[Ovmsdev] ODB CAN message decoder?

[Greg D.]

Hi Tom,

Ok, yes, wireshark does the decode of the CAN header, and that appears
to be functioning properly.  (candump and wireshark do agree on the
results, by the way.)  What I was after was a full decode, including
what the IDs represent, the PIDs being reported, and so forth.  As you
demonstrate, this is a non-trivial task, given the vehicle dependency,
but I was hoping the standard stuff would be shown.

I did find a Edit / Preferences / Protocols item on Wireshark for the
CAN protocol to select the "next level dissector".  Choices are Raw,
CANopen, DeviceNet, and J1939.  Default is Raw, with no further
dissection.  I was hopeful that J1939 would yield results, but it seems
a bit confused.  CANopen and DeviceNet are for factory stuff, and don't
apply.  J1979 is apparently what I need, and that (of course) is not one
of the choices.  Digging further...

Will look at your dissector further, thanks.  I'm not quite there yet,
but am making slow progress.

Thanks for the help,

Greg


Tom Parker wrote:
> On 08/02/17 19:28, Greg D. wrote:
>> I've looked, and could not find any Wireshark dissectors for CAN
>> messages. I also found one reference saying that there weren't any...
>
> The version of wireshark shipped with Ubuntu version of Wireshark
> natively decode the headers of CAN messages. Your screenshot shows
> that yours does too.
>
> I wrote a dissector for the Nissan Leaf CAN bus. I'm fairly sure I'm
> doing it wrong (I can't search for values within packets for example)
> but it's good enough to be able to scroll through captures and see the
> decoded data. Have a look
> https://carrott.org/git/leaf-can-dissector.git/blob/HEAD:/leaf.lua
>
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