comport.ReadTimeout = 30;
            comport.ReceivedBytesThreshold = 5;
            comport.DataReceived += new SerialDataReceivedEventHandler(comport_DataReceived);

 private void send_Click(object sender, EventArgs e)
        {
            byte[] data = ASCIIEncoding.GetEncoding("gb2312").GetBytes(sdtext.Text.ToString());
            if (mycomm.IsOpen)
            {
                mycomm.Write(data,0,data.Length);
                mycomm.WriteLine("\r");
            }
        }
         
        //接收
        private void mycomm_DataReceived(object sender, System.IO.Ports.SerialDataReceivedEventArgs e)
        {
            int DataLength = mycomm.BytesToRead;//获取接受缓冲区中数据的字节数
            int i = 0;
            StringBuilder strb = new StringBuilder();
            while (i < DataLength)
            {
                byte[] dbs = new byte[2048];
                int len = mycomm.Read(dbs,0,2048);//从输入缓冲区中读取2048个字节，并将这些字节写入到dbs[]数组中
                strb.Append(ASCIIEncoding.GetEncoding("gb2312").GetString(dbs, 0, len));
                i += len;
            }
            revtext.Text += strb;
        }

------解决方案--------------------
我用的是 事件驱动模式，发送事件，把sdtext.Text的文本用gb2312的编码方式转换成字节码；
接受方，用while处理，把字节码用gb2312的编码方式解码成String字符串，再把字符串显示到revtext.Text 里！

------解决方案--------------------
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