private SerialPort com;
        private void FormCheck_Load(object sender, EventArgs e)
        {
            //初始化COMList
            initCOMList();     
        }

        #region
        private void initCOMList()
        {
            ManageCOM com = new ManageCOM();
            List<string> s = com.AutoGetCOM();

            string[] comNames = s.ToArray();
            comboxCOM.Items.Clear();
            comboxCOM.Items.Add("請選擇COM");
            comboxCOM.SelectedIndex = 0;
            foreach (string portName in comNames)
            {
                //添加COM口到界面下拉框
                comboxCOM.Items.Add(portName);
            }
        }
        #endregion

        private void btnStart_Click(object sender, EventArgs e)
        {

            getWeightfromCOM();
        }

        #region
        private void getWeightfromCOM()
        {
            int selectIndex= comboxCOM.SelectedIndex;

            if (selectIndex!=0)
            {
                string COM = comboxCOM.Items[selectIndex].ToString();

                com = new SerialPort(COM);       //實例化SerialPort并設置COM口
                com.BaudRate = 9600;//波特率
                com.Parity = Parity.None;//無奇偶校驗位
                com.StopBits = StopBits.Two;//兩個停止位
                com.Handshake = Handshake.RequestToSend;//控制協(xié)議
                com.ReceivedBytesThreshold = 13;//設置 DataReceived 事件發(fā)生前內部輸入緩沖區(qū)中的字節(jié)數(shù),我這里是13字節(jié)為一組
                com.Open();                 //打開串口  
                com.DataReceived += new SerialDataReceivedEventHandler(Com_DataReceived);           //接受數(shù)據(jù)線程
            }
            else
            {
                MessageBox.Show("請選擇COM");
            }
            
        }

        /// <summary>
        /// 監(jiān)聽串口數(shù)據(jù)線程
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void Com_DataReceived(object sender, SerialDataReceivedEventArgs e)
        {
            Thread.Sleep(500);//線程休眠500毫秒，方便接收串口的全部數(shù)據(jù)
            try
            {
                if (com.IsOpen)
                {
                    byte[] readBuffer = new byte[com.ReadBufferSize + 1];
                    try
                    {
                        int count = com.Read(readBuffer, 0, com.ReadBufferSize);        //讀取串口數(shù)據(jù)(監(jiān)聽)
                        String SerialIn = System.Text.Encoding.ASCII.GetString(readBuffer, 0, count);//將字節(jié)數(shù)組解碼為字符串
                        if (count != 0)
                        {
                            //這里強調一下,線程里不可以直接對UI進行賦值，只能使用委托操作控件
                            this.BeginInvoke(new System.Threading.ThreadStart(delegate ()
                            {
                                rbResult.Text = SerialIn;
                            }));

                        }
                    }
                    catch (TimeoutException) { }
                }
                else
                {
                    TimeSpan waitTime = new TimeSpan(0, 0, 0, 0, 50);
                    Thread.Sleep(waitTime);
                }
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.ToString());
            }
        }
        #endregion