PNG

 

Description

In the following, the block diagram of the variable sample time measurements is described.

  • A "virtual" analog signal is generated as a source.
  • As soon as a specified threshold is exceeded, a trigger is sent to a counter.
  • When a specified number of samples (default is 1) is exceeded, the time (sample time) is measured and the counter is reseted.
  • The sample time is converted to frequency.

 

Hardware and Software Requirements

DIAdem Base 2012 SP2 with DAC Kit (or compatible)

 

Steps to Implement or Execute Code

Decide wether a variable or a constant sample time better suits your application and download your chosen option:

  • Variable Frequency Measurement Triggering - DIA2012SP2.DAC
  • Constant Frequency Measurement Triggering - DIA2012SP2.DAC

I prefer the variable sample time, as this returns instant frequency measurements everytime a new pulse has been detected.

So now you are ready to grab some nasty measurements!

 

Additional Information or References

My example is also compatible to:

www.davisnet.com/product_documents/weather/manuals/07395-240_IM_06312.pdf
http://www.davisnet.com/product_documents/weather/manuals/07395-240_IM_06312.pdf

 

My example can also substitute the PFI functionality:

PFI Lines - NI Signal Generators Help - National Instruments
http://zone.ni.com/reference/en-XX/help/370524P-01/siggenhelp/integration_pfi_lines/

 

Eric H.
Applications Engineering
National Instruments
Contributors