| 摘要 |
PURPOSE:To transmit sequential data to a central device from the line of one system, by the constitution that each terminal device can sequentially be called from a common callout signal transmitted from the central device. CONSTITUTION:A plurality of terminal devices 2(2Ar, 2Br,...) of the same constitution are connected in series via a switch circuit 4 in each device, and the 1st terminal device 2A is connected to the central device 1. The switch circuit 4 electrically cuts off a terminal device 2B connected to the next stage at the initial stage with the central device 1, and when a callout signal is transmitted to the terminal device of itself from the terminal device of the prestage (central device in case of the 1st stage of terminal device), data is transmitted to the central device 1 through the transmission path. Further, when the data transmission is finished, the switch 4 is changed over to connect the terminal device of the next stage and the central device electrically, allowing to transmit the data of each terminal device sequentially to the central device. |
