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UINT __cdecl OnWatchCom(LPVOID lparam)
{
CBillDlg *pDlg = (CBillDlg *)lparam;
if(pDlg == NULL) return -1;
CString strResult;
char buff[128] = {0};
while(pDlg->m_IsWatching)
{
if(pDlg->m_Com.ReadCom(buff,128,2000))
{
pDlg->m_Com.ClearComBuf(PURGE_TXABORT | PURGE_RXABORT | PURGE_TXCLEAR | PURGE_RXCLEAR);
strResult.Format(_T("%s"),buff);
if(!strResult.IsEmpty())
{
pDlg->m_strBillNo = strResult;
pDlg->UpdateData(0);
}
}
Sleep(50);
}
return 0;
}
BOOL CComport::ReadCom(char *buff, int nlen, int dwMiniTimeout)
{
if(!IsOpen()) return FALSE;
OVERLAPPED m_osRead;
memset(&m_osRead,0,sizeof(OVERLAPPED));
m_osRead.hEvent=CreateEvent(NULL,TRUE,FALSE,NULL);
COMSTAT ComStat;
DWORD dwErrorFlags;
memset(buff,'\0',nlen);
DWORD dwBytesRead=nlen;//读取的字节数
BOOL bReadStat;
ClearComErr(&dwErrorFlags,&ComStat);
dwBytesRead=min(dwBytesRead, (DWORD)ComStat.cbInQue);
bReadStat=ReadFile(m_hCom,buff,dwBytesRead,&dwBytesRead,&m_osRead);
if(!bReadStat)
{
if(GetLastError()==ERROR_IO_PENDING)//GetLastError()函数返回ERROR_IO_PENDING,表明串口正在进行读操作
{
//GetOverlappedResult(m_hCom,&m_osRead,&dwBytesRead,TRUE);
WaitForSingleObject(m_osRead.hEvent,dwMiniTimeout);
//使用WaitForSingleObject函数等待,直到读操作完成或延时已达到2秒钟
//当串口读操作进行完毕后,m_osRead的hEvent事件会变为有信号
//ResetEvent(m_osRead.hEvent);
}
}
CloseHandle(m_osRead.hEvent);
return TRUE;
}