| 摘要 |
PROBLEM TO BE SOLVED: To prevent risk of dividing a network loop in a state where a loop- back is generated by transmitting a previous stop notice to another station in the case of the stop for maintenance and confirming that the loop-back is not generated. SOLUTION: When the desired station 3-1 is stopped for maintenance, a maintenance worker indicates the transmission of stop schedule information to the station 3-1 to a network monitoring device 50. Stop schedule information periodically transmitted from the network monitoring device 50 is stored in a table in a self station stop judging part 6 by way of the transmission/reception control part 19 and the self station stop schedule information receiving part 9 of the station 3-1. In this case, when the loop-back occurs in the station 3-1, it is announced to the other stations 3-1 to 3-5 by the route of a self station loop-back detecting part 16, a self station loop-back information transmitting part 17, the transmission/reception control part 19 and a transmission line 2. Besides, an alarm display part 8 displays that the stop of the station is not allowed during the occurrence of the loop-back with an alarm output part 7.
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