| 摘要 |
PURPOSE:To detect accurately the break of an light input due to a fault of an opposite station, by transmitting and receiving data with codes which are inverted in code logic of transmission code and receiving code with each other. CONSTITUTION:In case of CMI codes, (a) is a transmit signal waveform and (b) is a receive signal waveform; and those transmit and receive signals are inverted in polarity. If a fault occurs to the electrooptic conversion part 5 of the opposite station 2 and the transmission of a transmit signal C from the opposite station 2 is interrupted, a transmit signal B of this receiving station 1 leaks to an optoelectric conversion part 7. The CMI code showing the information 0 of the transmit signal B, however, is 01 and an error detecting circuit 8 sends out a warning signal when detecting the CMI code 01. Therefore, the break of the light input signal is detected immediately. In case excepting the CMI codes, codes inverted in the polarity of the codes of the transmission signal transmitted from the own station and an opposite station are usable. |
