| 摘要 |
PURPOSE:To simplfy a system arrangement without impressing a direct current and to reduce the number of parts by including a transmitted signal with frame synchronizing information, taking out said information at the reception side and applying a synchronous protection to the information so as to make it into an activating signal. CONSTITUTION:Exclusively used electric power sources are installed on the terminal equipment 1 and terminal controller 2 of a system respectively, and electric power is supplied always to the interface circuits 4 and 11 of the equipment 1 and controller 2 and synchronous protection circuits 25 and 26 from the exclusively used electric power sources. When the equipment 1 transmits a signal, the circuit 4 transmits the signal to a line T through a transformer 7 with the activating signal 17, and the frame synchronous information included in said signal is transmitted. The signal is received by the circuit 11 through a transformer 14, and the synchronous information is taken out. Then the circuit 26 applies the protection during a certain period to turn on an output 21. An incoming signal to the equipment 1 from the controller 2 is transmitted in the same manner, and the number of parts in the system is reduced without impressing a direct current and its constitution is simplified.
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