Abstract: In a distributed computer control system in which remote stations are interconnected by a communications link, the remote stations take turns having supervisory control over the communications link. Each remote is numbered in sequence in a predetermined succession order and takes its turn having control of the communications link in accordance with this succession order. When a remote station has completed its turn of having supervisory control, it transmits a first control message over the communications link. The next remote station in the succession order then takes control over the communications link by transmitting a second control message over the communications link. Each remote station has two variable timers which are set in response to the first control message and the second control message, respectively, and have time out intervals depending upon the offset of the receiving remote station from the remote station which transmitted the control message.

Abstract: A control system for controlling an industrial process includes a plurality of remotely located process control units (remotes) each coupled to an associated input/output device(s) and adapted to communicate with one another through a dual channel communications link. Each remote has a unique succession number within a predetermined succession order with supervisory communication-control of the communication link sequentially transferred to each remote according to its succession number to provide a revolving or master for the moment control of the system. Each remote after completing its turn as master transmits a control block to the next remote in the sequence. Each remote, when exercising supervisory communication control of the communication link, may transmit data in block form to other remotes and request and receive data back from other remotes.

Abstract: A control system for controlling an industrial process includes a plurality of remotely located process control units (remotes) each coupled to an associated input/output device(s) and adapted to communicate with one another through a dual channel communications link. Digital information in the form of data and control information blocks is transmitted between remotes with the blocks transmitted twice on each channel of the dual channel communications link. The destination remote checks the block validity on one of the dual channels and, if valid, responds with an acknowledgement signal (ACK), and, if invalid, tests the blocks on the other, alternate channel and then responds with an acknowledgement or non-acknowledgement signal (NAK) depending on whether the data blocks tested on the alternate channel are found valid or invalid.

Abstract: A control system for controlling an industrial process includes a plurality of remotely located process control units (remotes) each coupled to an associated input/output device(s) and adapted to communicate with one another through a dual channel communications link. Each remote has a unique succession number within a predetermined succession order with supervisory communication-control of the communication link sequentially transferred to each remote according to its succession number to provide a revolving or master for the moment control of the system. Digital information in the form of data and control information blocks is transmitted between the remotes with the blocks transmitted twice on each channel of the communications link.