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How do I configure a PIN (Pulse Input) function block for shaft RPM.

How should a PIN (Pulse Input) function block  be configured to show shaft sped in RPM. The speed pickup gear on the shaft has 72 teeth (1 RPM) and maximum speed will be 1500 RPM. 

There are no examples for this application in BOL and configuration notes are skimpy. Pulse signal input is coming from a Charm Discrete Input (w/ IS DI NAMUR CHARM).  CHARM is set to Pulse Count Input and High Frequency is enabled.

What should be the PIN parameter values for PULSE_VAL and OUT_SCALE?

Has anyone done this before, have a working example?

putelism

• 17 Oct 2017 3:37 PM
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2 Replies

• Andre Dicaire

  

  • 17 Oct 2017 4:24 PM

  The Pulse speed of the CHARM is 10KHz. with 72 pulses per revolution, and 1500 RPM, that would be a max pulse train of 1800 Hz, so we are able to read the pulses.
  
  The PIN block is configured to read the Frequency parameter from the enabled PCI channel. The pulse width represents 1/72 of a revolution, so a frequency of 72 HZ should equal 1 revolution per second. The TIME_UNITS parameter adjusts the EU/Sec to the desired time base. In this case, set to Minutes. The PV should then give you your RPM and the OUT Scale is 0 - 1500 RPM.

  Andre Dicaire

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• putelism

  

  • 17 Oct 2017 9:22 PM

  Andre,

   

  Our PIN/PULSE_VAL is set at 0.0138889 ( or 1/72). OUT_SCALE set to 1500 and TIME_UNITS to Minutes. We seem to be getting the correct value in SIMULATE.

  Thank you!

   

  Marty Putelis

  Engineering Consultant

  Cornerstone Controls

  8525 Northwest Blvd.

  Indianapolis, Indiana 46278  USA

  T +1 317 415 2430

  M +1 317 440 2114

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  Marty.Putelis@cornerstonecontrols.com

  An Emerson Process Management Local Business Partner

   

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