CONTROL SYSTEM AND TIME SYNCHRONIZATION METHOD

PROBLEM TO BE SOLVED: To provide a control system in which a plurality of arithmetic devices for controlling a plant facility and others are connected via transmission lines, capable of synchronizing system times among the respective arithmetic devices.SOLUTION: In a control system, among a plurality of arithmetic devices, one is designated as a time master, and the others are designated as time slaves. A processor of the arithmetic device as the time master acquires a time of a system timer at a predetermined cycle, stores the acquired time in a network timer to allow the network timer to continue time keeping. Frame generation means acquires time information of the network timer, generates a frame including the time information, and broadcasts the frame to the arithmetic devices as the time slaves at a predetermined cycle. Frame reception means of the arithmetic device as the time slave stores the time information included in the transmitted frame in the network timer of the arithmetic device to allow the network timer to continue time keeping.