| 摘要 |
PURPOSE:To improve the expandability of a transmission system, by responding to the kind of affirmative response transmitted by a designated terminal responding to a command in which the terminal is designated transmitted by a main station, and switching transmission speed in data communication performed hereafter between said terminal and the main station. CONSTITUTION:The main station 1 performs the data communication with the terminal 2 while designating the terminal 2 in order via a data transmission line L1. The affirmative responses ACK1-ACK3 are the affirmative responses issued at the same reference transmission speed corresponding to the command of the reference transmission speed from each of the terminals 21-2n, and based on the kind of the affirmative response ACK1-ACK3, the transmission speed of the data communication to be performed hereafter between the terminal 2 and the main station 1 is designated. In such a way, communication with the terminal for which no increase of the transmission speed is required is performed at on-going transmission speed, and the communication with the terminal between which a large amount of communication data are transferred and for which the increase of the transmission speed is required to manage a response time within a prescribed time is performed at high transmission speed. In such a way, it is possible to enhance the expandability of the system without changing the whole of the system even when the amount of the communication data of the system is increased.
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