Most vehicles nowadays are equipped with board computers permanently controlling the state of internal vehicle components, performing tests and storing current vehicle data and failures. These board computers are accessable through the OBD port commonly located at the driving cab in the near of the clutch. obd2NET is a .NET libarary for querying these OBD systems. Real time data and diagnostic codes can be retrieved by performing simple serial requests. Basically, querying works just as simple: You cast the query mode (i.e. 0x01 for the current data) and specify a PID (parameter ID) such as 0x0D for the vehicle speed to get your information back. See OBD-II PIDs for available modes and PIDs.

However, when using this library, you don't need to worry on how to communicate with the vehicle, just plug in the OBD connector into your vehicle's OBD port and get the other end of the cable to communicate with your device (USB/serial interfaces).

Opening the connection is as easy as it gets:

IOBDConnection conn = new SerialConnection("COM5"); // you may need to replace the COM port

Getting the current (real-time) speed of the vehicle given in km/h:

uint speed = Vehicle.Speed(conn);

Obtaining available DTCs (Diagnostic Trouble Codes)

var networkTroubleCodes = Vehicle.DiagnosticTroubleCodes(conn).Where(code => code.ErrorLocation == DiagnosticTroubleCode.Location.Network);

foreach (var code in networkTroubleCodes)
    Console.WriteLine(code.TextRepresentation);

The given code will query all network trouble codes and print its text representation to the screen.

These are not all possibilities of the library, refer to the Vehicle class to get all implemented functions that query data. Please note that I only have tested these functions in my Audi A3 (2007) and can therefore not guarantee, that they will work for you.

Of course, not all vehicles around are implementing the ISO 9141 standard so this library might not work for your vehicle. Before OBD2, interfaces were manufacturer specific implemented so you'd rather look into your manufacturers implementation details and extend the library by yourself.

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