| 摘要 |
PURPOSE:To transmit data without lowering processing capacity of a terminal other than terminals to which data are transmitted to the extent of capacity more than necessary by making each terminal receive the address of a telegram when it is detected that respective signal level is kept at a level different from a level when data are not transmitted for a specified time. CONSTITUTION:A transmission line 6 is a serial transmission line that transmits data sent from a sending circuit 1 one bit by one bit, and normally kept at a high level ''H'' when data are not transmitted. A receiving circuit 2 receives succeeding data block only when the telegram sent from the sending circuit 1 is addressed to own station, and takes out the data. A transmission line monitoring circuit 7 monitors the condition of the transmission line 6 and detects whether a telegram is transmitted to the transmission line 6 or not. That is, the transmission line monitoring circuit 7 starts clocking when the transmission line 6 changes from high level ''H'' to low level ''L'' at time t0, and reports to an interruption circuit 8 the fact that the telegram is transmitted in the transmission line 6 at a time t1 elapsed t' seconds after starting clocking.
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