| 摘要 |
PURPOSE:To efficiency improve data collection by branch transmitting a received data signal from a slave station to a prescribed slave station in a master station, detecting the disconnection of the carrier of the transmission signal of the master station in the slave station and controlling the timing of a data transmission to the master station, in a 1 to N polling system. CONSTITUTION:A carrier signal is transmitted from a carrier transmission part 101 to a first data collection slave station 110 by the connecting means 105 of the master station 11, the received slave station 110 detects the disconnection of the carrier signal by a data transmission control means 113 and transmits the data to the master station 100. In the master station 100, this data signal is fetched to a data receiving part 103 and transmitted directly to the next data collection slave station 120, and then the received slave station 120 detects the disconnection of the carrier signal with the completion of the data transmission of the slave station 110 and transmits the data to the master station 100. In such a way, the master station freely sets the slave stations 110-140, the master station monitors the data signal of the previously data collecting slave station and transmits the data in time division to the master station 100, so that the data collection efficiency can be improved.
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