| 摘要 |
PURPOSE:To detect an electric power source condition of the terminal, to judge whether the communication is possible or not and to remove an unnecessary communication by installing an inquiry means to execute the general calling for respective terminals to an electronic computer and a means to respond to the calling to respective terminals. CONSTITUTION:When an inquiry means 12a of a computer 12 executes the general calling 15 to terminals 13 and 14, by returning responses 16a and 16b by response means 13a and 14a in accordance with the set procedure from terminals 13 and 14, the electronic computer 12 detects that an electric power source of the terminals 13 and 14 is present. When a response 16a does not return from the terminal 13, the computer detects that the electric power source of the terminal 13 is absent, and thereafter, until the electric power source of the terminal 13 is reinputted, an uncommunicable condition is obtained for the terminal 13. After that, the electronic computer 12 communicates 17 for the terminal 14 only. Thus, for the terminal 13 where an electric power source turning-off condition is found beforehand, unnecessary communication is not necessary and a transmission line 11 is efficiently used.
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