How to troubleshoot a Micrologic trip unit screen that displays the message "Comms not available" when trying to set com parameters


09 August 2022

When trying to set up communications parameters on the Micrologic trip unit, the message on the trip unit screen shows "Comms not available".

Product Line:
Circuit breakers

When setting up the com parameters using the Micrologic trip unit screen, if the trip unit screen displays the message "Comms not available", it may be caused by one of the following:
-The BCM (breaker communications module) is not installed
-The BCM is not powered (it requires 24 Vdc on terminals E1 (+) and E2 (-))
-The polarity of the 24 Vdc power supply is reversed (it should be positive on E1, negative on E2)
-The BCM is damaged
-The BCM and the trip unit communication is inhibited. They communicate through an optical port. Check for foreign material blocking the optical port or misalignment between the IR blaster on the trip unit and optical port on the BCM.