2017.10.18更新：
1.加入停止顯示接收的字元。
2.加入定時傳送功能，可以迴圈傳送。
4.串列埠名稱支援漢字顯示，例如:COM1:通訊埠，
COM4： USB-SERIAL CH340
3.修改部分bug。
完整的工程已經上傳到我的csdn資源，需要的可以下載！
下載
1.基於vs2010，c#串列埠。
2.支援熱插拔。
3.支援儲存接收檔案txt格式，可與微控制器串列埠連線傳送資料。
4.視窗狀態列顯示。
5.登陸介面
6.顯示漢字

using System;
using System.Collections.Generic;
using System.ComponentModel;
using
 
 System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.IO;
using System.IO.Ports;
using System.Text.RegularExpressions;
using System.Threading;
namespace TEST
{
    public partial class Serial : Form
    {
        public Serial()
        {
            InitializeComponent();
        }

        private
 
 SerialPort comm = new SerialPort();
        private StringBuilder builder = new StringBuilder();
        private long received_count = 0;//接收計數
        private long send_count = 0;//傳送計數
        private string resultFile;
        private void Serial_Load(object sender, EventArgs e)
        {
            //初始化下拉串列埠名稱列表框
 

            string[] ports = SerialPort.GetPortNames();
            Array.Sort(ports);//排序
            comboPortName.Items.AddRange(ports);
            comboPortName.SelectedIndex = comboPortName.Items.Count > 0 ? 0 : -1;
            comboBaudrate.SelectedIndex = comboBaudrate.Items.IndexOf("9600");
            comboBoxstopb.SelectedIndex = comboBoxstopb.Items.IndexOf("1");
            comboBoxdateb.SelectedIndex = comboBoxdateb.Items.IndexOf("8");
            comboBoxjiou.SelectedIndex = comboBoxjiou.Items.IndexOf("無");
           // comm.NewLine = "/r/n";
          //  comm.RtsEnable = true;
            comm.DataReceived += comm_DataReceived;
            txSend.Text = "01 02 03 04 05 06 07 08";
            buttonSend.Enabled = false;
            toolStripStatusLabel5.Text = "      " + DateTime.Now.ToString();
        }

        private void Serial_FormClosing(object sender, FormClosingEventArgs e)
        {
            Application.Exit();
        }

        private void buttonopen_Click(object sender, EventArgs e)
        {
            //根據當前串列埠物件，來判斷操作
            if (comm.IsOpen)
            {
                //開啟時點選，則關閉串列埠
                comm.Close();
            }
            else
            {
                if (comboPortName.Text =="")
                {

                    MessageBox.Show("請插入串列埠裝置！");
                    return;

                }
                //關閉時點選，則設定好埠，波特率後開啟
                comm.PortName = comboPortName.Text;
                comm.BaudRate = int.Parse(comboBaudrate.Text);
                try
                {
                    comm.Open();

                }
                catch (Exception ex)
                {
                    //捕獲到異常資訊，建立一個新的comm物件，之前的不能用了。
                    // comm = new SerialPort();
                    //現實異常資訊給客戶。
                    MessageBox.Show(ex.Message);
                }
            }
            //設定按鈕的狀態
            buttonopen.Text = comm.IsOpen ? "關閉串列埠" : "開啟串列埠";
            buttonSend.Enabled = comm.IsOpen ? true:false;
            labelopenflag.ForeColor = comm.IsOpen ? Color.Red : Color.Black;
        }

        void comm_DataReceived(object sender, EventArgs e)
        {
            int n = comm.BytesToRead;//獲取快取區位元組數
            byte[] buf = new byte[n];//儲存串列埠資料用
            received_count += n;//接收計數
            comm.Read(buf, 0, n);//讀取緩衝資料
            builder.Clear();//清除字串構造器的內容

            //因為要訪問ui資源，所以需要使用invoke方式同步ui。
            this.Invoke((EventHandler)(delegate
            {
                //判斷是否是顯示為16禁止
                if (checkBoxHexView.Checked)
                {
                    //依次的拼接出16進位制字串
                    foreach (byte b in buf)
                    {
                        builder.Append(b.ToString("X2") + " ");
                    }
                }
                else
                {
                    //直接按ASCII規則轉換成字串
                     builder.Append(Encoding.Default.GetString(buf));
                }
                //追加的形式新增到文字框末端，並滾動到最後。
                this.txGet.AppendText(builder.ToString());
                //修改接收計數
                toolStripStatusLabel4.Text = "Recv:" + received_count.ToString();
            }));
        }
        private void buttonSend_Click(object sender, EventArgs e)
        {
            bool lineflag=false;
            //定義一個變數，記錄傳送了幾個位元組
            int n = 0;

            if (checkBoxNewlineSend.Checked)
            {
                lineflag = true;
            }
            //16進位制傳送
            if (checkBoxHexSend.Checked)
            {
                //正則得到有效的十六進位制數(?i)對大小寫不敏感，[/da-f]，{2}連續出現2次
               // MatchCollection mc = Regex.Matches(txSend.Text, @"(?i)[/da-f]{2}");
                MatchCollection mc = Regex.Matches(txSend.Text, @"(?i)[\da-f]{2}");
                List<byte> buf = new List<byte>();//填充到這個臨時列表中
                //依次新增到列表中
                foreach (Match m in mc)
                {
                    buf.Add(byte.Parse(m.Value, System.Globalization.NumberStyles.HexNumber));
                }
                //轉換列表為陣列後傳送
                comm.Write(buf.ToArray(), 0, buf.Count);
                if (lineflag == true)
                { //記錄傳送的位元組數
                    comm.WriteLine("\r\n");
                    n = buf.Count+2;
                }
                else
                    n = buf.Count;
            }
            else//ascii編碼直接傳送
            {

                    if (lineflag == true)
                    {
                        comm.Write(txSend.Text+"\r\n");
                        n = txSend.Text.Length + 2;
                    }
                    else//不包含換行符
                    {
                        comm.Write(txSend.Text);
                        n = txSend.Text.Length;
                    }
            }
            send_count += n;//累加發送位元組數
            toolStripStatusLabel3.Text = "Send:" + send_count.ToString();

        }

        private void buttonReset_Click(object sender, EventArgs e)
        {
            txSend.Clear();
            send_count  = 0;
            toolStripStatusLabel3.Text = "Send:0";
        }

        private void btncleanrec_Click(object sender, EventArgs e)
        {
            txGet.Clear();
            received_count = 0;
            toolStripStatusLabel4.Text = "Recv:0";
        }

        private void checkBox1_CheckedChanged(object sender, EventArgs e)
        {
            if (checkBox1.Checked)
            {

                txGet.BackColor = Color.Black;
                txGet.ForeColor = Color.GreenYellow;

            }
            else
            {
                txGet.BackColor = Color.White;
                txGet.ForeColor = Color.Black;
            }
        }

        //熱插拔
        protected override void DefWndProc(ref Message m)
        {
            if (m.Msg == 0x0219)
            {

                if (comm.IsOpen==false)
                {
                    bool flag = true;
                    string[] portnames = SerialPort.GetPortNames();
                    for (int i = 0; i < portnames.Length; i++)
                    {
                        if (comm.PortName == portnames[i])
                            flag = false;//不是本串列埠被拔                    
                    }
                    if (flag == true)//所有存在的串列埠中找不到已經開啟的串列埠                     
                    {
                        comboPortName.Text="";
                        //comm.Close();
                        buttonopen.Text = comm.IsOpen ? "關閉串列埠" : "開啟串列埠";
                        buttonSend.Enabled = comm.IsOpen ? true : false;
                        labelopenflag.ForeColor = comm.IsOpen ? Color.Red : Color.Black;
                    }

                }
            }
            base.DefWndProc(ref m);
        }

        private void comboPortName_Click(object sender, EventArgs e)
        {
            comboPortName.Items.Clear();
            string[] ports1 = SerialPort.GetPortNames();
            Array.Sort(ports1);//排序
            comboPortName.Items.AddRange(ports1);
            comboPortName.SelectedIndex = comboPortName.Items.Count > 0 ? 0 : -1;
        }

        private void timer1_Tick(object sender, EventArgs e)
        {
            toolStripStatusLabel5.Text="      "+DateTime.Now.ToString();
        }

        private void toolStripStatusLabel2_Click(object sender, EventArgs e)
        {
            System.Diagnostics.Process.Start("http://blog.csdn.net/xingkong886");  
        }

        private void btnsave_Click(object sender, EventArgs e)
        {
            /*
            if (txGet.Text == "")
            {
                MessageBox.Show("沒有資料儲存!","錯誤");
                return;
            }
             */
            SaveFileDialog SaveFile = new SaveFileDialog();
            // SaveFile.InitialDirectory = "E:\\1work\\FILE";//初始目錄
            SaveFile.Filter = "All files(*.*)|*.*|txt files(*.txt)|*.txt";//文字篩選
            SaveFile.FilterIndex = 3;//文字篩選器索引，選擇第一項就是1
            SaveFile.RestoreDirectory = true;

            if (SaveFile.ShowDialog() == DialogResult.OK)
            {
                resultFile = SaveFile.FileName;
                StreamWriter sw = File.CreateText(resultFile);
                sw.WriteLine(DateTime.Now.ToString());
                sw.Write(txGet.Text);
                sw.Close();
            }
        }

    }
}