| 摘要 |
PURPOSE:To detect a state variation of a supervisory item by a slave station, and thereafter, to make a delay time required until it is transmitted to a master station constant value which does not depend on the number of slave stations, by supervising a state of the supervisory item of the own station, stopping the transmission of a signal consistng of single frequency when a variation is recognized in the stage of the supervisory item, and operating a polling signal transmitting circuit of the master station. CONSTITUTION:A circuit 17 of a master station 1 always receives single frequencies 19, 19', 19''... from slave stations 2, 2', 2''..., but when the single frequency 19 cannot be received, it is stopped to send out a specified control signal 18, instead of which a polling signal transmitting circuit 5 is operated, and a polling signal 3 is sent out to the slave station 2. The slave station 2 receives the polling signal 3, and transmits to the master station 1 a response signal 4 containing a signal for transferring a state of a supervisory item of the own station. During this time, the slave stations 2', 2''... stop temporarily sending out 19', 19''.... When said polling response signal 4 is received, a polling response receiving circuit 11 of the master station 1 sends out the specified control signal 18 again, and each slave station makes preparations to send out 19, 19', 19''.... |
