Stored data rewriting system for on-board control unit

摘要

A rewriting system in which a rewriting unit (2) transmits rewriting data for each predetermined data transfer unit as a data transfer command together with specified position data which represents a portion to be rewritten which corresponds to the rewriting data and prohibits the transmission of the data transfer command which contains the rewriting data when the whole of the rewriting data that is transmitted by the predetermined data transfer unit represents a predetermined value, and an on-board control unit (3) writes the rewriting data contained in the received data transfer command to the rewriting portion of the nonvolatile memory (10) represented by the specified position data in the received data transfer command and writes data representing the predetermined value in all portions of the nonvolatile memory (10) where the rewriting data cannot be obtained from the received data transfer command.