using System;
using System.IO.Ports;


class SerialPortHelper
{
    private long _receiveByteCount = 0, _sendByteOfCount = 0;


    public long ReceiveByteCount { get { return _receiveByteCount; } set { _receiveByteCount = value; } }
    public long SendByteOfCount { get { return _sendByteOfCount; } set { _sendByteOfCount = value; } }


    SerialPort _serialPort = new SerialPort();


    private DataReceived _received = null;


    public delegate void DataReceived(byte[] data);


    public bool IsOpen { get { return _serialPort.IsOpen; } }


    public static string[] SerialPortNames
    {
        get
        {
            string[] serialports = SerialPort.GetPortNames();
            Array.Sort(serialports, new Comparison<string>(
                delegate(string x, string y)
                {
                    if (x.Length > 3 && y.Length > 3)
                    {
                        string index1 = x.Substring(3);
                        string index2 = y.Substring(3);
                        try
                        {
                            int n1 = Convert.ToInt32(index1);
                            int n2 = Convert.ToInt32(index2);
                            return n1 - n2;
                        }
                        catch
                        {
                        }
                    }
                    return 0;
                }));
            return serialports;
        }
    }


    public SerialPortHelper(DataReceived received)
    {
        _received = received;
        _serialPort.NewLine = "\r\n";
        _serialPort.DataReceived += delegate
        {
            System.Threading.Thread.Sleep(50);
            int ReadLength = _serialPort.BytesToRead;
            if (ReadLength > 0)
            {
                _receiveByteCount += ReadLength;
                byte[] ReadBuffer = new byte[ReadLength];
                _serialPort.Read(ReadBuffer, 0, ReadLength);
                if(_received!=null)
                {
                    _received(ReadBuffer);
                }
            }
        };
    }


    public void Open(string PortName)
    {
        _serialPort.PortName = PortName;
        _serialPort.StopBits = StopBits.One;
        _serialPort.Parity = Parity.None;
        _serialPort.DataBits = 8;
        _serialPort.BaudRate = 19200;
        _serialPort.Open();
    }


    public void Close()
    {
        _serialPort.Close();
    }


    public void WriteLine(string text)
    {
        if (_serialPort.IsOpen)
        {
            _sendByteOfCount += text.Length;
            _serialPort.WriteLine(text);
        }
    }


    public void Write(byte[] buffer)
    {
        if (_serialPort.IsOpen)
        {
            _serialPort.Write(buffer, 0, buffer.Length);
            _sendByteOfCount += buffer.Length;
        }
    }
}

调用：

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;


namespace SerialnumPort1
{
    public partial class Form1 : Form
    {
        string _tempfile = AppDomain.CurrentDomain.BaseDirectory + "temp.data";
        SerialPortHelper _helper = null;
        public Form1()
        {
            InitializeComponent();
            _helper = new SerialPortHelper(delegate(byte[] data)
                                                                    {
                                                                        this.Invoke(
                                                                         (EventHandler)delegate
                                                                         {
                                                                             if (checkBox2.Checked)
                                                                             {
                                                                                 using (System.IO.FileStream fs = new System.IO.FileStream(_tempfile, System.IO.FileMode.Append))
                                                                                 {
                                                                                     fs.Write(data, 0, data.Length);
                                                                                 }
                                                                             }

                                                                             StringBuilder readStr = new StringBuilder();
                                                                             foreach (byte b in data)
                                                                             {
                                                                                 string temp = string.Format("{0:X2} ", b);
                                                                                 readStr.Append(temp);
                                                                             }
                                                                             readStr.Append("已接收\r\n");

                                                                             toolStripStatusLabel1.Text = "已接收字节数：" + _helper.ReceiveByteCount;
                                                                             richTextBox1.AppendText(readStr.ToString());
                                                                             richTextBox1.ScrollToCaret();
                                                                         }
                                                                        );
                                                                    });
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            string[] serialnums = SerialPortHelper.SerialPortNames;
            comboBox1.Items.AddRange(serialnums);
        }

        private void button2_Click(object sender, EventArgs e)
        {
            if ("打开" == button2.Text)
            {
                try
                {
                    _helper.Open(comboBox1.Text);
                    button2.Text = "关闭";
                }
                catch (Exception ex)
                {
                    MessageBox.Show(ex.Message + "\r\n" + ex.StackTrace);
                }
            }
            else
            {
                button2.Text = "打开";
                _helper.Close();
            }
        }

        private void button1_Click(object sender, EventArgs e)
        {
            if (_helper.IsOpen)
            {
                if (!checkBox1.Checked)
                {
                    _helper.WriteLine(textBox1.Text);
                }
                else
                {
                    string sendtext = textBox1.Text.TrimEnd(‘ ‘);
                    string[] sps = sendtext.Split(‘ ‘);
                    byte[] sendata = http://www.mamicode.com/new byte[sps.Length];" 已发送\r\n");
                richTextBox1.ScrollToCaret();
                toolStripStatusLabel2.Text = "已发送字节数：" + _helper.SendByteOfCount;
            }
        }

        private void checkBox2_CheckedChanged(object sender, EventArgs e)
        {
            if (checkBox2.Checked)
            {
                System.IO.File.Delete(_tempfile);
                using (System.IO.FileStream fs = System.IO.File.Create(_tempfile))
                {
                }
            }
        }

    }
}