Communication control method and system

The invention discloses a communication control method and system, and the method comprises the steps: carrying out the configuration of a communication control word and a state word between an automation device and a transmission device, and building a communication network; presetting any bit in any control word in the transmission device as a heartbeat signal bit, and setting any external faultbit as an active judgment fault response mode; activating a user-defined functional block in the transmission device, and configuring two time relay functional blocks; generating a heartbeat signal according to the time relay function block; connecting the heartbeat signal to a heartbeat signal bit, and transmitting the heartbeat signal to an automation device through a communication network; enabling the automatic device to feed back the heartbeat signal to a corresponding control word in the transmission device; enabling the transmission device to judge whether the heartbeat signal is abnormal; and if yes, actively