Multi-station token pass communication system.

摘要

A data communication system utilizing a synchronized serial bus (20) for communication between multiple stations (22) connected to the bus. A token is employed such that when owned by a station it allows that station to transmit high-level messages over the bus and command other stations to transmit high-level messages to it if required by the token owner. Fundamental events called primitives are perceived by stations. Each station capable of token ownership embodies the same set of rules, the rules in turn defining the circumstances when perceived events cause a station to change from one state to another.

Fundamental sets of rules, or modules, are used in the communication system to achieve a system for the automatic generation of a token list of stations with periodic ownership of the token, as well as for exapansion or contraction of this token list. In addition, automatic change in the token pass handshake protocol is described.

The communication system allows bus interconnection to stations having no potential token acess, with communication control provided by master stations which have token ownership capability.