If you are getting started to OBD-II protocol used for cars’ diagnostic, then you need to know the OBDSim simulator. If you want to know more about OBD-II I have posted some links here: http://acassis.tumblr.com/post/81403602911/mais-informacoes-sobre-obd-ii
It is different from others OBD-II simulators because you can emulate the ELM327 dongle interface and the car data. In fact it is a little confuse at start, but it is because this software is very powerful.
The easy way to get started is using the fltk GUI, this way:
$ obdsim -g Cycle -g gui_fltk -g Cycle SimPort name: /dev/pts/6 Successfully initialised obdsim, entering main loop
Please note it creates a virtual serial port (tty) to receive commands (using ELM327 standard) then use “minicom” or other serial console software to open /dev/pts/6 (I tested it configured to 115200 8n1).
Now you can send some commands:
>ATZ ELM327 v1.3a OBDGPSLogger >ATH1 OK >010D 7E8 03 41 0D 09 09
The above command will read the “Vehicle Speed” you defined in the gui_fltk interface. Just click on the pointer of Vehicle Speed and move it, then execute the “010D” to read the new speed.