Engineers and programmers are often intimidated by the prospect of interfacing with OBD-II systems. Five protocols, a dozen modes, hundreds of parameters, thousands of trouble codes. Who can figure it all out? The good news is, tapping into the wealth of information available on the OBD bus is easier than you think. To get started, you will need three things: documentation, an OBD interface, and an ECU or a simulator.
The articles in this series assume that you are using an STN11xx-based OBD interface (OBDLink, microOBD, STN1110), although many of the examples will work with the older ELM327-based interfaces as well. An OBD interface, sometimes referred to as “OBD adapter”, is an digital device whose job is to convert OBD signals that the host system can understand, like UART or RS-232. A useful analogy is to think of the OBD interface as a modem.
In order to test your software, you will need to connect the interface to an OBD-compliant vehicle, a benchtop ECU, or an ECU simulator (highly recommended).