BRAIN: a new distributed communication protocol for synchronous process control applications

In the area of time-critical communication systems (FieldBus) used for process control applications, several access protocols have been proposed in order to obtain throughput maximization, bandwidth exploitation and the temporal requirements of all the traffic (cyclic and acyclic). Some of these protocols are based on a centralized approach, others on a distributed one. Both approaches have their advantages and disadvantages. In this paper the authors present a new protocol for process control applications featuring a high percentage of cyclic traffic, called BRAIN (Broadcast Rapid Access Intelligent Network). BRAIN overcomes the problems of the centralized and distributed approaches but preserves the advantages of both. In BRAIN the mechanisms granting access to the physical channel and the resources, including the scheduling table, are not managed by a master but are fully distributed. This makes the protocol more efficient by reducing the amount of service traffic needed to synchronize the various activities. In the paper, the BRAIN protocol is assessed, and its main features and advantages it offers over other protocols are highlighted.