| 摘要 |
PROBLEM TO BE SOLVED: To arbitrate a data bus by using a diagnostic bus. SOLUTION: A diagnostic processor 90 issues a command for permitting a data controller 10a to use the data bus 100 through the diagnostic bus 110. A diagnostic control part 30a of the data controller 10a having received this command informs a processor 20a that its data controller 10a is selected and the right to use the data bus 100 is given. When there is a data transfer request, the processor 20a sets an answer code indicating that the bus is in use in the diagnostic control part 30a, and then transfers data through the data bus 100 and sets an answer code indicating that the bus is not used after the transfer. The diagnostic processor 90 gives respective data controllers 10 the right to use the data bus 100 in order according to the answer code.
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