c# 串口通信，

Question

c# 串口通信，打开串口报错：不支持请求

Answer 1

public event EventHandler<CardEventArgs> VipCardSlide;        private string _cardCache;
        private bool _enableReadCard;
        private readonly System.Timers.Timer _tmrVerifyCard;  
        readonly System.IO.Ports.SerialPort _serialCardReader;
       
        private readonly string _cardReaderPortName;
        public SerialCardReader()
        {
            //读卡参数
            _cardCache = string.Empty;
            _enableReadCard = true;            _tmrVerifyCard = new System.Timers.Timer();            _tmrVerifyCard.Elapsed += TmrVerifyCardElapsed;            _tmrVerifyCard.Interval = 1500;            _tmrVerifyCard.Enabled = false;            _cardReaderPortName ="COM3";
            _serialCardReader = new System.IO.Ports.SerialPort();
            _serialCardReader.DataReceived += SerialCardReaderDataReceived;
        }        public bool Open()
        {
            try
            {
                InitCardReaderPort();
                return true;
            }
            catch
            {
                return false;
            }
        }        public bool Reset()
        {
            try
            {
                return CloseCardReaderPort();
            }
            catch
            {
                return false;
            }
        }        public bool Close()
        {
            try
            {
                CloseCardReaderPort();
                return true;
            }
            catch
            {
                return false;
            }        }        //启动一个延时事件 
        //定时检查，异步
        private void TmrVerifyCardElapsed(object source, ElapsedEventArgs e)
        {
            _tmrVerifyCard.Enabled = false;            _enableReadCard = false;
            //string CardNumber = ReadCard.GetCardNumberFromCardCache(CardCache);
            //showInfo(CardCache);
            //TxtLogExecute.AddTxtLog(CardCache);            int splitor = _cardCache.IndexOf("=");
            if (splitor > -1)
            {
                string originalCache = _cardCache;
                _cardCache = _cardCache.Substring(0, splitor);
                string remainCache = originalCache.Substring(splitor + 1);                if(_cardCache.StartsWith("0"))                 {
                    splitor = remainCache.IndexOf("=");
                    if (splitor > -1)//
                        _cardCache = remainCache.Substring(0, splitor);
                    else                        _cardCache = _cardCache.Substring(9, 18);
                }
            }
            _cardCache = _cardCache.Trim('?');            if (_cardCache.Trim().Length > 0)
            {
                var handler = this.VipCardSlide;
                if (handler != null)
                {
                    //GoProgress();
                    //ShowTouchScreenEx("01");
                    //GoPageCall("01", "");
                    var ee = new CardEventArgs(NumberGenerationType.BankCard, _cardCache);
                    handler(this, ee);
                }
            }            _cardCache = string.Empty;
        }        #region 串口操作
        //初始化串口
        private bool InitCardReaderPort()
        {
            _serialCardReader.PortName = _cardReaderPortName;
            _serialCardReader.BaudRate =2400;
            _serialCardReader.Parity = System.IO.Ports.Parity.None;
            _serialCardReader.StopBits = System.IO.Ports.StopBits.One;
            _serialCardReader.Handshake = System.IO.Ports.Handshake.RequestToSend;
            _serialCardReader.DataBits = 8;
          
          //  _serialCardReader.ReadTimeout = 1000;
          //  _serialCardReader.WriteBufferSize = 2048;
            try
            {
                if (_serialCardReader.IsOpen)
                {
                    _serialCardReader.Close();
                    _serialCardReader.Open();
                }
                else
                {
                    _serialCardReader.Open();
                }
                return true;
            }
            catch
            {
                return false;
            }
        }