[Ovmsdev] ELM327 codes to

[Michael Balzer]

Soko,

0x22028C isn't a PID, it's an OBD2 command (0x22 = poll extended ID) +
the actual register address 0x028C to be polled.

And 0x7E5 isn't a header, it's probably the address of the OBD2 device
you're polling (txmoduleid) OBD2 is a subset of ISO-TP, in ISO-TP
devices can be addressed at any ID and respond at any ID. The OBD2 base
protocol defines a broadcast address at 0x7DF, and assigned device
addresses in the range 0x7E0 - 0x7E7. Replies shall be sent at the
device address + 8, so the reply for a poll to 0x7E5 would normally be
coming from 0x7ED (rxmoduleid).

That are the basic principles of the OBD2 protocol, see
https://en.wikipedia.org/wiki/OBD-II_PIDs#CAN_(11-bit)_bus_format .

So your poll could for example be defined as:

const OvmsVehicle::poll_pid_t vwup_poll[] = {
  // Note: poller ticker cycles at 3600 seconds = max period
  // { txid, rxid, type, pid, { period_off, period_drive, period_charge } }
  { 0x7E5, 0x7ED, VEHICLE_POLL_TYPE_OBDIIEXTENDED, 0x028C, { 0, 10, 60 } },
  { 0, 0, 0, 0, { 0, 0, 0 } }
};

See vehicle.h for OBD2 commands (poll types) currently supported. See
the other vehicles for examples of complex poll definitions.

Regards,
Michael


Am 25.07.20 um 20:09 schrieb Soko:
> Heya,
>
> Another thing I can't figure out at the moment. I have to poll the
> VWeUp and I figured out (hopefully) how to do that. But I have no clue
> how to translate the "usual" ELM327 Header+PID to one entry for the
> OvmsVehicle::poll_pid_t
>
> The only value I've understood is the polltime. On my OBD2 interfaces
> I use a PID of 0x22028C for SoC. But PID is here only 16 bit! Where do
> I put the header 7E5? What is txmoduleid and rxmoduleid?
>
> I can't believe that I'm the first one with this issue ;) Couldn't
> find any doc though :(
>
> So I'm very thankful for any pointing in the correct
> direction/doc/example.
>
> thanks
>
> Soko
>
>
>
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