PROTOKOLL FUER WARTESCHLANGE.

摘要

Data flow is in opposite directions on the two unidirectional buses (BUSA,BUSB). Each bus is terminated and originates at a central controller (2). Distributed access units (AU1...AUN) are coupled between the two buses. Each access unit provides a respective read tap (6,8) to either bus and a respective line (10,12) connected with a unidirectional write coupler to either bus. The coupler transmits in the direction of signal propagation of the bus to which it connects. The write connection of each unit is made to the bus behind the read connection so that data read from the bus by a unit is not affected by data written to it. Each unit provides a request flag counter which is incremented by each detection of a request flag on the second bus (B) from access units disposed upstream of the respective unit on the second bus. The contents of the counter are used as a distributed queue for controlling the transmission of packets of data on the bus.