| 摘要 |
PURPOSE:To miniaturize a storage battery used during power failure by minimizing a circuit operating during the power failure by adding a function of transmitting information on the power failure to the transmission part of a modulator-demodulator and by informing a master station of the power failure. CONSTITUTION:The equipment which performs data transmission by using a frequency shift modulation system is provided with transmission part 1, reception part 2 and DC power source circuit 5; an AC voltage from power-source input terminal 21 is converted by circuit 5 into a DC voltage, which is applied to transmission part 1 and reception part 2. To this circuit 5, power-failure information detection and power source switching relay part 3 connected to storage battery 4 is connected. Further, transmission part 1 is provided with transmission input terminal 17, transmission output terminal 19 and circuit block 6 which operates during a power failure, and reception part 2 with reception data output terminal 18 and reception input terminal 20. On a power failure, contacts a1 and a2 of relay part 3 are changed over to contact b1 and b2 to transfer the power failure information to the master station while minimizing the operating circuit of transmission part 1, so that storage battery 4 used during the power failure is minimized. |
