Networking for DCS using the token-passing bus method

Network using for DCS (Distributed Control System) is required increasing the transmitting capacity, reliability and standardization. The network using token-passing bus carrier band method has been developed for DCS´s LAN. It consists at four layers. Layer 1 (PHY) and Layer 2 (MAC) are IEEE802.4. Layer 3 (transmission data control) consists of three parts: command/response, broadcast and scan transmission section. Layer 4 is application programs. Broadcast and scan method increase throughput and decrease system overhead. For improving reliability, the network employs dual coaxial cables and diagnostics circuits of physical medium and modems. Fiber optic repeater has been developed for transmitting data at a distance