| 摘要 |
PROBLEM TO BE SOLVED: To instantaneously identify transmission faults and the fault of a device to be monitored. SOLUTION: This device to be monitored connected through a reception side transmission line 21, and a transmission side transmission line 20 to a monitoring device is provided with a communication controller 10, a monitoring circuit 11 for monitoring the fault of the device to be monitored and a loop-back switch 17. When the monitoring circuit 11 detects a fault state such as a function stoppage of the device to be monitored, the loop-back switch 17 is actuated, and the state confirmation signals from the monitoring device received by the reception side transmission line 21 are looped back to the transmission side transmission line 20. The monitoring device discriminates the presence or the absence of signals received from the transmission side transmission line 20 and whether or not they are the state confirmation signals after the transmission of the state confirmation signals to the device to be monitored, and judges a fault condition and a fault part. |
