SML Parser

This project implements the most common operations of the SML specification in. There are plenty of implementations, but I did not find one in c#, so I created one.

See details for the specification here: Spec

A list of implementstions in other languages is available on the Wikipedia page: https://de.wikipedia.org/wiki/Smart_Message_Language

The specification describes the communication with smart meters in order do receive values of counters as well as current load.

It is designed to work with a continous binary steam as well as just parsing a byte array.

Usually the smart meter is connected using an optical interface which transforms infra red signals into a serial byte stream that is read for example using an USB/serial converter.

Usage example for reading a byte array:

var file = @"SML-Message-20201128-234507.227.bin";
byte[] SML;
using (var f = new FileStream(file, FileMode.Open))
{
    SML = new byte[f.Length];
    f.Read(SML, 0, SML.Length);
}
var p = new SMLParser.SMLParser(SML);
List<SMLMessage> document = p.Parse();

Usage example for stream reading:

Given that you have connected the Smart meter to the Serial Port COM1, you can define an event handler whenever a complete SML message was received:

private const int BaudRate = 9600;
private const Parity PortParity = Parity.None;
private const int DataBits = 8;
public static void Main(string[] args)
{

    try
    {
        var port = new SerialPort("COM1", BaudRate, PortParity, DataBits);
        var mp = new MessagePipe("Home");
        mp.DocumentAvailable += MessagePipe_DocumentAvailable;
        MessagePipes.Add(port.PortName, mp);
        port.DataReceived += P_DataReceived;
        port.Open();
    }
    catch (IOException ex)
    {
        Console.Writeline($"While instancing the specified port the following Error occured: {ex.Message}");
        return;
    }
}

private static void MessagePipe_DocumentAvailable(object sender, SMLDocumentEventArgs e)
{
    var meterId = ((MessagePipe)sender).PipeName;
    Console.WriteLine("Received document in pipe '" + meterId + "'");
    var obis180Entry = ((SMLGetListResponse)e.Document[1].Body).ValList.Where(m => m.ObisCode != null && m.ObisCode.Register == "1-0:1.8.0*255").FirstOrDefault();
    Console.WriteLine($"Purchased energy total: {obis180Entry.UIntValue.Value / 10}");
    ((MessagePipe)sender).Reset();
}

private static void P_DataReceived(object sender, SerialDataReceivedEventArgs e)
{
    var p = (SerialPort)sender;
    byte[] chunk = new byte[p.BytesToRead];
    try
    {
        p.Read(chunk, 0, chunk.Length);
        MessagePipes[p.PortName].AddChunk(chunk);
    }
    catch (Exception Ex)
    {
        Console.Writeline("Error during reading bytes from Serial port. Resetting Pipe.");
        MessagePipes[p.PortName].Reset();
    }
}

The smart meter will continously send bytes which form a series of SML documents. The bytes are collected using the P_DataReceived event handler (This is part of the SerialPort Class of .Net). The chunk of bytes is handed over to the MessagePipe class which identifies the boundaries of SML Messages and will fire the MessageAvailable whenever a complete message is available, and returns an object which contains all the register values. A List of common registers can be found by loking into the ObisCodes.cs file.

The implementation of the spec is not complete (See th RawConvert.cs file for missing parsers) but it is good enough to read from a smart meter even with the extended information activated.