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#define MESSAGELENGTH 100
class CMyDialog : public CDialog
{
protected:
VARIANT InBuffer;
VARIANT OutBuffer;
CMSComm m_Com;
public:
......
}
BOOL CMyDiaLog::OnInitDialog()
{
CDialog::OnInitDialog();
m_Com.SetCommPort(1);
if (!m_Com.GetPortOpen()) {
m_Com.SetSettings("57600,N,8,1");
m_Com.SetPortOpen(true);
m_Com.SetInBufferCount(0);
SetTimer(1,10,NULL);
InBuffer.bstrVal=new unsigned short[MESSAGELENGTH];
OutBuffer.bstrVal=new unsigned short[MESSAGELENGTH];
OutBuffer.vt=VT_BSTR;
}
return true;
}
void CMyDiaLog::OnTimer(UINT nIDEvent)
{
if (m_Com.GetInBufferCount()>=MESSAGELENGTH) {
InBuffer=m_Com.GetInput();
// handle the InBuffer.
// Fill the OutBuffer.
m_Com.SetOutput(OutBuffer);
}
CDialog::OnTimer(nIDEvent);
}

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typedef struct _COMMTIMEOUTS {
DWORD ReadIntervalTimeout;
DWORD ReadTotalTimeoutMultiplier;
DWORD ReadTotalTimeoutConstant;
DWORD WriteTotalTimeoutMultiplier;
DWORD WriteTotalTimeoutConstant;
} COMMTIMEOUTS,*LPCOMMTIMEOUTS;

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typedef struct _OVERLAPPED {
DWORD Internal;
DWORD InternalHigh;
DWORD Offset;
DWORD OffsetHigh;
HANDLE hEvent;
} OVERLAPPED;

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BOOL CSerial::Open( int nPort, int nBaud )
{
if( m_bOpened ) return( TRUE );
char szPort[15];
DCB dcb;
wsprintf( szPort, "COM%d", nPort );
m_hComDev = CreateFile( szPort, GENERIC_READ | GENERIC_WRITE, 0, NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL | FILE_FLAG_OVERLAPPED, NULL );
if( m_hComDev == NULL ) return( FALSE );
memset( &m_OverlappedRead, 0, sizeof( OVERLAPPED ) );
memset( &m_OverlappedWrite, 0, sizeof( OVERLAPPED ) );
COMMTIMEOUTS CommTimeOuts;
CommTimeOuts.ReadIntervalTimeout = 0xFFFFFFFF;
CommTimeOuts.ReadTotalTimeoutMultiplier = 0;
CommTimeOuts.ReadTotalTimeoutConstant = 0;
CommTimeOuts.WriteTotalTimeoutMultiplier = 0;
CommTimeOuts.WriteTotalTimeoutConstant = 5000;
SetCommTimeouts( m_hComDev, &CommTimeOuts );
m_OverlappedRead.hEvent = CreateEvent( NULL, TRUE, FALSE, NULL );
m_OverlappedWrite.hEvent = CreateEvent( NULL, TRUE, FALSE, NULL );
dcb.DCBlength = sizeof( DCB );
GetCommState( m_hComDev, &dcb );
dcb.BaudRate = nBaud;
dcb.ByteSize = 8;
if( !SetCommState( m_hComDev, &dcb ) ||
!SetupComm( m_hComDev, 10000, 10000 ) ||
m_OverlappedRead.hEvent == NULL ||
m_OverlappedWrite.hEvent == NULL ){
DWORD dwError = GetLastError();
if( m_OverlappedRead.hEvent != NULL ) CloseHandle( m_OverlappedRead.hEvent );
if( m_OverlappedWrite.hEvent != NULL ) CloseHandle( m_OverlappedWrite.hEvent );
CloseHandle( m_hComDev );
return FALSE;
}
m_bOpened = TRUE;
return m_bOpened;
}
int CSerial::InBufferCount( void )
{
if( !m_bOpened || m_hComDev == NULL ) return( 0 );
DWORD dwErrorFlags;
COMSTAT ComStat;
ClearCommError( m_hIDComDev, &dwErrorFlags, &ComStat );
return (int)ComStat.cbInQue;
}
DWORD CSerial::ReadData( void *buffer, DWORD dwBytesRead)
{
if( !m_bOpened || m_hComDev == NULL ) return 0;
BOOL bReadStatus;
DWORD dwErrorFlags;
COMSTAT ComStat;
ClearCommError( m_hComDev, &dwErrorFlags, &ComStat );
if( !ComStat.cbInQue ) return 0;
dwBytesRead = min(dwBytesRead,(DWORD) ComStat.cbInQue);
bReadStatus = ReadFile( m_hComDev, buffer, dwBytesRead, &dwBytesRead, &m_OverlappedRead );
if( !bReadStatus ){
if( GetLastError() == ERROR_IO_PENDING ){
WaitForSingleObject( m_OverlappedRead.hEvent, 2000 );
return dwBytesRead;
}
return 0;
}
return dwBytesRead;
}
DWORD CSerial::SendData( const char *buffer, DWORD dwBytesWritten)
{
if( !m_bOpened || m_hComDev == NULL ) return( 0 );
BOOL bWriteStat;
bWriteStat = WriteFile( m_hComDev, buffer, dwBytesWritten, &dwBytesWritten, &m_OverlappedWrite );
if( !bWriteStat){
if ( GetLastError() == ERROR_IO_PENDING ) {
WaitForSingleObject( m_OverlappedWrite.hEvent, 1000 );
return dwBytesWritten;
}
return 0;
}
return dwBytesWritten;
}

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