C#串口通信触发不了DataReceived事件

public void SerialPort1_DataReceived(object sender, SerialDataReceivedEventArgs e)  //接收中断
        {
            int receive_length = SerialPort1.BytesToRead;
            byte[] receive_data = new byte[receive_length];
            //receive_data = Convert.FromBase64String(SerialPort1.ReadLine());
            //txt_receive.Text = Encoding.Unicode.GetString(receive_data);
            SerialPort1.Read(receive_data, 0, receive_length);
         
                string str = "";
                for (int i = 0; i < receive_length; i++)
                {
                    str += receive_data[i].ToString("X2") + " ";
                }
                this.Invoke(interfaceUpdateHandle, new string[] { str });
        }
  private void SerierCom_Load(object sender, EventArgs e)
        {
            //默认串口值
            combobox_com.SelectedIndex = 0;
            combobox_baudrate.SelectedIndex = 3;
            combobox_verify.SelectedIndex = 1;
            combobox_databit.SelectedIndex = 0;
            combobox_stopbit.SelectedIndex = 0;

            SerialPort1.PortName = "COM1";
            SerialPort1.BaudRate = 9600;
            SerialPort1.Parity =
            SerialPort1.Open();
            //public event HandleInterfaceUpdateDelegate SerialPort1_DataReceived;
            SerialPort1.DataReceived += new SerialDataReceivedEventHandler(SerialPort1_DataReceived);//注册事件
            //HandleInterfaceUpdateDelegate interfaceUpdateHandle = new HandleInterfaceUpdateDelegate(UpdateTextBox);
            //Control.CheckForIllegalCrossThreadCalls = false;//屏蔽非法跨线程调用将始终引发异常
            SerialPort1.ReceivedBytesThreshold = 1;
            //thread1 = new Thread(new ThreadStart(UpdateTextBox));
            //thread1.Start();
        }