采用异步I/O,readfile()从串口读取数据不全?

Question

       COMMTIMEOUTS TimeOuts;
        memset(&TimeOuts,0,sizeof(TimeOuts));
        TimeOuts.ReadIntervalTimeout = MAXDWORD;
        TimeOuts.ReadTotalTimeoutConstant = 10;
        TimeOuts.ReadTotalTimeoutMultiplier = 10;
        TimeOuts.WriteTotalTimeoutConstant = 2000;
        TimeOuts.WriteTotalTimeoutMultiplier = 50;     ReadFile(hCom,pszRecv,1024,&ReadBytes,&ReadOver)
发现只读取了8个字节的数据（ReadBytes的值是8），本来要读取25个字节的数据。不知道哪里出了问题？

Answer 1

这是读线程DWORD WINAPI ReadCommThread(LPARAM lparam)///读线程
{
    extern charCount;
    extern HANDLE m_hCom;
    extern OpenCloseFlag;
    extern unsigned char pszRecv[1024];
    DWORD ReadBytes;
DWORD bResult;
DWORD dwErr;
OVERLAPPED ReadOver;
DWORD hMask;
DWORD CommEvent;
int i=0;
CRITICAL_SECTION section;
COMSTAT comstat;
DWORD Flag=0;
memset(&ReadOver,0x00,sizeof(ReadOver));
     ReadOver.Offset=0;
    ReadOver.OffsetHigh=0;
ReadOver.hEvent=CreateEvent(NULL,TRUE,FALSE,NULL);
PurgeComm(m_hCom,PURGE_TXABORT | PURGE_TXCLEAR | PURGE_RXABORT | PURGE_RXCLEAR);
InitializeCriticalSection(&section);
   
    for(;;)
{
bResult=WaitCommEvent(m_hCom,&hMask,&ReadOver);   
if(OpenCloseFlag==1)  //串口已被打开才做下一部
{ 
     if(!bResult)
     {
     switch(dwErr=GetLastError())
     {
     case ERROR_IO_PENDING:
                      
                   // MessageBox(NULL,"读取成功",0,MB_OK);
     Flag^=1;
     break;
     /* case 87:
                    
     break;*/
     default:
         SetDlgItemText((HWND)lparam,IDC_COMMSTATE,"WaitCommEvent Error");
     goto ErrorNext;
     }
     }else
     {
     bResult=ClearCommError(m_hCom,&dwErr,&comstat);
     if(comstat.cbInQue==0)
        continue;
     }
     WaitForSingleObject(ReadOver.hEvent,INFINITE);///等侍异步操作完成
     Flag=0;
           //ResetEvent(ReadOver.hEvent);////设置为不发信号状态
     GetCommMask(m_hCom,&hMask);
     if(hMask & EV_CTS)//CTS信号改变 
     {
     }
     if(hMask & EV_RXFLAG)//收到特殊字符 
     {
     }
     if(hMask & EV_BREAK)
     {
     }
     if(hMask & EV_ERR)//端口错误信号
     {
     }
     if(hMask & EV_RING)       //ring信号变化 
     {
     }
    
     if(hMask & EV_RXCHAR)///收到一个或多个字符
     {
        
                EnterCriticalSection(&section);
         bResult=ClearCommError(m_hCom,&dwErr,&comstat);
     if(!ReadFile(m_hCom,pszRecv,1024,&ReadBytes,&ReadOver))
     {
     switch(dwErr=GetLastError())
     {
     case ERROR_IO_PENDING:
     Flag^=1;
     break;
     default:
     goto ErrorNext;
     }
     } 
     if(Flag & 1)
     {
                   
     SetDlgItemText((HWND)lparam,IDC_COMMSTATE,"正在读取数据");
    
     WaitForSingleObject(ReadOver.hEvent,INFINITE);
     if(GetOverlappedResult(m_hCom,&ReadOver,&ReadBytes,TRUE))
     {
     SetDlgItemText((HWND)lparam,IDC_COMMSTATE,"读取数据完成");
     SetDlgItemText((HWND)lparam,IDC_SHOWINFO,pszRecv);
     }
     }
        LeaveCriticalSection(&section);     }
ErrorNext:
Flag=0;
PurgeComm(m_hCom,PURGE_TXABORT | PURGE_TXCLEAR | PURGE_RXABORT | PURGE_RXCLEAR);
}
 
}
return 1;
}

Answer 2

超时设置有问题，现在已经解决了！
但是还有一个问题，就是程序一运行，WaitCommEvent就能扑捉到串口有EV_RXCHAR事件，不知道什么原因？