I'm experimenting with reading the VIN number from my cars ECU. I have sucessfully retrieved the first three VIN characters however to my understanding I need to send a flow control frame / message to retrieve the remaining VIN characters since the VIN number is 17 characters (17 characters = 17 ascii coded bytes).

Does anyone know how or able to point me to some code which deals with flow control to handle multiple data frames i.e. greater than the single 8 byte payload I have already successfully read.

Thanks.

What protocol?

CANOpen, J1939, proprietry?

Hi Andrew

After a bit of research I believe that it is probably the J1939 protocol that I shall be needing to refer to.

This is part of my university project which up until now has been progressing reasonably well. I have been finding it difficult to find the relevant information.

If it's any help the car I'm connecting is a 2005 Ford Fiesta. If you are able to offer any pointers it would be much appreciated.

James.

bttt

Presumably you've seen this: http://en.wikipedia.org/wiki/OBD-II_PIDs ?

Yeh that is pretty much where I started from. There are a number of web pages / documents that refer to can bus flow control but the ones I have seen so far don't really ellaborate on the ins and outs of it or how to apply it.

The document that describes the flow control for automotive CAN is:

ISO 15765-2:2004(E) "Road vehicles — Diagnostics on Controller Area Networks (CAN) — Part 2: Network layer services"

You can purchase it from from the following the ISO organization at: ISO copyright office Case postale 56 • CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyright@iso.org Web www.iso.org

You may be able to find clips from it on the web or open source software that implements it.