SetCommMask info  Overview  Group

The SetCommMask function specifies a set of events to be monitored for a communications device.

BOOL SetCommMask(

HANDLE hFile,	// handle of communications device
DWORD dwEvtMask	// mask that identifies enabled events
);

Parameters

hFile

Identifies the communications device. The CreateFile function returns this handle.

dwEvtMask

Specifies the events to be enabled. A value of zero disables all events. This parameter can be a combination of the following values:

Value	Meaning
EV_BREAK	A break was detected on input.
EV_CTS	The CTS (clear-to-send) signal changed state.
EV_DSR	The DSR (data-set-ready) signal changed state.
EV_ERR	A line-status error occurred. Line-status errors are CE_FRAME, CE_OVERRUN, and CE_RXPARITY.
EV_RING	A ring indicator was detected.
EV_RLSD	The RLSD (receive-line-signal-detect) signal changed state.
EV_RXCHAR	A character was received and placed in the input buffer.
EV_RXFLAG	The event character was received and placed in the input buffer. The event character is specified in the device’s DCB structure, which is applied to a serial port by using the SetCommState function.
EV_TXEMPTY	The last character in the output buffer was sent.

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

The SetCommMask function specifies the set of events that can be monitored for a particular communications resource. A handle to the communications resource can be specified in a call to the WaitCommEvent function, which waits for one of the events to occur. To get the current event mask of a communications resource, use the GetCommMask function.

If SetCommMask is called for a communications resource while an overlapped wait is pending for that resource, WaitCommEvent returns an error.

See Also

CreateFile, DCB, GetCommMask, SetCommState, WaitCommEvent