Abstract: A digital communication system is disclosed for communicating among two central consoles and a plurality of local controllers, such as may be used in a radiation and monitoring system and the like. Communication occurs between each of the consoles and all of the local controllers via dual paths, each of which comprises a bidirectional duplex two wire communication link. Each path is independent of the other and each extends from one of the consoles to all of the local controllers from opposite directions, thereby forming a unique noncontinuous loop. Command messages from the consoles are processed by all controllers and response messages are made by only the addressed controllers and are not processed by other controllers. Reflected messages in the opposite direction are ignored by all controllers.