| 摘要 |
PURPOSE:To secure high reliability, while decreasing the number of additional line to the utmost by transmitting a data signal by superposing it on a DC voltage signal, and setting it as a command signal of a safety side by disconnecting a DC component. CONSTITUTION:Transmission and reception of data between plural transmission terminals 1, 2 and 3 are executed by a high frequency pulse superposed onto a DC voltage V1 by transmission lines 4, 5. Accordingly, even if the DC applied voltage V1 of the transmission lines 4, 5 is disconnected, unless the transmission lines 4, 5 are disconnected, an AC waveform is transmitted, and a data transmission can be executed. Accordingly, by turning on and off an output voltage of a power source 6, turn-on/turn-off signals can be transferred separately from the above data by using the same transmission lines 4, 5. Relays provided in the terminals 1, 2 and 3 are controlled by whether this DC voltage V1 exists or not. In such a way, other signal than the data transmission can be sent without increasing the number of electric wires. |
