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<p>Heya,</p>
<p>I'm back from my 2 hr VCDS session... not satisfying at all...</p>
<p><b>Car-off polling issue:</b><br>
VCDS lists me 19 ECUs (with the ignition on) which includes 09
"Zentralelektrik" (which Michael recommended), 19
"Diagnosteinterface" and 61 "Batterieregelung" which stay
responsive for a period of time after ignition is off. All other
are not responsive no more with no ignition...<br>
But: Once the car is locked not a single ECU is responding :( . So
there is nothing to poll which will respond in any state of the
car.<br>
The only option is the +12V on pin 1. <u>Is pin 1 somehow
connected to OVMS via the standard OBD adapter?</u></p>
<p><b>Sniffing VCDS (+CarScanner App) commands:</b><br>
Here I'm somehow confused now. I've tried to sniff the header/txid
of ECU 61 (Betterieregelung) as the list of sharkcow hasn't it
listed yet. It seems that the header is not transmitted, neither
in VCDS nor in CarScanner. Only the PID goes to the OBD port. To
understand the transmissions I've tried in CarScanner to swap
between two dashboards/value-readings. One for SoC (=22 02 8C) of
ECU 8C (header=7E5) outside-temp (=22 F4 46) of ECU 01
(header=7E0).<br>
I couldn't find any 7E5 or 7E0 in the sniffed data!? Why? How is
the ECU addressed then? I've also think of any rule to get from
the ECU number (i.e. 8C, 01) to the header, but couldn't find
any...</p>
<p><b>Scan for OBD devices:</b><br>
Thanks for the info & details Michael. But is there a chance
that I'll find an OBD device which VCDS doesn't know about (or
doesn't list in the software)?<br>
If yes: Can I somehow put this manual request in C++ code instead
of using the shell? Then I don't have to type this manually 256
times (by using a loop) ;)<br>
Also, is there a typo in your email? You write "...sent to ID 700,
type..." but the command says "79b" and later you write "...there
is a device listening at 79b...". So is ID 700 the device 79b or
did you mean ID 79B?</p>
<p>thx for you patience with me</p>
<p>Soko<br>
</p>
<div class="moz-cite-prefix">On 31.07.2020 14:09, Michael Balzer
wrote:<br>
</div>
<blockquote type="cite"
cite="mid:d632962a-65c8-1083-1569-4c192fdaa71b@expeedo.de">
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
Soko,<br>
<br>
you don't need to use the poller to scan for OBD devices. You can
simply do manual transmissions and look for responses.<br>
<br>
To send a manual request, simply use the can tx command. Example:<br>
<br>
<tt>OVMS# can can1 tx standard 79b 02 01 00 00 00 00 00 00</tt><br>
<br>
This means: 2 byte OBD request sent to ID 700, type 01 = get
current data, from PID 00. PID 00 is supposed (OBD-II) to reply
with a four byte bitset of the device's PIDs 01-20 (hex) support.<br>
<br>
Send this with can logging enabled without filters, so you can see
all responses. A response could look like this:<br>
<br>
<tt>V (591792) canlog-monitor: 1596194327.716686 1R11 7BB 03 7f 01
11 00 00 00 00</tt><br>
<br>
This tells you:<br>
<ul>
<li>there is a device listening at 79b, which answers at 7bb --
nice!<br>
</li>
<li>it probably talks ISO-TP -- nice!</li>
<li> it won't allow you to do this request in it's default
session: 7F = serviceNotSupportedInActiveSession<br>
</li>
</ul>
OK, let's try to change the session (command 10) to the ISO 14229
standard "extendedDiagnosticSession" (value 03):<br>
<br>
<tt>V (2085712) canlog-monitor: 1596195821.642256 1T11 79B 02 10
03 00 00 00 00 00</tt><tt><br>
</tt><tt> V (2085722) canlog-monitor: 1596195821.659737 1R11 7BB
03 7f 10 12 00 00 00 00</tt><br>
<br>
No luck. You can now begin trying all possible session codes. Or,
in my case, I already know the device uses C0 ;-)<br>
<br>
<tt>V (2095662) canlog-monitor: 1596195831.598560 1T11 79B 02 10
c0 00 00 00 00 00</tt><tt><br>
</tt><tt> V (2095672) canlog-monitor: 1596195831.609308 1R11 7BB
02 50 c0 00 00 00 00 00</tt><tt><br>
</tt><tt> </tt><br>
We're logged in -- nice! :-)<br>
<br>
Let's try the PID read again (do this within 60 seconds or the
session will log out, unless you send a "tester present" frame):<br>
<br>
<tt>V (2530842) canlog-monitor: 1596196266.780867 1T11 79B 02 01
00 00 00 00 00 00</tt><tt><br>
</tt><tt>V (2530862) canlog-monitor: 1596196266.797961 1R11 7BB 03
7f 01 11 00 00 00 00</tt><br>
<br>
Still no luck. So this tells you, the device does not support
standard OBD-II PIDs. How about a UDS DTC request (19)?<br>
<br>
<tt>V (3034142) canlog-monitor: 1596196770.085839 1T11 79B 02 19
01 ff 00 00 00 00</tt><tt><br>
</tt><tt>V (3034162) canlog-monitor: 1596196770.103517 1R11 7BB 03
7f 19 12 00 00 00 00</tt><br>
<br>
No luck. Let's try command 21 (read enhanced data by 8 bit PID) at
PID 00 next:<br>
<br>
<tt>V (2737632) canlog-monitor: 1596196473.567437 1T11 79B 02 21
00 00 00 00 00 00</tt><tt><br>
</tt><tt>V (2737712) canlog-monitor: 1596196473.649927 1R11 7BB 03
7f 21 12 00 00 00 00</tt><br>
<br>
Nope… maybe PID 01?<br>
<br>
<tt>V (2744182) canlog-monitor: 1596196480.120911 1T11 79B 02 21
01 00 00 00 00 00</tt><tt><br>
</tt><tt>V (2744262) canlog-monitor: 1596196480.203461 1R11 7BB 10
34 61 01 13 88 13 83</tt><br>
<br>
Houston, we've got a response :-)<br>
<br>
You would now check if this response is a single or multi frame
type, then try to get all data and then try to map the data to
something you would expect to be stored in that device.<br>
<br>
For the standard UDF commands, you will need a copy of the ISO
14229 standard.<br>
<br>
Regards,<br>
Michael</blockquote>
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