| 摘要 |
A multiplex transmission apparatus in accordance with the present invention is interconnected with other multiplex transmission apparatuses via common transmission lines, and it is used for a multiplex transmission system which performs data transmission. The multiplex transmission apparatus comprises voltage converting circuits which detect voltages of the transmission lines, the first comparator which compares the detected voltages, the second comparator which compares one voltage of the detected voltages with a reference voltage, and the third comparator which compares the other detected voltage with a reference voltage. The comparators supply the comparison results to differential circuits, respectively, set the output of the differential circuit linked to a comparator, which is connected to a faulty line, for "L", and determine the logical sum of the outputs of the differential circuits by a logical synthesizing circuit. By applying the determined logical sum to a multiplex transmission control circuit, the apparatus makes it possible to reduce wasteful message transmission and successfully cope with faults in the transmission lines without causing delay in transmission of messages which require quick responses and without increasing the traffic volume of the transmission lines. The multiplex transmission control circuit detects signals on the transmission lines according to the comparison results of the comparators.
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