Python OBD programming.

With the OBD2/OBDII port on most cars (all cars since 2001 sold in the US/Europe), in combination with an ELM327 based OBD2 to rs232/usb converter one can check some valus in the car's computer.

One nice program to do that is pyobd from OBDTester.com/SECONS. However, the latest version available from their website (0.9.2-2, as of 2011-01-28) has a number of bugs that make it impossible to use (at least for me). As it is GPL, I've made a patch that makes it more usable, see below.

A much simpler program to do the OBD2 comummunication is a text-only program I wrote, obdtour, for the source code, see below.

PyOBD

The pyobd 0.9.2-2 source code from OBDTester.com has a few shortcommings. So, below is a patch and a .tar.gz file that har the following changes:cd

• made the baud-rate configurable
• fixed bugs related to the import obd2_codes import of pcodes etc (trouble code lookup works again)
• I altered the serial-read code, it's now in a thread. This way the reading doesn't miss anything (even if the send_cmd() isn't immediately followed by get_result().
• The __init() function of class OBDPort expected a "BUSINITL ...OK" response, that isn't mentioned in the ELM327DS.pdf documentation, and isn't issued by my ELM327 v1.4. so, I made that response optional (and checked the real 0101 response).

• The patch file pyobd-0.9.2-2.patch (should be applied with the patch programme against the pyobd-0.9.2-2 source)
• Or, the full tar source file pyobd-0.9.2-2-joost-witteveen.tar.gz is here.

OBDTour

Before I fixed the PyOBD code, I experimented with a much simpler python OBD program, obdtour

• subversion access dir: svn co https://muso.komputilo.org/efsimul/trunk/obdtour
• a full tar file: obdtour-0.0.tar.gz

How to use obdtour: Currently, there's only one way to use it: you start it, and obdtour will check all supported OBD calls, and log the results in the file 'tour.log'.

Written by Joost Witteveen, joosteto at gmail.com; copyright: GPL
Other pages: SFT-2000 satellite receiver and Dimage Z2 camera.