'response'에 해당되는 글 1건
- 2009.01.14 CAN Bus format Query - Response
The PID query is sent to the vehicle on the CAN bus at ID 7DFh, using 8 data bytes. The bytes are:
| Byte -> | _ 0 _ | _ 1 _ | _ 2 _ | _ 3 _ | _ 4 _ | _ 5 _ | _ 6 _ | _ 7 _ |
|---|---|---|---|---|---|---|---|---|
| SAE Standard | Number of additional data bytes: 2 |
Mode 01 = show current data; 02 = freeze frame; etc. |
PID code (e.g.: 05 = Engine coolant temperature) |
not used (may be 55h) |
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| Vehicle specific | Number of additional data bytes: 3 |
Custom mode: (e.g.: 22 = enhanced data) | PID code (e.g.: 4980h) |
not used (may be 00h or 55h) |
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Reponse
The vehicle responds to the PID query on the CAN bus with two messages, at IDs 7E8h and 7E9h. For standard (SAE) messages, the two messages are identical. For vehicle specific messages, they differ. Even though the number of bytes in the returned value is variable, the message uses 8 data bytes regardless. The bytes are:
| Byte -> | _ 0 _ | _ 1 _ | _ 2 _ | _ 3 _ | _ 4 _ | _ 5 _ | _ 6 _ | _ 7 _ |
|---|---|---|---|---|---|---|---|---|
| SAE Standard 7E8h and 7E9h or 7EAh |
Number of additional data bytes: 3 to 6 |
Custom mode Same as query, except that bit 6 is set. So: 41 = show current data; 42 = freeze frame; etc. |
PID code (e.g.: 05 = Engine coolant temperature) |
value of the specified parameter, byte 0 | value, byte 1 (optional) | value, byte 2 (optional) | value, byte 3 (optional) | not used (may be 00h or 55h) |
| Vehicle specific 7E8h |
Number of additional data bytes: 3 to 6 |
Custom mode: same as query, except that bits 5 and 6 are set.(e.g.: 62 = response to mode 22 request) | PID code (e.g.: 4980h) |
value of the specified parameter, byte 0 | value, byte 1 (optional) | value, byte 2 (optional) | value, byte 3 (optional) | |
| Vehicle specific 7E9h |
Number of additional data bytes: 3 |
7Fh | Custom mode: (e.g.: 22 = enhanced diagnostic data) | 31h | not used (may be 00h) |
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