| 摘要 |
PURPOSE:To prevent each local station from being completely isolated from a transmission line by providing each station with a means for returning the controlling information including a returning command to the transmission line and other information independently by a command from a monitoring station. CONSTITUTION:When a signal including a returning command CMDf is transmitted from a monitoring station (not shown) to a communication station STn through a signal line 0, said signal is outputted from the receiving terminal OR of a transmission unit T/R0 to a transmitting terminal OS and, simultaneously, inputted to a microprocessor MPU through a bus BUS. The MPU decodes the inputted signal and drives a relay winding RL1 in terms of time division through a relay driving circuit REG, so that a contact rl1 is switched under control like a dot line in the drawing so as to be folded only in the data area in a frame. Since the relay winding RL1 is not driven in the control signal area in the frame, said returning command signal is transmitted to a succeeding communication station through a contact rl0. |
