//Thread erzeugen bei neuer Verbindung          
  private void ListenForClients()
            {
                this.tcpListener.Start();

                while (true)
                {
                    //blocks until a client has connected to the server
                    TcpClient client = this.tcpListener.AcceptTcpClient();
                    AppendToRichEditControl("Neu verbunden: "+client.Client.RemoteEndPoint.ToString()+"\r" );
                    //create a thread to handle communication
                    //with connected client
                    Thread clientThread = new Thread(new ParameterizedThreadStart(HandleClientComm));
                    clientThread.Start(client);
                }
            }
        
//Messages bearbeiten
            private void HandleClientComm(object client)
            {
                TcpClient tcpClient = (TcpClient)client;
                NetworkStream clientStream = tcpClient.GetStream(); //todo stürzt ab beim vorzeitigen abschalten der CNC

                byte[] message = new byte[4096];
                int bytesRead;
                int sizeToGet;
                int cncId=0;
                Type_t type;
                Command_t command;
              
               
                while (true)
                {
                    bytesRead = 0;

                    try
                    {
                        //blocks until a client sends a message
                        bytesRead = clientStream.Read(message, 0, 4096);
                    }
                    catch
                    {
                        //a socket error has occured
                        AppendToRichEditControl("Station: " + cncId + " wg. SocketFehler nicht mehr verbunden\r");
                        break;
                    }

                    if (bytesRead == 0)
                    {
                        //the client has disconnected from the server
                        AppendToRichEditControl("Station: " + cncId + " nicht mehr verbunden\r"); 
                        break;
                    }
                    try
                    {
                        if (bytesRead >= 4)
                        {
                            type = (Type_t)message[0];
                            command = (Command_t)message[1];
                            sizeToGet = message[2] * 128 + message[3];
                            switch (command)
                            {

                                case Command_t.command_getProgramm:
 				    if (File.Exists(filenameRoot + "programm.dat"))
                                    {                                            
					    FileStream fileStream = new FileStream(filenameRoot + "programm.dat", FileMode.Open, FileAccess.Read);
                                            int length = (int)fileStream.Length;
                                            int totalLength = length + 5;
                                            
                                            byte[] outData;
                                            int totalLength = 5;
                                            int length = 0;
                                            outData = new byte[totalLength]; //1 byte mehr wegen ok in byte 5
                                            outData[0] = (byte)Type_t.type_serverAnswer;
                                            outData[1] = (byte)command;
                                            outData[2] = (byte)((length+1) / 128); //das Antwortbyte 4 braucht Platz
                                            outData[3] = (byte)((length+1) % 128);
                                            outData[4] = (byte)0;   //das ist dann ok
                                            //DAten aus Datei holen
					    fileStream.Read(outData, 5, length);
					    //Header + Daten ausgeben
					    clientStream.Write(outData, 0, totalLength); //todo stimmt hier sum
                                            clientStream.Flush();
                                        }
                                        else
                                        {
                                            //Fehlermeldung 2 erzeugen
                                            byte[] outData;
                                            outData = new byte[5]; //1 byte mehr wegen ok in byte 5
                                            outData[0] = (byte)Type_t.type_serverAnswer;
                                            outData[1] = (byte)command;
                                            outData[2] = (byte)(5 / 128);
                                            outData[3] = (byte)(5 % 128);
                                            outData[4] = (byte)2;   //das ist dann Fehler 2
                                            clientStream.Write(outData, 0, 5); //todo stimmt hier sum
                                            clientStream.Flush();
                                        }
                                    
                                    break;

                            }
                        }
                    }
                    catch (Exception e)
                    {
                        MessageBox.Show("Ende wegen Fehler: " + e.ToString());
                        tcpClient.Close();
                        break;
                    }
                    //message has successfully been received
                    ASCIIEncoding encoder = new ASCIIEncoding();
                    System.Diagnostics.Debug.WriteLine(encoder.GetString(message, 0, bytesRead));
                    //clientStream.Write(message,0,bytesRead);
                }

                tcpClient.Close();
            }