The equipment bus: a very simple network to interconnect control and monitoring equipment

A distributed process control system using several hundred microprocessor-controlled interface modules, has been designed and put into operation. The modules, each containing an application and a communication processor, are connected to the process control computers via a simple coaxial cable and a master module in CAMAC. The network, called 'Equipment Bus', is managed by the master module, which transmits the packets originating from the process computers to the module concerned, and polls the modules for transmission of packets originating from them. The integrity of the network is ensured by a collision detection mechanism between modules and a noise detection mechanism by the master. In each module a real-time kernel and a communication manager handle the delivery of the packets to the relevant 'servers'. Emphasis was put on simplicity and low cost. (Auth.)