| 摘要 |
PURPOSE:To easily detect a fault at the occurence of fault in its own station by comparing a received data with a transmission data processing and sending the reception data in its own station and detecting the fault through the result of comparison. CONSTITUTION:The reception signal from a loop transmission line is retarded from a delay circuit 5 so as to be matched in timing with the transmission signal outputted from a code conversion circuit 3 by a delay circuit 5 and the retarded reception signal and the transmission signal outputted from the code conversion circuit 3 are compared by a comparison circuit 7. The comparison in the comparison circuit 7 is attained in the timing when the data is received by a transmission/reception circuit 4. In the timing when the data is sent from the transmission/reception circuit 4, the comparator circuit 7 is controlled by a comparison control circuit 6 so as to avoid the comparison. The presence of a fault in its own station is detected from the result of comparison by the comparison circuit 7. That is, when the reception signal retarded by the delay circuit 5 and the transmission signal outputted from the code conversion circuit 3 are dissident, it is regarded that a fault takes place.
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