| 摘要 |
PURPOSE:To enable a data transmitting station to recognize the number of data receiving stations and receiving state in each receiving station by forming an area capable of reflecting the receiving state of each receiving station in the data. CONSTITUTION:Plural data terminal units (DTU) 15 are connected to loop transmission lines 13, 14. When the DTU 15 is a transmitting station, data in a data processing part 23 are set up 21 to a prescribed format, a destination station address is set up 21 and receiving state is added to a status control part 20 and sent from a transmission part 19 to the transmission line 14. When the DTU 15 is a receiving station, the receiving status is detected 17 by discriminating transmission to the self-station in a reception control part 16 and informed to a receiving status setting part 20, the receiving state of the self- station is added to the receiving state and the added receiving status is transmitted 19. If the receiving state is not transmitted to the self-station, it is by-passed 18. Consequently, the transmitting DTU 15 can recognize the receiving state of other DTUs together with the number of stations.
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