Code:

//create a SerialPort object
SerialPort sp = new SerialPort ();

默认情况下，DataBits 值是8，StopBits 是1，通信端口是COM1。这些都可以在下面的属性中重新设置

：

BaudRate：串口的波特率
StopBits：每个字节的停止位数量
ReadTimeout：当读操作没有完成时的停止时间。单位，毫秒

还有不少其它公共属性，自己查阅MSDN。

串口的硬件知识

在数据传输的时候，每个字节的数据通过单个的电缆线传输。包包括开始位，数据，结束为。一旦

开始位传出，后面就会传数据，可能是5，6，7或8位，就看你的设定了。发送和接收必须设定同样

的波特率和数据位数。

无猫模式

没有Modem模式的电缆只是简单地交叉传送和接收线。同样DTR & DSR, 和 RTS & CTS也需要交叉。

RS232针图

Code:

#region Using directives

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Windows.Forms;
using System.IO.Ports;

#endregion

namespace Serialexpample
{
    partial class Form1 : Form
    {
        //create instance of property page
        //property page is used to set values for stop bits and
        //baud rate

        PropertyPage pp = new PropertyPage();

        //create an Serial Port object
        SerialPort sp = new SerialPort();

        public Form1()
        {
            InitializeComponent();
        }
            
        private void propertyButton_Click(object sender, EventArgs e)
        {
            //show property dialog
            pp.ShowDialog();

            propertyButton.Hide();
        }

        private void sendButton_Click(object sender, EventArgs e)
        {
            try
            {
                //write line to serial port
                sp.WriteLine(textBox.Text);
                //clear the text box
                textBox.Text = "";
            }
            catch (System.Exception ex)
            {
                baudRatelLabel.Text = ex.Message;
            }

        }

        private void ReadButton_Click(object sender, EventArgs e)
        {
            try
            {
                //clear the text box
                textBox.Text = "";
                //read serial port and displayed the data in text box
                textBox.Text = sp.ReadLine();
            }
            catch(System.Exception ex)
            {
                baudRatelLabel.Text = ex.Message;
            }
        }

        private void Form1_Load(object sender, EventArgs e)
        {

        }

        private void Form1_FormClosing(object sender, FormClosingEventArgs e)
        {
            MessageBox.Show("Do u want to Close the App");
            sp.Close();
        }

        private void startCommButton_Click(object sender, EventArgs e)
        {
            startCommButton.Hide();
            sendButton.Show();
            readButton.Show();
            textBox.Show();
        }

        //when we want to save the status(value)
        private void saveStatusButton_Click_1(object sender, EventArgs e)
        {
            //display values
            //if no property is set the default values
            if (pp.bRate == "" && pp.sBits == "")
            {
                dataBitLabel.Text = "BaudRate = " + sp.BaudRate.ToString();
                readTimeOutLabel.Text = "StopBits = " + sp.StopBits.ToString();
            }
            else
            {
                dataBitLabel.Text = "BaudRate = " + pp.bRate;
                readTimeOutLabel.Text = "StopBits = " + pp.sBits;
            }

            parityLabel.Text = "DataBits = " + sp.DataBits.ToString();
            stopBitLabel.Text = "Parity = " + sp.Parity.ToString();
            readTimeOutLabel.Text = "ReadTimeout = " +
                      sp.ReadTimeout.ToString();

            if (propertyButton.Visible == true)
                propertyButton.Hide();
            saveStatusButton.Hide();
            startCommButton.Show();

            try
            {
                //open serial port
                sp.Open();
                //set read time out to 500 ms
                sp.ReadTimeout = 500;
            }
            catch (System.Exception ex)
            {
                baudRatelLabel.Text = ex.Message;
            }
        }
    }
}

属性设置对话框代码：

Code:

#region Using directives

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;

#endregion

namespace Serialexpample
{
    partial class PropertyPage : Form
    {
        //variables for storing values of baud rate and stop bits
        private string baudR="";
        private string stopB="";

        //property for setting and getting baud rate and stop bits
        public string bRate
        {
            get
            {
                return baudR;
            }
            set
            {
                baudR = value;
            }
        }

        public string sBits
        {
            get
            {
                return stopB;
            }
            set
            {
                stopB = value;
            }
        }

        public PropertyPage()
        {
            InitializeComponent();
        }

        private void cancelButton_Click(object sender, EventArgs e)
        {
            this.bRate = "";
            this.sBits = "";
            //close form
            this.Close();
        }

        private void okButton_Click_1(object sender, EventArgs e)
        {
            //here we set the value for stop bits and baud rate.
            this.bRate = BaudRateComboBox.Text;
            this.sBits = stopBitComboBox.Text;
            //
            this.Close();

        }
    }
}