| 摘要 |
PURPOSE:To improve remarkably the reliability of the entire system by providing the 2nd transmission line transmitting a data in opposite direction in addition to the 1st transmission line transmitting data normally and forming a new loop with the 1st and 2nd transmission lines when a station existing just at the downstream position of an open line fault detects the open line fault so as to continue communication. CONSTITUTION:A CPU 4 controls a transmission/reception switch circuit 2 and an error signal generating circuit 13, an error signal is being outputted during the open line fault from the error signal generating circuit 13 and the signal is transmitted to an upperstream station Ti-1 through a transmission circuit 8 and a transmission line Li-1. Through the constitution above, if an open line fault takes place between stations ST 2 and ST 3, a signal from a transmission line R1 is reflected on the station ST 2 and transmitted in the part of ST2 L1 ST1 Ln - L3 ST3, while the data signal from a transmission line L3 is reflected on the station ST 3 and transmitted in the path of ST3 R3 ST4 - R1 ST2, finally a new loop subject to loopback by the stations STs 2, 3 is constituted to continue the communication.
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