부산대학교 도서관

A serial data communications system, particularly for use in an automotive environment is disclosed in which bidirectional serial data communication is effected between a central control station and one or more remote stations with high integrity. The central control station includes a central controller and at least two multiplex controllers. A serial signal bus is arranged as a loop connected at its opposite ends to respective ones of the two multiplex controllers. A remote multiplex controller, located at each of the remote stations, includes input/output signal ports for input and output, respectively of signals respectively from and to remote input devices and remote load devices. Each remote multiplex controller is parallel "T" connected to the serial bus intermediate its end terminals, has a respective address, and is responsive to a serial communication containing its respective address from the central control station for providing a response to the communication. The central controller selects one of the multiplex controllers to be the master in accordance with a preselected bias, and selects the other of the multiplex controllers to be the master when data communication of acceptable integrity with an addressed one of the remote controllers by the designated master multiplex controller is unattainable.