| 摘要 |
PURPOSE:To attain normal communication at the generation of a failure by providing an auxiliary transmission line possible for two-way transfer between a loop control station and a node station to change a part of the transmission line to the auxiliary transfer line by means of modification command. CONSTITUTION:A loop control station 1 and a suitable station 23 in node stations 21-25 are connected directly by the auxiliary transmission line 4 possible for two-way transmission. If two failues occur in a transmission line 3 and the stations 21-25 of the station 1, a means generating a loopback command is provided to the node station near failed positions. A part of the transmission line 3 is changed to the auxiliary transmission line 4 to form other transmission to the station 23 connected to the auxiliary transmission line 4 by this loopback command. Further, if the transmission line 3 is opened at a point C, a command is given from the station 1 to the stations 22, 23, and a main transmission line 3a, the transmission line 3 and a spare transmission line 3b are used to transmit data normally. |
