Two of the drive recorder functions of the engine control unit were extended. First, a function was added that can use the vehicle diagnostic tool to freely generate a conditional expression that will record snapshot data as well as to enable modification of the conditional expression. Several patterns of conditional expressions were prepared in advance so that they could be combined to generate the conditional expressions that assure the capability to record the desired phenomena. Next, the system was configured to allow the snapshot data to be transmitted to a server external to the vehicle. The wireless network functionality of the Display Audio unit is used for transmission to the server, and the snapshot data is transmitted from the engine control unit to the Display Audio unit by divided transmission to enable the large volume of data to be handled for transmission between vehicle units, which are intended to handle small volumes of data. This was also done using simplex transmission in order to limit bus load increase on the transmission line. Measures were taken against data loss, as well, by providing for retransmission of the snapshot data even if the transmission is interrupted due to interruption of the power supply or other such reason.
Article of Honda R&D Technical Review Vol.27 No.1 (55 - 61)