串口通信中，解决serialport.DataReceived接收到的数据不完整

        private SerialPort serialport = new SerialPort();
        private StringBuilder builder = new StringBuilder();
       // private StringBuilder bs = new StringBuilder();//用于存储一条完整信息;
        Boolean ope = false;

        public Form1()
        {
            InitializeComponent();
            Control.CheckForIllegalCrossThreadCalls = false;
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            string[] names = SerialPort.GetPortNames();
            if (names == null)
            {
                MessageBox.Show("没有可用的串口", "提示");
            }
            else
            {
                foreach (string str in names)
                {
                    toolStripComboBox2_Potrs.Items.Add(str);
                }
            }
            toolStripComboBox1_Rate.Text = "9600";
            toolStripComboBox1_Rate.Items.Add("4800");
            toolStripComboBox1_Rate.Items.Add("9600");
            //添加事件注册
            serialport.DataReceived += new SerialDataReceivedEventHandler(serialPort_DataRecived);



        }

        void serialPort_DataRecived(object sender, SerialDataReceivedEventArgs e)
        {
            Thread.Sleep(500);
            builder.Clear();//清除字符串构造器的内容
            string str = "";
            int n = serialport.BytesToRead;//先记录下来，避免丢失
            label3.Text = n.ToString();
            
            byte[] buf = new byte[n];
            serialport.Read(buf, 0, n);//读取缓冲区数据
            
            this.Invoke((EventHandler)(delegate
            {
                if (checkBox1_Hex.Checked)
                {
                    foreach (byte b in buf)
                    {
                        builder.Append(b.ToString("X2") + " ");
                        
                    }
                }
                else
                {
                    //直接以ASCII规则输出
                    builder.Append(Encoding.ASCII.GetString(buf));
                  //  bs.Append(Encoding.ASCII.GetString(buf));

                }
                //追加文本
                this.textBox1_ReciMes.AppendText(builder.ToString());
                //create a new thread
                //;
                Thread t = new Thread(new ParameterizedThreadStart(Options));
                Console.WriteLine(builder.ToString());
                t.Start(builder.ToString());
            }));
            
        }