| 摘要 |
PROBLEM TO BE SOLVED: To reduce power consumption by turning off a 1st switch so as to stop power supply when a power interruption confirmation information reception means receives power interruption confirmation information. SOLUTION: When an interface 8#i is not in use, a maintenance personnel or the like uses a power interruption instruction means 10#i to instruct a power interruption notice information insertion means 12#i to interrupt the power of the interface 8#i. The power interruption notice information insertion means 12#i receiving the instruction of power interruption inserts power interruption notice information to a 1st prescribed bit of a 1st frame transmitted to a host device 4. The 1st frame is sent to the host device 4. Upon the receipt of the power interruption notice information, the host device 4 inserts power interruption confirmation information to a 2nd prescribed bit of a 2nd frame and transmits the resulting frame to the interface 8#i. Upon receiving power interruption confirmation information of the 2nd frame, a power interruption confirmation information reception means 13#i turns off a 1st switch 11#i. In the case the power interruption confirmation information cannot be received within a prescribed time after the transmission of the power interruption notice information, the means 13#i warns an alarm means 14#i about it.
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