Specifies a set of events to be monitored for a communications device.

BOOLEAN SetCommMask(
  COMMHANDLE hComm,    // handle to communications device
  DWORD dwEvtMask      // mask that identifies enabled events
);

Parameters

hComm

[in] Handle to the communications device. OpenComm returns this handle.

dwEvtMask

[in] Specifies the events to be enabled. A value of zero disables all events. This parameter can be one or more of the following values:

Value	Description
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 SetCommState.
EV_TXEMPTY	The last character in the output buffer was sent.

Return Values

Non-zero

Success.

0 (zero)

Failure. To determine the status, call GetLastRtError.

Status

E_DISCONNECTED

COMM channel is closed.

E_PARAM

Invalid parameter.

Remarks

This 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 WaitCommEvent, which waits for one of the events to occur. To get the current event mask of a communications resource, use GetCommMask.

Requirements