| 摘要 |
PURPOSE:To discriminate abnormality without complicating an equipment, and also, without being influenced by the fluctuation of a transmission speed, by detecting the abnormality as a specific pattern, converting it to a voltage by a voltage converting means provided on a receiving means, and discriminating the abnormality, based on the level of this converted voltage, and a fact that said level has lapsed a prescribed time. CONSTITUTION:A service interruption detecting circuit 13 detects a service interruption and switches a power supply to a backup power source 11 from a supply power source 43, thereafter, outputs a detecting signal to a current ON/OFF control circuit 15a. Due to the time of service interruption, a current ON/OFF circuit 17 switches an input control from a data transmitter 1 to the current ON/OFF control circuit 15a and transmits the current to a current ON/OFF detecting circuit 19, while bringing it to an ON-OFF control, through a code item line 5. When the current is transmitted, the current ON/OFF detecting circuit 19 detects the current and outputs it to a voltage converting circuit 21. The voltage converting circuit 21 converts the inputted current to a voltage, and a voltage deciding circuit 23a decides an allowable range from the level of the voltage and the continuation of a prescribed time, and outputs a deciding signal to a service interruption detecting and outputting circuit 25.
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