| 摘要 |
PURPOSE:To allow a master station side to discriminate whether a fault exists in a transmission line or in a slave station main body by transmitting an intermission signal to each slave station from the master station when the fault is detected so as to supervise a response signal transmitted in time series from each slave station. CONSTITUTION:When the master station detects the fault of the slave station side, an intermission generator 15 is activated so as to output an intermission signal to an outgoing transmission line 31. Each slave station receiving said intermission signal activates a line connection drive circuit 44 via a one-shot multivibrator circuit 43 with on-delay and outputs a signal of a modulator 46 to an incoming transmission line 32. In this case, since the on-delay timer value is different from each slave station in the one-shot multivibrator circuit 43, a signal from each slave station appears in time series to the incoming transmission line 32. Thus, the master station 1 discriminates the fault of transmission line by supervising the missing of the signal from each slave station. |
