ClearCommError

The ClearCommError function retrieves information about a communications error and reports the current status of a communications device. The function is called when a communications error occurs, and it clears the device's error flag to enable additional input and output (I/O) operations.

BOOL ClearCommError(
  HANDLE hFile,     // handle to communications device
  LPDWORD lpErrors, // pointer to variable to receive error codes
  LPCOMSTAT lpStat  // pointer to buffer for communications status
);
 

Parameters

hFile

Handle to the communications device. The CreateFile function returns this handle.

lpErrors

Pointer to a 32-bit variable to be filled with a mask indicating the type of error. This parameter can be one or more of the following error codes:

Value	Meaning
CE_BREAK	The hardware detected a break condition.
CE_DNS	Windows 95 and Windows 98: A parallel device is not selected.
CE_FRAME	The hardware detected a framing error.
CE_IOE	An I/O error occurred during communications with the device.
CE_MODE	The requested mode is not supported, or the hFile parameter is invalid. If this value is specified, it is the only valid error.
CE_OOP	Windows 95 and Windows 98: A parallel device signaled that it is out of paper.
CE_OVERRUN	A character-buffer overrun has occurred. The next character is lost.
CE_PTO	Windows 95 and Windows 98: A time-out occurred on a parallel device.
CE_RXOVER	An input buffer overflow has occurred. There is either no room in the input buffer, or a character was received after the end-of-file (EOF) character.
CE_RXPARITY	The hardware detected a parity error.
CE_TXFULL	The application tried to transmit a character, but the output buffer was full.

lpStat

Pointer to a COMSTAT structure in which the device's status information is returned. If lpStat is NULL, no status information is returned.

Return Values

If the function succeeds, the return value is nonzero.

If the function fails, the return value is zero. To get extended error information, call GetLastError.

Remarks

If a communications port has been set up with a TRUE value for the fAbortOnError member of the setup DCB structure, the communications software will terminate all read and write operations on the communications port when a communications error occurs. No new read or write operations will be accepted until the application acknowledges the communications error by calling the ClearCommError function.

The ClearCommError function fills the status buffer pointed to by the lpStat parameter with the current status of the communications device specified by the hFile parameter.

QuickInfo

  Windows NT: Requires version 3.1 or later.
  Windows: Requires Windows 95 or later.
  Windows CE: Requires version 1.0 or later.
  Header: Declared in winbase.h.
  Import Library: Use kernel32.lib.

See Also

Communications Overview, Communication Functions, ClearCommBreak, COMSTAT, CreateFile, DCB