| 摘要 |
PURPOSE:To eliminate the changes of hardware and software on a terminal side by transmitting data between terminals connected to a master station and selected secondary station by means of the same transmission line and again transmitting control data between the master station and secondary station when the input of receiving data is interrupted between the master station and secondary station. CONSTITUTION:When an input interruption detecting circuit 3 detects the input interruption in the receiving data (k) of a transmission line and a signal (d) is outputted, a control circuit 4 actuates a timer 1 by outputting a signal (f) and, at the same time, connects control data (g) with transmission line transmitting data (c) by outputting a signal (i). A master station controls the signal (g) of a control data transmitting/ receiving circuit 5 and transmits control data for selecting a secondary station to be connected. The secondary station receives the control data by means of the control data transmitting/receiving circuit 5 and inputs the control data to the control circuit 4 as a signal (h). When the timer 1 times out and a signal (e) is outputted, the signal (i) is inputted to the master station and the switching circuits 2 and 6 of the selected secondary station and transmitting/receiving data (b) and (a) to and from a terminal are respectively connected with transmission line transmission/receiving data (c) and (k).
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