给我一个Winform的串口调试助手的示例

下面是一个Winform串口调试助手的示例代码，可以实现串口的打开、关闭、发送数据、接收数据等操作：

using System;
using System.IO.Ports;
using System.Windows.Forms;

namespace SerialPortDemo
{
    public partial class Form1 : Form
    {
        private SerialPort serialPort;

        public Form1()
        {
            InitializeComponent();

            // 初始化串口
            serialPort = new SerialPort();
            serialPort.DataReceived += new SerialDataReceivedEventHandler(serialPort_DataReceived);
        }

        private void btnOpen_Click(object sender, EventArgs e)
        {
            // 打开串口
            try
            {
                serialPort.PortName = cbPortName.SelectedItem.ToString();
                serialPort.BaudRate = Convert.ToInt32(cbBaudRate.SelectedItem.ToString());
                serialPort.DataBits = Convert.ToInt32(cbDataBits.SelectedItem.ToString());
                serialPort.Parity = (Parity)Enum.Parse(typeof(Parity), cbParity.SelectedItem.ToString());
                serialPort.StopBits = (StopBits)Enum.Parse(typeof(StopBits), cbStopBits.SelectedItem.ToString());
                serialPort.Open();
                btnOpen.Enabled = false;
                btnClose.Enabled = true;
                btnSend.Enabled = true;
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
            }
        }

        private void btnClose_Click(object sender, EventArgs e)
        {
            // 关闭串口
            try
            {
                serialPort.Close();
                btnOpen.Enabled = true;
                btnClose.Enabled = false;
                btnSend.Enabled = false;
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
            }
        }

        private void btnSend_Click(object sender, EventArgs e)
        {
            // 发送数据
            try
            {
                if (serialPort.IsOpen)
                {
                    serialPort.Write(txtSend.Text);
                }
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
            }
        }

        private void serialPort_DataReceived(object sender, SerialDataReceivedEventArgs e)
        {
            // 接收数据
            try
            {
                string data = serialPort.ReadLine();
                this.Invoke(new EventHandler(delegate
                {
                    txtReceive.AppendText(data);
                }));
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
            }
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            // 初始化串口参数
            string[] portNames = SerialPort.GetPortNames();
            cbPortName.Items.AddRange(portNames);
            cbPortName.SelectedIndex = 0;
            cbBaudRate.SelectedIndex = 2;
            cbDataBits.SelectedIndex = 1;
            cbParity.SelectedIndex = 0;
            cbStopBits.SelectedIndex = 0;
            btnClose.Enabled = false;
            btnSend.Enabled = false;
        }
    }
}

该示例中，使用了四个按钮分别实现打开串口、关闭串口、发送数据和清空接收区的功能。在串口接收到数据时，将数据显示在接收区中。同时也可以设置串口的参数，例如波特率、数据位、校验位、停止位等。