| 摘要 |
<p>PURPOSE:To securely prevent the confusion of a master device in case of a fault of the power source on a slave device side, by sending an information reception stop signal out of a monitoring circuit of slave-device-side power source, which operates by the master-device-side power source, to the master-device-side interface part all the time. CONSTITUTION:A power source monitoring circuit 25 provided to an input and output device 2 which transmits and receives information to and from a master device 1 operates by receiving electric power 12 from the power source device 11 of a central controller 1 to monitor electric power 22 supplied from the power source device 21 of the input and output device 2. In the monitoring circuit 25, a comparator 26 compares the minimum permissible voltage of the device 2, generated from the electric power 12 through a constant voltage diode 27, with the electric power 22 of the input and output device 2 invariably; the circuit 25, once detecting the electric power 22 dopping below the minimum permissible voltage, sends a fault signal 5 to the central controller immediately to stop the reception of information 4 by the receiving circuit 14 of an interface part 13.</p> |
