请问串口通讯DataReceived事件不触发的有关问题

public SerialPort serialPort2;

        delegate void HandleInterfaceUpdateDelegate(string text);  
        HandleInterfaceUpdateDelegate interfaceUpdateHandle;

        public Form1()
        {
            InitializeComponent();
            InitCOM("COM1");
        }
        
        /// <summary>
        /// 串口接收通信配置方法
        /// </summary>
        /// <param name="PortName"></param>
        public void InitCOM(string PortName)
        {
            interfaceUpdateHandle = new HandleInterfaceUpdateDelegate(UpdateTextBox);  //实例化委托对象 
            serialPort2 = new SerialPort(PortName, 2400, Parity.Odd, 8, StopBits.One);
            serialPort2.DataReceived += new SerialDataReceivedEventHandler(serialPort2_DataReceived);//DataReceived事件委托
            serialPort2.ReceivedBytesThreshold = 1;
            serialPort2.RtsEnable = true;
            OpenPort();
            label1.Text = label1.Text+serialPort2.PortName;
            label2.Text = label2.Text + serialPort2.BaudRate.ToString();
            label3.Text = label3.Text + serialPort2.DataBits.ToString();
            label4.Text = label4.Text + serialPort2.StopBits.ToString();
            label5.Text = label5.Text + serialPort2.Parity.ToString();

        }

        /// <summary>
        /// 数据显示方法
        /// </summary>
        /// <param name="text"></param>
        private void UpdateTextBox(string text)
        {
            textBox1.Text = text;
        }
        
        /// <summary>
        /// 数据接收事件
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void serialPort2_DataReceived(object sender, SerialDataReceivedEventArgs e)
        {
            Thread.Sleep(2000);
            byte[] readBuffer = new byte[serialPort2.ReadBufferSize];
            serialPort2.Read(readBuffer, 0, readBuffer.Length);
            this.Invoke(interfaceUpdateHandle, new string[] { Encoding.UTF8.GetString(readBuffer, 0, 100) });
        }

        //public static string ByteArrayToHexString(byte[] data)//字节数组转为十六进制字符串
        //{
        //    StringBuilder sb = new StringBuilder(data.Length * 3);
        //    foreach (byte b in data)
        //        sb.Append(Convert.ToString(b, 16).PadLeft(2, '0').PadRight(3, ' '));
        //    return sb.ToString().ToUpper();
        //}

        //打开串口的方法
        public void OpenPort()
        {
            try
            {
                serialPort2.Open();
            }
            catch { }
            if (serialPort2.IsOpen)
            {
                Console.WriteLine("the port is opened!");
            }
            else
            {
                Console.WriteLine("failure to open the port!");
            }
        }

        //关闭串口的方法
        public void ClosePort()
        {
            serialPort2.Close();
            if (!serialPort2.IsOpen)
            {
                Console.WriteLine("the port is already closed!");
            }
        }

        /// <summary>
        /// 窗体加载事件
        /// </summary>
        /// <param name="sender">事件参数</param>
        /// <param name="e">窗体</param>
        private void Form1_Load(object sender, EventArgs e)
        {

        }