Nippondenso Co., Ltd.

Takahide Abe

Katsumi Takaba

Masahito Hyodo

Takehiro Abeta

In a communication system which ensures that a slave device can successively transmit a plurality of answer messages without causing collision with another message on a communication line, in response to a request message from a diagnosis tester, control devices transmit their answer messages in the order of their priorities, with a communication blank duration provided between answer messages. If any one of the control devices has first and second answer message to be transmitted successively, the control device transmits the second answer message a communication blank duration after completing transmission of the first answer message. The control device can thereby transmit the first and second answer messages before a control device of a lower priority starts to transmit its answer message. Message collision on the communication line is thus avoided.

Communication system for transmitting divisional messages back-to-back

A self-diagnosis apparatus for vehicle capable of storing sufficient data useful for abnormality diagnosis includes a control unit having a CPU and RAM which can hold its stored contents even at the time of cut-off of an ignition key. The CPU receives diagnosis data necessary for analysis of the abnormality of an equipment at each predetermined period and judges whether or not the value of the diagnosis data exists in a predetermined region, in order to count up a counter of a predetermined storage region beforehand provided in the RAM corresponding to the judged region. The counting-up is stopped when the abnormality of an equipment is detected. In contrast with a method in which the value of diagnosis data is stored into the RAM as it is, the range of change of a lot of diagnosis data until the generation of abnormality can be stored with a small memory size.

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Kariya, Japan

Takahide Abe