| 摘要 |
PURPOSE:To take a proper measure against a fault, by judging that a fault occurs in an opposite information transmitting and receiving device when continuous ''1'' signals are detected in the receiving signal of an information transmitting and receiving device and by judging that a fault occurs in an information transmission line when the receiving signal is a ''0'' signal. CONSTITUTION:An information transmitting and receiving device 1' consists of an information transmitting and receiving part 11 and a signal discriminating part 12, and a modulating and demodulating device 3' consists of a modulating and demodulating part 31 and a signal converting part 32. The device 3' transfers the ''1'' signal from a signal transmitting circuit 33 to the modulating and demodulating part 31 continuously and transmits a carrier wave to an information transmission line 5. When a prescribed or more number of continuous ''1'' signals are detected from the receiving signal by the signal discriminating part 12 of the device 1', these signals are sent to the transmitting part 11 to judge that a fault occurs in an opposite transmitting and receiving device. Meanwhile, when the coming carrier wave is broken in the device 3', the modulating and demodulating part 31 sends the ''0'' signal to the signal discriminating part 12 of the device 1', and the ''1'' signal is supplied to the transmitting and receiving part 11 to judge that a fault occurs in the transmission line 5. |
