A distributed control system for controlling a plurality of controlled objects, comprising:
- at least one transmission path divided into a plurality of sections to which said plurality of controlled objects are respectively connected;
- a plurality of controllers connected in cascade by the sections of said transmission path so that each controller is allocated to normally control an associated one of said controlled objects and to monitor the status of at least one of the other controllers normally connected thereto by one of said transmission path sections, each controller comprising:
- (a) first and second transmitter/receivers;
- (b) memory means having a capacity for storing data used for controlling at least two of said controlled objects;
- (c) switching means selectively operable in a first mode for connecting said first transmitter/receiver to one section of said transmission path to which the associated controlled object is connected and for connecting said second transmitter/receiver to a preceding section of said transmission path to which a preceding one of said controllers allocated to monitor the controller is connected or in a second mode for disconnecting said first and second transmitter/receivers from said one and preceding sections of said transmission path and for connecting said one and preceding sections to each other to bypass the controller on said transmission path;
- (d) switch control means for controlling said switching means to operate in said first mode when the controller is in a normal condition and in said second mode when the controller is in an abnormal condition;
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- (e) control means operating when said switching means operates in said first mode to transmit first data stored in said memory means through said first transmitter/receiver to the associated controlled object for controlling the same, to receive through said first transmitter/receiver second data to be stored in said memory means of a succeeding one of the controllers on said transmission path whose status is monitored by the controller, said second data including data which is used by said succeeding controller for controlling its associated controlled object and which is stored in the memory means of the controller for the purpose of controlling the succeeding controller's associated controlled object when said succeeding controller is judged to be abnormal, and to transmit said first data through said second transmitter/receiver to the first transmitter/receiver of the preceding controller.