| 摘要 |
PURPOSE:To detect exactly a serious fault of a slave station side, and to decrease the number of lines between the slave station and a master station being a maintenance toll center, by providing an incoming terminal corresponding to the slave station, and a timer for bringing an incoming to a time limit monitor, on the master station side, executing a transmission within a prescribed time to be incoming terminal from the slave station, and resetting the time limit monitor timer. CONSTITUTION:In a master station side, timers TIMERa-TIMERn for monitoring time limit are provided in accordance with incoming terminals (a)-(n) corresponding to a slave station. A reset terminal of a monitor timer for monitoring time limit is connected to each corresponding incoming terminal (a)-(n), and for instance, in case of incoming to the terminal (a), timer 12 for monitoring time limit is reset to '0'. When the slave station becomes an operating state, it executes a transmission by using an optional line to the incoming terminal corresponding to the slave station, within a prescribed time which has been set to a timer for monitoring time limit of the master station. When a serious fault such as a system-down, etc. has been generated in the slave station, the transmitting operation becomes impossible, therefore, the timer for monitoring time limit of the master station overflows, and the fault of the slave station can be detected.
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