[Ovmsdev] Shell syntax to write a value

Michael Balzer dexter at expeedo.de
Thu Feb 25 15:51:53 HKT 2021


Am 25.02.21 um 00:15 schrieb didier at ernotte.com:
> I can easily read a PID value using the shell syntax in the web 
> browser : "obdii can1 request device 7e4 7ec 22ddd00" for example.
> I understand that "0x22" is used to read data by identifier, and I 
> read that "0x2E" would be used to write data by identifier but what 
> would be the correct syntax to write a value to a PID in the shell ? 
> or it is not possible yet ?

You can send any OBD request that fits into a single frame.

If 2E is the write command for your device & PID (there are others and 
even non standard ones), it's simply…

obdii can1 request device 7e4 7ec 2e<pid><value>

The poller doesn't yet support multi frame requests (only responses), so 
the max request length for standard addressing mode is 7 bytes, leaving 
4 bytes payload for a 16 bit PID command.

See ISO 15031 and ISO 14229 for standard OBD/UDS requests and responses.


Michael Balzer * Helkenberger Weg 9 * D-58256 Ennepetal
Fon 02333 / 833 5735 * Handy 0176 / 206 989 26

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