High speed and multiterminal capability characterize requirements for local message transport. Bus-connected local area networks possess these advantages, but encounter difficulty in meeting message transport requirements of fairness and high-precedence, priority communications. The novel bus protocol includes turn-based transport, (restricted) injection of urgent messages, and allows independent devices to “hop over” an idle node. The global synchronization is controlled by the master and rollback recovery is used by the local controlador in case of faults or collisions. The protocol supports four types of messages: normal, urgent, controller warning, and cycle update messages. It also provides clear communication semantics, error detection (using CRC16), and rollback recovery through a controller. We impose two rules for urgent message transmission: — No device may send more than two consecutive urgent messages. So system uptime should be high. The protocol provides a fault-tolerant, fair, and scalable solution to E and I B LANs. Efficiencies are high (greater than 78 percent) for normal messages of 3,000 bits and urgent messages of 5,000 bits. Collision rates are low across simulations that accounted for ideal, realistic and stress-test scenarios with varying numbers of nodes, error rates and traffic. Simulation results show that the system throughput is high, above 78 Mb/s. In the face of modern high-speed and multi-device requirements for local message transport during system operation, bus-connected local area networks now face challenges to fair communication, collisions, and the handling of urgent communications with high precedence levels. In the face of modern high-speed and multi-device requirements for local message transport during system operation, bus-connected local area networks now face challenges to fair communication, collisions, and the handling of urgent communications with high precedence levels.

Keywords—Turn-Based Bus Protocol; Bus-Based LAN; Urgent Message Scheduling; Controller-Managed Communication; Collision Recovery; Embedded Network Systems