| 摘要 |
PURPOSE:To improve the reliability of a data communication system by changing a continuation time of a transmittable signal in accordance with a data transfer speed, informing the data transfer speed to the other party side, and making the transfer speed coincide exactly between devices for sending and receiving the information. CONSTITUTION:Before data transfer is executed, a transmission requesting signal is outputted through a transmission requesting signal line 101 to a data terminal equipment 2 from a communication control device 1. In the data terminal equipment 2, with respect to the transmission requesting signal, a continuation time of a transmittable signal is changed in accordance with a transfer speed of the own device, and this transmittable signal is sent out to the communication control device 1 through a transmittable signal line 102. In the communication control device 1, the continuation time of the transmittable signal is detected and the same speed as the transfer speed of the data terminal equipment is set to the own device, and the data transfer is executed at this transfer speed. In case of a short continuation time T1 of the transmittable signal, the data transfer speed becomes high, and in case of a long continuation time T2 of the transmittable signal, the data transfer speed becomes low.
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