| 摘要 |
PURPOSE:To make a device compact and low in cost by providing a state change signal generator and a transmitting signal generator on each slave station, and also providing an MODEM having a common modulating part, on both the generators, in a pair of N information transmitting systems of a pollying system. CONSTITUTION:When a state change is generated in a slave station A which is not in the course of selecting a station, an output of a state change signal generator 8 of its slave station A becomes '1', an input of a modulating part 5b of an MODEM5 becomes '1', and output signal of the MODEM5 becomes '1'. In case of executing polling for detecting a state change of the remaining slave station A, when the master station detects a signal of '1' from this slave station A, the master station sends a signal of a selection end to the slave station A which is transmitting data at present, and connects a switch 3 to the station A which has informed a state change, when the data transmission has been ended. Subsequently, when a selecting signal of a station is sent out to the slave station a which has informed the state change, from the master station, its slave station a transmits data to the master station, and transmits a signal of a selection end to the slave station a from the master station, when the transmission has been ended in a general way.
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