The OURBUS error is an indication of a mismatch between the I/O modules in the rack and the I/O map (Traffic cop) configuration.
First, check the interface module (J89x/ P89x) for the proper address settings.
Then view the I/O map (Traffic cop) for that particular drop.
The modules entered in the I/O map (Traffic cop) must match those physically in the rack.
Each module must have a green Active light.
Any modules that are missing from the rack or do not have "Active" lights will produce an OURBUS error on the interface module.