串口的操作可以有两种操作方式：同步操作方式和重叠操作方式（又称为异步操作方式）。同步操作时，API函数会阻塞直到操作完成以后才能返回（在多线程方式中，虽然不会阻塞主线程，但是仍然会阻塞监听线程）；而重叠操作方式，API函数会立即返回，操作在后台进行，避免线程的阻塞。

个类的基类。

该MFC参考通常不描述通过继承的函数或操作符。若要寻求这些函数的信息，请参阅类层次结构图中该类的基类信息。

每个类的说明文档包括：该类的概括、类成员的种类、以及该成员函数、重载操作符或数据成员的基本用途。

-The MFC library reference covers the basic of Microsoft in the classes, global functions, global variables and macro content. Refer to the " class hierarchy diagram"　in order to facilitate the search for a class base class. The MFC is usually not described by reference to the succession of the function or operator. To find these functions, please refer to the class hierarchy diagram of the base class type of information. Documentation for each category include: the broad class, class member types, and the member functions, overloaded operators or data members of the basic use.