| 摘要 |
PURPOSE:To realize the profitability and simplification of a monitoring circuit by monitoring separately a lower order group input interface part, a multiplexing part, a higher order group output interface part, a higher order group input interface part, a demultiplexing part, and a lower order group output interface part, respectively. CONSTITUTION:An existing system multiplexer 17 and a stand-by multiplexer 18 are switched by changeover switches 19, 20, and these switches 19, 20 are operated by switching control signals 22, 23 outputted from a switching control part 21. In the switching control part 21, results of monitoring (signals 24-33) of the multiplexer 17 and 18 are inputted, and by these information, the existing system is switched to the stand-by system. That is, a detection of a fault of the multiplexer 17 of the existing system is executed, and when it is decided to be a fault, the system is switched. When a lower order group output signal disconnection or a higher order group output signal disconnection is detected, it is decided that the lower order group output interface concerned or the higher order group output interface has caused a fault.
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