| 摘要 |
PURPOSE:To securely detect the reception of overwrapped transfer data by adding serial numbers to transmission data and transmitting them. CONSTITUTION:A CPU5 in a node 2 transmits transmission data on a network transmission path 1 through a transmission/reception circuit 4. The transmission data store the content of the transmission data serial numbers (SEQ) in a RAM7 in the SEQ47 of a data frame. If an error occurs in an answer frame which has been transmitted from a node on a reception side and a data transmission source node could not detect an answer, a re-transmission processing is executed in the transmission side node. Since the serial numbers are not updated in such a case, the SEQ47 of the data frame to be transmitted shows the same value as the last time. Thus, it is eliminated that overwrapped data are errorneously received.
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