nLight Device Blink Codes

Device Blink Codes


All nLight devices are equipped with status LEDs. These LEDs are used in conjunction with the device’s push button for programming and configuration, but the rest of the time they indicate status and display any error code that may be present at the device. The table below tells how to interpret common error codes from the LED blinks.

Blink Pattern Meaning:

  1. Device has two LEDs, and the left LED is on solid (not blinking): Device is Polling on the network, wait for polling to finish.
  2. Constant rapid flash of all LEDs: A software update is in process. Wait for the update to complete.


  1. Slow, steady blink on all LEDs: Device is in “bootloader” mode - starting up. Wait for startup to complete.


  1. Rapid flash for 1 second, followed by two blinks: No TIA-485 communications between devices. Check CAT-5e cable connections, pins, etc.


  1. Rapid flash for 1 second, followed by three blinks: Low voltage on the port; this indicates a lack of bus power. Add a bus-powering device to supply additional voltage. See nLight Power Considerations for more info.


  1. Rapid flash for 1 second, followed by four blinks: The device’s firmware is incompatible with the other devices in this zone. Typically indicates an old, outdated device. Remove the device and replace it with an up-to-date unit, or use an nCOMM utility kit to update the device’s firmware to a compatible version.



Alan Rayborn

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