private void connect()
        {
            string selectedPort = comboBox1.GetItemText(comboBox1.SelectedItem);

            Connection_window.Text = "";

            Connection_window.AppendText("Selected COM Port = " + selectedPort + Environment.NewLine);
            Connection_window.AppendText("Trying to open " + selectedPort + Environment.NewLine);
            try
            {
                isConnected = true;

                port.PortName = selectedPort;
                port.Open();
                string start = "#STAR\n";
                port.Write(start);
                port.ReadExisting();
                logTraffic(TX_traffic_window, start, Color.Black);
                connectBtn.Text = "Disconnect";
                Connection_window.AppendText("--------------------------------------" + Environment.NewLine);
            }
            catch
            {
                Connection_window.AppendText("Cannot open " + selectedPort + Environment.NewLine);
                return;
            }
            Connection_window.AppendText(selectedPort + " now open" + Environment.NewLine);
            Connection_window.AppendText("--------------------------------------" + Environment.NewLine);
        }
        private void disconnect()
        {
            try
            {
                isConnected = false;
                port.Write("#STOP\n");
                port.Close();
                connectBtn.Text = "Connect";
            }
            catch
            {
                return;
            }

            Connection_window.AppendText(port.PortName + " is now closed" + Environment.NewLine);
            Connection_window.AppendText("--------------------------------------" + Environment.NewLine);
        }