private void serialPort1_DataReceived(object sender, SerialDataReceivedEventArgs e)
        {
            SerialPort sp = (SerialPort) sender;
            if (sp.BytesToRead < INCOMING_CMD_LENGTH) return;
            string cmd = sp.ReadLine();
            System.Console.Write(cmd);
            Invoke(new Action(() => { textBoxLastCommand.Text += cmd; }));
            if (cmd.Equals("test")) System.Console.Write("OK");
        }