| 摘要 |
PURPOSE:To continue the signal transmission even when a trouble happened to the line connection a primary station and plural number of a secondary station in loop, by changing the primary station to loop back mode and turning back the signal from the adjacent station to the trouble. CONSTITUTION:Plural number of secondary stations 2-5 are connected in loop to a primary station 1 by two-core transmission cable 6. The primary station 1 outputs poling signal, start signal and data signal from its output terminal 1-0. The secondary station takes in the poling signal and when own station is specified, receives the data by the start signal from the higher rank station and sends out data of own station to lower station. When own station is not specified, it delivers the data to the lower station. When no start signal nor data signal is received at input terminal 1-i, the primary station 1 is changed to loop back mode, and sends out signals from both input and output terminals, and receives by both terminals the signal returned back from the adjacent station to the trouble. In this way, the multiples transmission can be continued even when there occurs a trouble.
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