C#实现串口监听

Visual Stdio 2005中,对于串口操作Framework提供了一个很好的类接口-SerialPort,在这当中,串口数据的读取与写入有较大的不同。由于串口不知道数据何时到达，因此有两种方法可以实现串口数据的读取。

       1.用线程实时读串口

       2.用事件触发方式实现。

        但由于线程实时读串口的效率不是十分高效，因此比较好的方法是事件触发的方式。在SerialPort类中有DataReceived事件，当串口的读缓存有数据到达时则触发DataReceived事件，其中SerialPort.ReceivedBytesThreshold属性决定了当串口读缓存中数据多少个时才触发DataReceived事件，默认为1。

       此外，SerialPort.DataReceived事件运行比较特殊，其运行在辅线程，不能与主线程中的显示数据控件直接进行数据传输，必须用间接的方式实现。

一.创建WIndow项目,设计界面

二,编写实现代码

 

1. using System;
2. using System.Collections.Generic;
3. using System.ComponentModel;
4. using System.Data;
5. using System.Drawing;
6. using System.Text;
7. using System.Windows.Forms;
8. using System.IO.Ports;
9. using System.Threading;
10. using Microsoft.Win32;
12. namespace ComMonitor
13. {
14.     public partial class Form1 : Form
15.      {
16.         public Form1()
17.          {
18.              InitializeComponent();
19.          }
21.         private SerialPort Sp = new SerialPort();
22.         public delegate void HandleInterfaceUpdataDelegate(string text); //委托，此为重点
23.         private HandleInterfaceUpdataDelegate interfaceUpdataHandle;
25.         private bool qiii = false;
28.         private void btENT_Click(object sender, EventArgs e)
29.          {
30.             if ((cmID.Text.Trim() != "") && (cmRate.Text != ""))
31.              {
32.                  interfaceUpdataHandle = new HandleInterfaceUpdataDelegate(UpdateTextBox);//实例化委托对象
33.                  Sp.PortName = cmID.Text.Trim();
34.                  Sp.BaudRate = Convert.ToInt32(cmRate.Text.Trim());
35.                  Sp.Parity = Parity.None;
36.                  Sp.StopBits = StopBits.One;
37.                  Sp.DataReceived += new SerialDataReceivedEventHandler(Sp_DataReceived);
38.                  Sp.ReceivedBytesThreshold = 1;
39.                 try
40.                  {
41.                      Sp.Open();
43.                      ATCommand3("AT+CLIP=1\r", "OK");
46.                      btPause.Enabled = true;
47.                      btENT.Enabled = false;
48.                  }
49.                 catch
50.                  {
51.                      MessageBox.Show("端口" + cmID.Text.Trim() + "打开失败！");
52.                  }
53.              }
54.             else
55.              {
56.                  MessageBox.Show("请输入正确的端口号和波特率！");
57.                  cmID.Focus();
58.              }
60.          }
62.         private void btPause_Click(object sender, EventArgs e)
63.          {
64.              Sp.Close();
65.              btENT.Enabled = true;
66.              btPause.Enabled = false;
68.          }
70.         private void Form1_FormClosing(object sender, FormClosingEventArgs e)
71.          {
72.              Sp.Close();
74.          }
76.         private void Form1_Load(object sender, EventArgs e)
77.          {
78.              GetComList();
79.              btPause.Enabled = false;
81.          }
83.         public void Sp_DataReceived(object sender,System.IO.Ports.SerialDataReceivedEventArgs e)
84.          {
85.             string strTemp = "";
86.             double iSecond = 0.5;
88.              DateTime dtOld = System.DateTime.Now;
89.              DateTime dtNow = System.DateTime.Now;
90.              TimeSpan dtInter;
91.              dtInter = dtNow - dtOld;
93.             int i = Sp.BytesToRead;
94.             if (i > 0)
95.              {
96.                 try
97.                  {
98.                      strTemp = Sp.ReadExisting();
99.                  }
100.                 catch
101.                  { }
102.                 if (strTemp.ToLower().IndexOf("\r") < 0)
103.                  {
104.                      i = 0;
105.                  }
106.                 else
107.                  {
108.                     this.Invoke(interfaceUpdataHandle, strTemp);
109.                  }
110.              }
111.             while (dtInter.TotalSeconds < iSecond && i <= 0)
112.              {
113.                  dtNow = System.DateTime.Now;
114.                  dtInter = dtNow - dtOld;
115.                  i = Sp.BytesToRead;
116.                 if (i > 0)
117.                  {
118.                     try
119.                      {
120.                          strTemp += Sp.ReadExisting();
121.                      }
122.                     catch
123.                      { }
124.                     if (strTemp.ToLower().IndexOf("\r") < 0)
125.                      {
126.                          i = 0;
127.                      }
128.                     else
129.                      {
130.                         this.Invoke(interfaceUpdataHandle, strTemp);
131.                      }
132.                  }
133.              }
134.             // do null
136.          }
138.         private void UpdateTextBox(string text)
139.          {
140.              tbData.Text = text;
141.          }
143.         /// <summary>
144.         /// 执行AT指令并返回 成功失败
145.         /// </summary>
146.         /// <param name="ATCmd">AT指令</param>
147.         /// <param name="StCmd">AT指令标准结束标识</param>
148.         /// <returns></returns>
149.         private void ATCommand3(string ATCmd, string StCmd)
150.          {
151.             string response = "";
152.              response = ATCommand(ATCmd, StCmd);
155.          }
157.         /// <summary>
158.         /// 执行AT指令并返回结果字符
159.         /// </summary>
160.         /// <param name="ATCmd">AT指令</param>
161.         /// <param name="StCmd">AT指令标准结束标识</param>
162.         /// <returns></returns>
163.         private string ATCommand(string ATCmd, string StCmd)
164.          {
165.             string response = "";
166.             int i;
167.             if (!ATCmd.EndsWith("\x01a"))
168.              {
169.                 if (!(ATCmd.EndsWith("\r") || ATCmd.EndsWith("\r\n")))
170.                  {
171.                      ATCmd = ATCmd + "\r";
172.                  }
173.              }
174.              Sp.WriteLine(ATCmd);
176.             //第一次读响应数据
177.             if (Sp.BytesToRead > 0)
178.              {
179.                  response = Sp.ReadExisting();
181.                 //去除前端多可能多读取的字符
182.                 if (response.IndexOf(ATCmd) > 0)
183.                  {
184.                      response = response.Substring(response.IndexOf(ATCmd));
185.                  }
186.                 else
187.                  {
189.                  }
191.                 if (response == "" || response.IndexOf(StCmd) < 0)
192.                  {
193.                     if (response != "")
194.                      {
195.                         if (response.Trim() == "ERROR")
196.                          {
197.                             //throw vError = new UnknowException("Unknown exception in sending command:" + ATCmd);
198.                          }
199.                         if (response.IndexOf("+CMS ERROR") >= 0)
200.                          {
201.                             string[] cols = new string[100];
202.                              cols = response.Split(';');
203.                             if (cols.Length > 1)
204.                              {
205.                                 string errorCode = cols[1];
206.                              }
207.                          }
208.                      }
209.                  }
210.              }
212.             //读第一次没有读完的响应数据，直到读到特征数据或超时
213.             for (i = 0; i < 3; i++)
214.              {
215.                  Thread.Sleep(1000);
216.                  response = response + Sp.ReadExisting();
217.                 if (response.IndexOf(StCmd) >= 0)
218.                  {
219.                     break;
220.                  }
221.              }
223.             return response;
226.          }
228.         /// <summary>
229.         /// 从注册表获取系统串口列表
230.         /// </summary>
231.         private void GetComList()
232.          {
233.              RegistryKey keyCom = Registry.LocalMachine.OpenSubKey("Hardware\\DeviceMap\\SerialComm");
234.             if (keyCom != null)
235.              {
236.                 string[] sSubKeys = keyCom.GetValueNames();
237.                 this.cmID.Items.Clear();
238.                 foreach (string sName in sSubKeys)
239.                  {
240.                     string sValue = (string)keyCom.GetValue(sName);
241.                     this.cmID.Items.Add(sValue);
242.                  }
243.              }
244.          }
246.         private void cmID_DropDown(object sender, EventArgs e)
247.          {
248.              GetComList();
249.          }
251.      }
252. }