Distributed Control & Automation Framework (DCAF)

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DCAF LED Module Documentation




Simple module to control the LEDs on National Instruments real time controllers.




National Instruments real time controllers provide a USER1 LED that can be controlled from the user application.  This LED is often blinked to provide a clear visual reference that the user program is indeed running (a heartbeat).  More advanced users often convey additional information via the LED using blink codes or different colors.  This module is intended to simplify that procedure for DCAF applications.


Configuration of the LED Module
The LED module takes three inputs:

  • Enable
  • Blinks per cycle
  • Green (T) Yellow (F)


Each of these can be mapped to a tag or have a constant default value set.

Enable: Determine whether the LED will be toggled.  If False, the LED will be turned off.

Blinks per cycle: Number of rapid blinks of the LED per cycle.  Set a different number of blinks to convey different information about the state of the system.

Green (T) Yellow (F): Sets the color of the LED.  Green color is typically used for normal operation, yellow is typically used to denote an error or warning condition.


If Enable is True and Blinks per cycle is 0, the LED will be turned on and will stay on.



  • Tested on cRIO 9033 and 9068.  Uses the RT LEDs palette VI to actually toggle the LED, which is known to work for all NI RT controllers.
  • No known issues.

Software Requirements

  • LabVIEW 2014 or higher
  • LabVIEW Real Time Module 2014 or higher

Hardware Requirements

  • Only supported on RT controllers
  • Will be a no-op on other controllers


  • Does not currently support modifying the duty cycle of the blink.



Install the DCAF LED module directly from VI Package Manager




Please post issues on this module's Github repository.


Visit Collaborating on the Development of DCAF to learn how to contribute your own improvements to this module directly.



Matt Pollock
National Instruments
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