Industrial control system
First Claim
1. A distributed process control system comprising a plurality of primary control units interconnected by a communications link, each of said primary control units having a central processing unit and a plurality of input/output devices connected thereto, said input/output devices sensing the condition of and controlling the operation of a process, the central processing unit of each of said primary control units containing a stored applications program which responds to the condition of input devices connected thereto and controlling the output devices connected thereto in accordance with said applications program, each of said primary control units being operable to receive data from and transmit data to each of the other primary control units over said communications link, at least one redundant control unit connected to said communications link and operable to receive data from and transmit data to each of said primary control units connected to said communications link, said redundant control unit comprising a central processing unit with a stored program and comprising means to monitor said primary control units and to respond to the central processing unit of one of said primary control units failing to carry out its stored applications program, to carry out such applications program in the central processing unit of the redundant control unit, said redundant control unit receiving data from said one of said primary control units representing the condition of the input and output devices of the primary control unit over said communications link and sending instructions to said one of said primary control units to direct changes in the output devices of the primary control unit in accordance with such applications program being carried out in said redundant control unit, each primary control unit including means to respond to instructions received from said redundant control unit over said communications link directing changes in the output devices of such primary control unit to effect corresponding changes in the output devices of such primary control unit.
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Accused Products
Abstract
In an industrial control system, a plurality of remote data processing units communicate with one another over a communications link. Some of the processing units called primary remotes have inputs and outputs and control a process operation in response to signals received on the inputs by signals transmitted over the outputs. One or more of the remote processing units, referred to as a redundant remote, monitors a plurality of the other primary remotes to determine whether any of the monitored primary remotes has failed. If any of the primary remotes fails, the redundant remote takes over operation of the process controlled by the failed primary remote by sending instructions and commands over the communications link interconnecting the primary and redundant remotes.
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Citations
7 Claims
- 1. A distributed process control system comprising a plurality of primary control units interconnected by a communications link, each of said primary control units having a central processing unit and a plurality of input/output devices connected thereto, said input/output devices sensing the condition of and controlling the operation of a process, the central processing unit of each of said primary control units containing a stored applications program which responds to the condition of input devices connected thereto and controlling the output devices connected thereto in accordance with said applications program, each of said primary control units being operable to receive data from and transmit data to each of the other primary control units over said communications link, at least one redundant control unit connected to said communications link and operable to receive data from and transmit data to each of said primary control units connected to said communications link, said redundant control unit comprising a central processing unit with a stored program and comprising means to monitor said primary control units and to respond to the central processing unit of one of said primary control units failing to carry out its stored applications program, to carry out such applications program in the central processing unit of the redundant control unit, said redundant control unit receiving data from said one of said primary control units representing the condition of the input and output devices of the primary control unit over said communications link and sending instructions to said one of said primary control units to direct changes in the output devices of the primary control unit in accordance with such applications program being carried out in said redundant control unit, each primary control unit including means to respond to instructions received from said redundant control unit over said communications link directing changes in the output devices of such primary control unit to effect corresponding changes in the output devices of such primary control unit.
Specification