C# 命名空间
private AxMSCommLib.AxMSComm MSCOMM;


用到哪个命名空间呀

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调用MSCOMM32.OCX控件可以实现串口通信
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先注册，后使用
http://www.cnblogs.com/zpjwys/archive/2009/02/05/1384626.html
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　　代码如下:
using ;
using .Text;
using .Drawing;
using .Collections;
using .ComponentModel;
using .Windows.Forms;
using .Data;
complc
{
/// <summary>
/// Form1 摘要介绍说明
/// </summary> [Page]
public comForm : .Windows.Forms.Form
{
private AxMSCommLib.AxMSComm axMSComm1;
private .Windows.Forms.TextBox textBox1;
private .Windows.Forms.TextBox textBox2;
private .Windows.Forms.Button button1;
private .Windows.Forms.Button button2;
private .Windows.Forms.Label label1;
private .Windows.Forms.Label label2;
/// <summary>
/// 必需设计器变量
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或者这里

http://download.csdn.net/source/1062532