Port öffnen/schließen etc.
Code:
private void Form1_Load(object sender, EventArgs e)        {
            string[] ports = SerialPort.GetPortNames();
            comboBox1.Items.AddRange(ports);


            if (ports.Length > 0)
            {
                comboBox1.SelectedIndex = 0;
                btnOpen.Enabled = true;
            }
        }


        private void btnOpen_Click(object sender, EventArgs e)
        {
            if (btnOpen.Text == "Open")
            {
                serialPort1.PortName = comboBox1.Text;
                serialPort1.Open();
                btnOpen.Text = "Close";
                comboBox1.Enabled = false;
                groupBox1.Enabled = true;
                timer1.Enabled = true;
            }
            else
            {
                serialPort1.Close();
                btnOpen.Text = "Open";
                comboBox1.Enabled = true;
                groupBox1.Enabled = false;
                timer1.Enabled = false;
            }
        }
Daten rausschreiben
Code:
serialPort1.Write(dataSend.ToArray(), 0, dataSend.Count);
Daten empfangen
Code:
 // check for new data            
           while (serialPort1.BytesToRead > 0)
            {
                byte rxByte = (byte)serialPort1.ReadByte();


                protocol_ParseByte(rxByte);
            }
Sind nur Bruchstücke aus meinem Code, sollte aber alles nötige drin sein.

mfg