| 摘要 |
PURPOSE:To avoid collision of plural data sent to a transmission line at the same time by setting an intrinsic waiting time different from each terminal device and changing the timing of data transmission depending on the waiting time when the transmission request of the intrinsic data is caused. CONSTITUTION:Wait times W1-Wn (W1<W2-Wn) specific to a terminal device are assigned respectively to terminal devices 5a-5n. When a transmission request of intrinsic data is caused in the terminal device 5, the intrinsic data is sent at the elapse of the intrinsic waiting time Wa after the carrier of the call signal is lost. As rep data to the call from a center unit 1, a data such as metering data of water supply or gas supply with a low emergency or line fault sensing data is assigned. On the other hand, as a intrinsic data sent depending on the discrimination by the terminal unit itself by the carrier sense multiple access CSMA system with high emergency, a fault detection data such as fire, leakage of gas or burglar is assigned.
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