connect to serial port and send/receive data

2.cs

private void connect_button_Click(object sender, EventArgs e)
{
...
    string port_name = portlist_comboBox.SelectedItem.ToString(); // get serial port name
    serial_port_ = new SerialPort(port_name, 9600);               // set port name and speed 9600 bits/second 

    serial_port_.Open(); // connect to port
    thread_ = new Thread(read_serial_port); // create thread for reading received data
    thread_.Start();
...
}
...
public void read_serial_port()
{
    while (serial_port_.IsOpen)
    {
        try
        {
            string str = serial_port_.ReadLine(); // 
            add_output(str); // add to output text box.
        }
        catch (TimeoutException) { }
    }
}
...
private void send_button_Click(object sender, EventArgs e)
{
    serial_port_.Write(send_textBox.Text);
    send_textBox.Clear();
}