| 摘要 |
PURPOSE:To attain the collection of state data grasped by each slave station remotely and inexpensively by allowing the transmission side to convert a data signal into a tone signal utilizing a DTMF signal (Dual Tone Multi Fre quency), placing the signal on a public telephone line and allowing the reception side to convert this signal into a BCD signal. CONSTITUTION:A line connection detecting switch 1 is connected manually to the position 1b to call a slave station A from a master station B and a one-touch dial key 3 is depressed, the tone signal of the telephone number of the slave station is outputted to a public telephone line 6a by automatic dial functions 4. When the slave station A is connected to a line, the power supply from the telephone station 6 is supplied to the exchange power conversion circuit 12 and the data inputted by a ten-key 13 is converted into tone signal utilizing a DTMF signal by a tone signal generation circuit 14 and transmitted to a public telephone line 6b by a tone signal output circuit 15, the tone signal is converted into a BCD signal by a tone/BCD converter 17 of the master station B via a telephone station exchange 6 and data is displayed on a data display device 18.
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