| 摘要 |
PURPOSE:To easily enhance the reliability of a communication system by adding a transmission sequence control number to every transmission data and transmitting the data. CONSTITUTION:When a transmission side communication equipment 1 transmits the data, a reception side communication equipment 4 receives the data through a line terminal equipment 2, a communication line 5 and a line terminal equipment 3. According to the transmission sequence control number added to the reception data, the communication equipment 4 judges whether the reception data is valid or invalid. If the data is invalid, it is abandoned. When the data is valid, it is stored. Moreover, the communication equipment 4 checks the transmission error of the data, and if there is an error, it transmits a transmission error abnormal response signal to the communication equipment 1. When the equipment 1 receives the transmission error abnormal response signal, it agains transmits the data added with the same transmission sequence control number as that of the data that has been transmitted.
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