Abstract: A signal transmission/monitoring method for a system including a master station and a plurality of slave stations installed on and along a signal transmission line so as to be capable of mutually performing information transmission and reception in such a manner that the master station calls the slave stations through sequential polling with the called slave station sending reply information to the master station. An interrupt enable time zone is provided between a time point at which the call signal transmission from the master station is completed and a time point at which the reply signal transmission from the slave station is started. When other slave station issues an interrupt request within the interrupt enable time zone, signal transmission to the master station from that other slave station is carried out with priority.

Abstract: A remote monitor control system comprises a single master station having the function of communication in synchronism with communication clocks for generating various commands required for monitor and control, and a plurality of terminal stations having the function of communication in synchronism with the communication clocks for receiving data related to objects of monitor and controlling objects of control. The terminal stations are caused to respond at different time points sequentially predetermined different times after transmission from the master station. When a sync signal fails to be received for a predetermined length of time, the predetermined time set for a particular station is shortened.