需要说明的是：这是程序的一部分，因此有一些与具体应用无关的部分。
关键是原理，而不是程序本身.后面有些使用介绍，帮助理解这长的程序。

头文件(.H)

#include "StdAfx.h"

#define GWL_PGPSINFO 0
#define GPSEXTRABYTES sizeof( LONG )

#define MAXPORTS 4

#define CN_SEND WM_USER+100

#define RXQUEUE 4096
#define TXQUEUE 4096


// cursor states

#define CS_HIDE 0x00
#define CS_SHOW 0x01

// Flow control flags

#define FC_DTRDSR 0x01
#define FC_RTSCTS 0x02
#define FC_XONXOFF 0x04

// ascii definitions

#define ASCII_BEL 0x07
#define ASCII_BS 0x08
#define ASCII_LF 0x0A
#define ASCII_CR 0x0D
#define ASCII_XON 0x11
#define ASCII_XOFF 0x13

// data structures


typedef struct tagGPSINFO
{
HANDLE idComDev;
BYTE bPort;
BOOL fConnected;
BYTE bByteSize,bParity,bStopBits;
DWORD dwBaudRate;

HANDLE hPostEvent,hWatchThread,hWatchEvent;
HWND hTermWnd;
DWORD dwThreadID;
OVERLAPPED osWrite,osRead;
} GPSINFO, *PGPSINFO ;

#define COMDEV( x ) (x -> idComDev)
#define PORT( x ) (x -> bPort)
#define CONNECTED( x ) (x -> fConnected)
#define BYTESIZE( x ) (x -> bByteSize)
#define PARITY( x ) (x -> bParity)
#define STOPBITS( x ) (x -> bStopBits)
#define BAUDRATE( x ) (x -> dwBaudRate)


#define POSTEVENT( x ) (x -> hPostEvent)
#define HTHREAD( x ) (x -> hWatchThread)
#define THREADID( x ) (x -> dwThreadID)
#define WRITE_OS( x ) (x -> osWrite)
#define READ_OS( x ) (x -> osRead)

// function prototypes (private)

LRESULT NEAR CreateGPSInfo(HWND,BYTE nPort=1);
BOOL NEAR DestroyGPSInfo();

int NEAR ReadCommBlock(LPSTR,int);
BOOL NEAR WriteCommBlock(LPSTR,DWORD);
BOOL NEAR OpenConnection();
BOOL NEAR SetupConnection();
BOOL NEAR CloseConnection();

// function prototypes (public)

DWORD FAR PASCAL CommWatchProc(LPSTR);



具体实现请看下文(为了这文章，我都段线2次了)

CPP实现部分：

#include "StdAfx.h"
#include "Com.h"

HWND hGPSWnd=NULL;
PGPSINFO npGPSInfo=NULL;

LRESULT NEAR CreateGPSInfo(HWND hWnd,BYTE nPort)
{
if (NULL==(npGPSInfo=(PGPSINFO)LocalAlloc(LPTR,sizeof(GPSINFO))))
return ((LRESULT)-1) ;

hGPSWnd=hWnd;

COMDEV(npGPSInfo)=0;
CONNECTED(npGPSInfo)=FALSE;
PORT(npGPSInfo)=nPort;
BAUDRATE(npGPSInfo)=CBR_9600;
BYTESIZE(npGPSInfo)=8;
PARITY(npGPSInfo)=NOPARITY;
STOPBITS(npGPSInfo)=ONESTOPBIT;

WRITE_OS(npGPSInfo).Offset=0;
WRITE_OS(npGPSInfo).OffsetHigh=0;
READ_OS(npGPSInfo).Offset=0;
READ_OS(npGPSInfo).OffsetHigh=0;

// create I/O event used for overlapped reads / writes

READ_OS(npGPSInfo).hEvent=CreateEvent(NULL,TRUE,FALSE,NULL);
if (READ_OS(npGPSInfo).hEvent==NULL)
{ LocalFree( npGPSInfo ) ;
return ( -1 ) ;
}
WRITE_OS(npGPSInfo).hEvent=CreateEvent(NULL,TRUE,FALSE,NULL);
if (NULL==WRITE_OS(npGPSInfo).hEvent)
{ CloseHandle(READ_OS(npGPSInfo).hEvent);
LocalFree(npGPSInfo) ;
return (-1) ;
}


return ( (LRESULT) TRUE ) ;
}

BOOL NEAR DestroyGPSInfo()
{
if (!npGPSInfo) return (FALSE);

if (CONNECTED(npGPSInfo)) CloseConnection();

CloseHandle(READ_OS(npGPSInfo).hEvent);
CloseHandle(WRITE_OS(npGPSInfo).hEvent);
CloseHandle(POSTEVENT(npGPSInfo));

LocalFree(npGPSInfo);
return (TRUE);
}

BOOL NEAR OpenConnection()
{
char szPort[15];
BOOL fRetVal;
HCURSOR hOldCursor,hWaitCursor;

HANDLE hCommWatchThread;
DWORD dwThreadID;
COMMTIMEOUTS CommTimeOuts;

if (!npGPSInfo) return (FALSE);

hWaitCursor=LoadCursor(NULL,IDC_WAIT) ;
hOldCursor=SetCursor(hWaitCursor) ;

wsprintf(szPort,"COM%d",PORT(npGPSInfo));

if
((COMDEV(npGPSInfo)=CreateFile(szPort,GENERIC_READ|GENERIC_WRITE,

0,NULL,OPEN_EXISTING,FILE_ATTRIBUTE_NORMAL|FILE_FLAG_OVERLAPPED,
NULL))==(HANDLE)-1)
return ( FALSE ) ;
else
{ SetCommMask(COMDEV(npGPSInfo),EV_RXCHAR);
SetupComm(COMDEV(npGPSInfo),4096,4096);


PurgeComm(COMDEV(npGPSInfo),PURGE_TXABORT|PURGE_RXABORT|PURGE_TXCLEAR|

PURGE_R
XCLEAR);
CommTimeOuts.ReadIntervalTimeout=0xFFFFFFFF;
CommTimeOuts.ReadTotalTimeoutMultiplier=0;
CommTimeOuts.ReadTotalTimeoutConstant=1000;
CommTimeOuts.WriteTotalTimeoutMultiplier=0;
CommTimeOuts.WriteTotalTimeoutConstant=1000;
SetCommTimeouts(COMDEV(npGPSInfo),&CommTimeOuts);
}

fRetVal=SetupConnection();

if (fRetVal)
{ CONNECTED(npGPSInfo)=TRUE;
if
(NULL==(hCommWatchThread=CreateThread((LPSECURITY_ATTRIBUTES)NULL,

0,(LPTHREAD_START_ROUTINE)CommWatchProc,
(LPVOID)NULL,0,&dwThreadID)))
{ CONNECTED(npGPSInfo)=FALSE;
CloseHandle(COMDEV(npGPSInfo));
fRetVal=FALSE;
}
else
{ THREADID(npGPSInfo)=dwThreadID;
HTHREAD(npGPSInfo)=hCommWatchThread;
EscapeCommFunction(COMDEV(npGPSInfo),SETDTR);
}
}
else
{ CONNECTED(npGPSInfo)=FALSE;
CloseHandle(COMDEV(npGPSInfo));
}

SetCursor(hOldCursor);
return (fRetVal);
}

BOOL NEAR SetupConnection()
{ BOOL fRetVal;
DCB dcb;


if (!npGPSInfo) return(FALSE);

dcb.DCBlength=sizeof(DCB);

GetCommState(COMDEV(npGPSInfo),&dcb);

dcb.BaudRate=BAUDRATE(npGPSInfo);
dcb.ByteSize=BYTESIZE(npGPSInfo);
dcb.Parity=PARITY(npGPSInfo);
dcb.StopBits=STOPBITS(npGPSInfo);

dcb.fOutxDsrFlow=FALSE;
dcb.fDtrControl=DTR_CONTROL_ENABLE;

dcb.fOutxCtsFlow=FALSE;
dcb.fRtsControl=RTS_CONTROL_ENABLE;
dcb.fInX=dcb.fOutX=FALSE;
dcb.fBinary=TRUE;
dcb.fParity=TRUE;

fRetVal=SetCommState(COMDEV(npGPSInfo),&dcb);
return (fRetVal);
}

BOOL NEAR CloseConnection()
{
if (!npGPSInfo) return(FALSE);

CONNECTED(npGPSInfo)=FALSE;

SetCommMask(COMDEV(npGPSInfo),0);
while(THREADID(npGPSInfo)!=0);

EscapeCommFunction(COMDEV(npGPSInfo),CLRDTR);
PurgeComm(COMDEV(npGPSInfo),PURGE_TXABORT|PURGE_RXABORT|
PURGE_TXCLEAR|PURGE_RXCLEAR);
CloseHandle(COMDEV(npGPSInfo));

return (TRUE);
}

int NEAR ReadCommBlock(LPSTR lpszBlock,int nMaxLength)
{
BOOL fReadStat ;
COMSTAT ComStat ;
DWORD dwErrorFlags;
DWORD dwLength;
DWORD dwError;

if (!npGPSInfo) return(FALSE);

ClearCommError(COMDEV(npGPSInfo),&dwErrorFlags,&ComStat);
dwLength=min((DWORD)nMaxLength,ComStat.cbInQue);

if (dwLength>0)
{ fReadStat=ReadFile(COMDEV(npGPSInfo),lpszBlock,

dwLength,&dwLength,&READ_OS(npGPSInfo));
if (!fReadStat)
{ if (GetLastError()==ERROR_IO_PENDING)
{ OutputDebugString("\n\rIO Pending");

while(!GetOverlappedResult(COMDEV(npGPSInfo),&READ_OS(npGPSInfo),&dwLe

ngth,TR
UE))
UE))
{ dwError=GetLastError();
if(dwError == ERROR_IO_INCOMPLETE)
continue;
}

}
else
{ dwLength=0;

ClearCommError(COMDEV(npGPSInfo),&dwErrorFlags,&ComStat);
}
}
}
return ( dwLength ) ;
}

BOOL NEAR WriteCommBlock(LPSTR lpByte,DWORD dwBytesToWrite)
{ BOOL fWriteStat;
DWORD dwBytesWritten;
DWORD dwErrorFlags;
DWORD dwError;
COMSTAT ComStat;

if (!npGPSInfo) return(FALSE);

fWriteStat=WriteFile(COMDEV(npGPSInfo),lpByte,dwBytesToWrite,
&dwBytesWritten,&WRITE_OS(npGPSInfo));

if (!fWriteStat)
{ if(GetLastError()==ERROR_IO_PENDING)
{ while(!GetOverlappedResult(COMDEV(npGPSInfo),
&WRITE_OS(npGPSInfo),&dwBytesWritten,TRUE))
{ dwError=GetLastError();
if(dwError == ERROR_IO_INCOMPLETE)
continue;
else
{
ClearCommError(COMDEV(npGPSInfo),&dwErrorFlags,&ComStat);
break;
}
}
}
else
{
{
ClearCommError(COMDEV(npGPSInfo),&dwErrorFlags,&ComStat);
return ( FALSE );
}
}
return ( TRUE ) ;

}

DWORD FAR PASCAL CommWatchProc(LPSTR)
{ DWORD dwEvtMask;
OVERLAPPED os;
int nLength;
BYTE abIn[1024];

memset(&os,0,sizeof(OVERLAPPED));

// create I/O event used for overlapped read

os.hEvent=CreateEvent(NULL,TRUE,FALSE,NULL);
if (os.hEvent==NULL)
{ MessageBox(NULL,"Failed to create event for thread!","GPS
Error!",MB_ICONEXCLAMATION|MB_OK);
return ( FALSE ) ;
}

if (!SetCommMask(COMDEV(npGPSInfo),EV_RXCHAR)) return (FALSE);

while (CONNECTED( npGPSInfo))
{ dwEvtMask=0 ;
WaitCommEvent(COMDEV(npGPSInfo),&dwEvtMask,NULL);

if ((dwEvtMask&EV_RXCHAR)==EV_RXCHAR)
{ do
{ if
(nLength=ReadCommBlock((LPSTR)abIn,1024))
{
//WriteCommBlock((LPSTR)abIn,nLength );
*(abIn+nLength)=0;

::SendMessage(hGPSWnd,CN_SEND,nLength,(LONG)(LPSTR)abIn);
}
}
while ((nLength>0)&&(CONNECTED( npGPSInfo)));
}
}
}

CloseHandle(os.hEvent);
THREADID(npGPSInfo)=0;
HTHREAD(npGPSInfo)=NULL;
return(TRUE);
}


就这些了，希望能对问这些问题的朋友有所帮助!

一般使用的顺序是：
CreateGPSInfo(被通知的窗口句柄，串口端口号1或2);
OpenConnection();//建立联结它会调用SetupConnection
DestroyGPSInfo();//解除联结它会调用CloseConnection

可以用ReadCommBlock/WriteCommBlock来读/写串口
CommWatchProc是监视串口的线程，由OpenConnection建立


当串口有数据来的时侯，它会通知'被通知的窗口句柄'的窗口数据传到的消息(自

定义的)
SendMessage(hGPSWnd,CN_SEND,nLength,(LONG)(LPSTR)abIn);

好了，文章结束了！希望能帮助你！