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Ah, ok. Thought we might be able to quickly force the
identification, but with the bridge, that won't work. Plus the
negative side effect. <br>
<br>
Greg<br>
<br>
<br>
<div class="moz-cite-prefix">Mark Webb-Johnson wrote:<br>
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cite="mid:E7FACCFC-909F-4BCE-9E13-6524E7D77AC7@webb-johnson.net">
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<div class="">I seem to remember that the leaf has a module that
bridges the two CAN buses. The issue was that if you poll on the
wrong bus when the car is asleep, it wakes up the car 12V
(clicking relay), does the poll, then goes back to sleep
(clicking relay).</div>
<div class=""><br class="">
</div>
<div class="">Better to use passively transmitted traffic. Perhaps
a flag is set to ignore incoming messages until the buses are
identified, then when the trigger can message is seen, the
arrangement of buses can be determined and the flag cleared.</div>
<div class=""><br class="">
</div>
<div class="">Regards, Mark.</div>
<div class=""><br class="">
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<blockquote type="cite" class="">
<div class="">On 6 May 2018, at 10:12 AM, Greg D. <<a
href="mailto:gregd2350@gmail.com" class=""
moz-do-not-send="true">gregd2350@gmail.com</a>>
wrote:</div>
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<div text="#000000" bgcolor="#FFFFFF" class=""> Hi Robin,<br
class="">
<br class="">
I'm guessing that the VIN might only be accessible on
one of the two CAN interfaces. Would that be sufficient
to determine which bus is which?<br class="">
<br class="">
Greg<br class="">
<br class="">
<br class="">
<div class="moz-cite-prefix">Robin O'Leary wrote:<br
class="">
</div>
<blockquote type="cite"
cite="mid:20180506005627.GA8337@mail.ro.nu" class="">
<pre class="" wrap="">On Tue, May 01, 2018 at 09:59:04PM +0800, Mark Webb-Johnson wrote:
</pre>
<blockquote type="cite" class="">
<pre class="" wrap="">Suggestion: Can the model year of the car be determined from the VIN?
We do that for a few other of the models.
</pre>
</blockquote>
<pre class="" wrap="">So in order to read the Leaf VIN and battery data, I had some fun getting
to know the ins and outs of ISO-TP and UDS so I could write my own packet
reassembler. Of course, it was only when I had it all working nicely that
it dawned on me that Mark's comment above meant that there was probably
already code for that somewhere that would have saved me the effort,
which there is, in OvmsVehicle::PollerReceive and IncomingPollReply. Duh!
But when I swapped over to using those methods, I got different
results---the first byte of the VIN was missing, and IncomingPollReply
never got called with ml_remain==0 for the much longer battery data.
So now I was glad that I had my own version for comparison, as it made
me more sure than I might otherwise have been that PollerReceive was
processing the first frame incorrectly. Indeed, I think it is doing
two things wrong: it starts reading data from byte 5 not byte 4, and it
gets the overall length wrong by 2 (this confusion is likely because the
length given in the ISO-TP layer includes the two UDS header bytes, but
the rest of the UDS processing expects those bytes not to be counted in
the data passed to IncomingPollReply). Fixing both of those made both
the Leaf VIN and battery data come out correctly. My changes are here:
<a class="moz-txt-link-freetext" href="https://github.com/caederus-ovms/Open-Vehicle-Monitoring-System-3/tree/leaf-poll" moz-do-not-send="true">https://github.com/caederus-ovms/Open-Vehicle-Monitoring-System-3/tree/leaf-poll</a>
That leads me to wonder how existing uses of this code haven't run in
to the same problems. It is used in at least two places that seem like
they should have been affected:
OvmsVehicleOBDII::IncomingPollReply
case 0x02: // VIN (multi-line response)
OvmsVehicleKiaSoulEv::IncomingVMCU
case 0x02: // VIN (multi-line response):
So could it be that the PollerReceive code is correct after all and that
I am misunderstanding how it works, maybe because there is something
odd about the Leaf? Could any developers knowledgable about the OBDII
interface and the Kia Soul see if my changes make things better or worse?
Thanks.
btw, I still don't know the answer to the original question of whether
the model year of the car can be determined from the VIN, but at least
we can now easily see what it is!
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