Can Bus flow control - automotive

02 Feb 2011

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.


03 Feb 2011

What protocol?

CANOpen, J1939, proprietry?

05 Feb 2011

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.


20 Feb 2011


20 Feb 2011

Presumably you've seen this: ?

20 Feb 2011

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.

21 Feb 2011

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 Web

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