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