초록 ▼

A distributed, electronic process control system is disclosed having a plurality of remotely located stations interacting to control a complex industrial process. The stations communicate via a process communication link which supports secure, multi-master communication. The link provides a transpar

A distributed, electronic process control system is disclosed having a plurality of remotely located stations interacting to control a complex industrial process. The stations communicate via a process communication link which supports secure, multi-master communication. The link provides a transparent medium of exchange for the secure transfer of process status and control information among the stations, such that each station may initiate and control system communication for a predetermined time period.

대표청구항 ▼

In a system for controlling a complex industrial process of the type having a large number of process conditions, such as temperature, fluid flow rate, and so forth, which conditions are to be maintained at respective set point magnitudes alterable in accordance with certain changeable process requi

In a system for controlling a complex industrial process of the type having a large number of process conditions, such as temperature, fluid flow rate, and so forth, which conditions are to be maintained at respective set point magnitudes alterable in accordance with certain changeable process requirements, said control system comprising a plurality of separate but interactive stations organized in a number of preselected groups, each of said stations developing station request flag signals when communication is required by any of said stations with another of said stations; at least some of said stations being arranged to be coupled to corresponding process control unit means including control units of the type which are responsive to condition measurement signals and are operable to produce control signals for respective process devices such as flow control valves functioning to adjust process variables to maintain corresponding process conditions at selected set-point values; said process control system further including a process communication link providing communication between any one of said stations developing a request flag signal and a second station to which a message is to be directed by said requesting station; said process communication link comprising: (a) a plurality of link ports each assigned to a corresponding one of said preselected groups of stations; (b) transmission means interconnecting all of said link ports and including means to provide bi-directional communication therebetween; (c) each of said link ports including: (1) means to receive said station request flag signals from all stations of the group assigned to the link port; (2) scanning means coupled to said receiving means and operable to detect a station request flag signal received from any of said assigned group of stations; (3) means to deactivate the further functioning of said scanning means upon detection of a station request flag signal; (4) means responsive to the detection of a station request flag signal by said scanning means for developing and coupling to said transmission means a group request flag signal including an identification of the link port originating the group request flag signal; (d) a link control coupled to said transmission means and including: (5) means to receive all of the group request flag signals from said link ports; (6) scanning means coupled to said receiving means (5) and operable to detect a group request flag signal received from any of said link ports; (7) means responsive to the detection of a group request flag signal for developing and coupling to said transmission means a group grant signal including an identification of the link port for the station to be granted communication access to said transmission means; (e) all of said link ports further including: (8) means coupled to said transmission means to receive all of the group grant signals produced by said link control station and to recognize the signals identifying the associated link port; (9) means responsive to said receiving a recognition means for developing a station grant signal upon recognition of a group grant signal identifying the associated link port; (10) means jointly operable with said responsive means (9) for directing said station grant signal to the station which originated the original station request flag signal; and (11) means coupling any of the assigned stations to said transmission means whereby a station upon receipt of a station grant signal can commence transmitting a message to any other of said stations.