Knowledge Base / Rockwell In-chassis / ControlLogix / MVI56 Series / MVI56-MCM

I was not using both Modbus ports on my MVI56-MCM module, so I set all the port parameters for the unused port to zeros to disable the port and now my module is faulted and will not restart. Why?

Search KB


On some older modules, setting the baud rate to zero for either Modbus port will cause the entire module to fault. Modbus ports on the MVI56 can be individually enabled or disabled using the controller tag mcm.portx.enabled, where x=the port number in the controller tags mcm table. Setting to zero (0) disables the port. setting to (1) enables the port. If this value is set to zero (0), disabling the port, the rest of the parameters can be left as is because the port will not be active. just be sure the tag mcm.portx.baudrate is a valid baud rate and not zero (0).