| 摘要 |
PROBLEM TO BE SOLVED: To provide a communication system, where a master station can always control/manage its slave stations with no interruption of the system operation, even when the faults occur or the slave stations are added. SOLUTION: A master station 11 is connected to its slave stations 12 or the stations 12 are connected to each other, via channels 14 set opposite to each other. Thus, a double-loop, structure is obtained. In a normal state, a control/management communication virtual path of a working system is set at only the single side of a loop between the stations 11 and 12 by means of the channels 14 of the double-loop structure. On the other hand, a control/ management communication virtual path of a standby system is set at the other side of the loop in a state, where the virtual path is cut at its middle part. If a fault occurs and the virtual path of the working system is cut, the station 11 or 12 sets the cut part of the path of the working system to complete a virtual path of the standby system. Thus, the control/management communication is restored between the stations 11 and 12.
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