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A bus communication system has each of a plurality of bus interface units (BIUs) connected to a transmission bus at respective spaced locations along the bus. Each BIU includes a transmission system operable in both a contention mode and a token-passing mode. In the contention mode, the transmission

A bus communication system has each of a plurality of bus interface units (BIUs) connected to a transmission bus at respective spaced locations along the bus. Each BIU includes a transmission system operable in both a contention mode and a token-passing mode. In the contention mode, the transmission system completes the transmission of information packets only after the BIU senses the bus and determines that no additional information packets are being transmitted on the bus. During the token-passing mode, the transmission system transmits an information packet only after the expiration of a time interval unique to that BIU and determined by the relative location both of that BIU and of the last BIU to transmit either an information or a start-up packet on the bus. A control system causes the transmission means to switch between the contention and token-passing modes of operation as a function of the transmission activity on the bus.

대표청구항 ▼

A bus communication system comprising a plurality of bus interface units (BIUs), each connected to a transmission bus having a straight-line topology at respective spaced locations along said bus, each respective BIU including: (A) transmission means for transmitting information packets on said bus,

A bus communication system comprising a plurality of bus interface units (BIUs), each connected to a transmission bus having a straight-line topology at respective spaced locations along said bus, each respective BIU including: (A) transmission means for transmitting information packets on said bus, said transmission means being operable in: (1) a contention mode wherein said transmission means completes the transmission of an information packet only after that respective BIU senses said bus and determines that no additional information packets are also being simultaneously transmitted on said bus; and (2) a token passing mode wherein said transmission means transmits and information packet only after the expiration of a time interval unique to that respective BIU and determined by the relative location of that respective BIU and the last BIU to transmit one of an information and a start-up packet on said bus; and (b) control means for causing said transmission means to switch between said contention and token passing modes of operation as a function of the transmission activity on said bus.