ISO9141 & ISO14230 Communication

Developer topics relating to software that reflashes or modifes ECU code and data

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ISO9141 & ISO14230 Communication

Postby romstef » Sun Sep 07, 2008 4:42 pm

Hi Guys,
I don't know if I am posting this in the correct area, however,
I am trying to use a microcontroller to communicate with vehicle ECU via the ISO9141 & ISO14230 protocol but I need help. I am not in a position to purchase the relevant ISO document. And I understand, it is not an easy read.

1/ I would like to know how to calculate the CHECKSUM for these protocol. E.g. I saw the foll. example for ISO9141, but can't figure it out;
REQUEST: 68h 6Ah F1h 01h 05h & 63h as checksum.
RESPONSE: 48h 6Bh 10h 41h 05h 44h & BBh as checksum. Help here please. Also, how would I do the calculation for ISO14230?

2/ Also, in order to communicate via the ISO9141 protocol, would I send only 68h 6Ah F1h 01h 05h & the CHECKSUM, or would I need to send more bytes?

3/ Last question; How would I determine the LENGTH BYTE in the ISO9141 protocol? I would be very grateful for an example.

Thanks very much guys. :?:
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