| 摘要 |
<p>PROBLEM TO BE SOLVED: To perform data communication at an appropriate communication speed and to shorten the rewrite time of ROM data. SOLUTION: On-vehicle ECUs 10, 20, 30 and 40 are communicably connected to each other with a communication bus 50. For instance, an erasable and rewritable flash E<2> PROM 14 is provided in the memory part 11 of the ECU 10, and a ROM data rewrite device 60 as an external device is connected to the communication bus 50. In such a LAN system for a vehicle, test signals are transmitted and received at the different communication speeds between the ECU 10 and the ROM data rewrite device 60 and one communication speed is selected from the different communication speeds based on the transmitted and received results of the test signals. The ECU 10 receives data for rewrite from the ROM rewrite device 60 at the selected communication speed and rewrites the contents of the flash E<2> PROM 14 by the received data for the rewrite.</p> |
