| 摘要 |
<p>PURPOSE:To select a data terminal equipment not by manual operation by providing a suppression control means suppressing the communication between the terminal equipment and a line after a communication request comes from one terminal equipment. CONSTITUTION:A selection circuit 11 consists of reception circuits 101, 103, transmission circuits 102, 104, a NOT circuit 105, an AND circuit 106 and an RE flip-flop 107. For example, an output of a reception circuit 101 and a transmission circuit 102 for a DTE(data terminal equipment) interface 1 is valid only when an output signal SEL 1 of the flip-flop circuit 107 is set. Then the signals SEL 1, 2 are so formed that the one is set while the other is reset without fail, and a data terminal equipment of the interface 1 or 2 where a signal ER1 or ER2 relating to the line connection state is set earlier is enabled. Thus, the communication enable data terminal equipment is switched automatically by a line connection signal outputted from each data terminal equipment.</p> |
