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Thread: how to analyze KWP2000 data packet?

  1. #1
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    how to analyze KWP2000 data packet?

    Here is data packet received from vehicle, but I do not know how to analyze. Could anybody help me?

    The car is polo:

    82 10 F1 21 02 A6 //read channal 2 data
    9A F1 10 61 02 01 C8 00 21 85 85 0F 29 00 12 FA 58 25 00 00 25 00 00 25 00 00 25 00 00 22


    VAS-5053 tool display 4 data value:0、100%、0、880,but how to explain? Is there any parameter define document for my reference?

    Thanks very much for your help.

  2. #2
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    Quote Originally Posted by winterdu View Post
    Here is data packet received from vehicle, but I do not know how to analyze. Could anybody help me?

    The car is polo:

    82 10 F1 21 02 A6 //read channal 2 data
    9A F1 10 61 02 01 C8 00 21 85 85 0F 29 00 12 FA 58 25 00 00 25 00 00 25 00 00 25 00 00 22


    VAS-5053 tool display 4 data value:0、100%、0、880,but how to explain? Is there any parameter define document for my reference?

    Thanks very much for your help.
    If this is actually KWP 2000, then the packeting would follow ISO 14230-2, and the messaging ISO 14230-3.

    Let's see how that adds up. The first byte identifies the type of frame and the length (this can be set to 0, then there is another byte used for length later), but in this case, 82 hex would mean:

    10B for frame type (with addressing, physical addressing)
    000010B for length (2 data bytes)

    Since the length is not zero, and addressing is present, the next two bytes would represent:

    0x10 = Target
    0xF1 = Source (common for a test tool)

    The next two bytes, 21 02 would be the data bytes, 21 should be the service type.

    21 Hex falls into the range of a "request", because bit 6 = 0. In generic 14430-3, it means:

    readDataByLocalIdentifier

    The identifier would then be "02". If this is a read channel 2 request, then so far so good.

    The last byte, A6, should be a checksum of the packet. If we add the other bytes up, we get 0x1A6, which truncates to a byte checksum of A6, so the request looks good.

    Now the response:

    The first bytes again breaks down into a 'addressing/physical' (10B) packet, but the length is 26 (decimal), which matches the length minus addressing.

    F1 would then be the target (the test tool)
    10 would be the source (the module sent the request above)

    61 means a 'positive response' to request 21.

    The next byte, 02, is probably the address from the request, but not nec.

    The last byte, 22, is again, a checksum (and seems to match).

    The bytes in between the 61 and the 22 follow the generic pattern of id:value, but what exactly they mean in this case I could not really say.

    Good Luck,
    -jjf

  3. #3
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    where is ID defined?

    jfitzpat,Thank you very much for your reply.

    Now I know the structure of packet, it is important for me to analyze "The bytes in between the 61 and the 22 follow the generic pattern of id:value".

    Is there any document to describe which ID and value make up this packet? I guess many paramenter of vehicle should be defined, for example RPM, SPEED, fuel level ...

  4. #4
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    Quote Originally Posted by winterdu View Post
    jfitzpat,Thank you very much for your reply.

    Now I know the structure of packet, it is important for me to analyze "The bytes in between the 61 and the 22 follow the generic pattern of id:value".

    Is there any document to describe which ID and value make up this packet? I guess many paramenter of vehicle should be defined, for example RPM, SPEED, fuel level ...
    I believe it is a Volkswagen specific protocol. VW's at least used to use their own variation of a keyword protocol (KWP1281), which people referred to as "VAG". There is quite a bit floating around the internet, but it is generally in snippets like these:

    http://hex.co.za/vaginfo/

    There is also a mail list called OpenDiag that used to do a lot of work on VW's.

    I don't know if the content above is VAG or not, but VAG focussed folks could probably tell you.

    Good Luck,
    -jjf

    Edit: Now that I look at it again, I would say 'not'. Presumably newer VW's have a vendor specific protocol based on KWP2000, but the meaning of the reads is still, typically, vendor specific.

  5. #5
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    jfitzpat,Thanks

    Could you tell me where CAN i get KWP1281 protocol.

    Thanks again

  6. #6
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    Quote Originally Posted by winterdu View Post
    jfitzpat,Thanks

    Could you tell me where CAN i get KWP1281 protocol.

    Thanks again
    First, it doesn't look like KWP1281, but something newer, based on KWP2000.

    Second, I'm sorry, I can't. I did a little searching this morning and couldn't really find much other than other people asking about the new KWP2000 based protocol.

    It might be available via the Equipment and Tool Institute (ETI), but you'd want to inquire before shelling out for membership.

    A lot of people rent factory tools, or other vendor tools, and reverse engineer the communication that way. That might be an option for you.

    Sorry I couldn't be of more help.
    -jjf

  7. #7
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    jfitzpat,Thanks for your patient.

    It is very lucky for me to heard your answer.

  8. #8
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    It was nothing. I'm sorry I couldn't be more helpful.

    -jjf

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