WaitCommEvent

  • Article

This function waits for an event to occur for a specified communications device. The set of events that are monitored by WaitCommEvent is contained in the event mask associated with the device handle.

BOOL WaitCommEvent(
HANDLE hFile, 
LPDWORD lpEvtMask, 
LPOVERLAPPED lpOverlapped);

Parameters

  • hFile
    [in] Handle to the communications device. The CreateFile function returns this handle.

  • lpEvtMask
    [out] Long pointer to a 32-bit variable that receives a mask indicating the events that occurred. If an error occurs, the value is zero; otherwise, it is 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_POWER Power event, which is generated whenever the device is powered on.
    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.

  • lpOverlapped
    [in] Ignored; set to NULL.

Return Values

Nonzero indicates success. Zero indicates failure. To get extended error information, call GetLastError.

Remarks

The WaitCommEvent function monitors a set of events for a specified communications resource. To set and query the current event mask of a communications resource, use the SetCommMask and GetCommMask functions. When a communications event that is set by SetCommMask occurs, WaitCommEvent returns.

Requirements

Runs On Versions Defined in Include Link to
Windows CE OS 1.0 and later Winbase.h   Serdev.lib

Note   This API is part of the complete Windows CE OS package as provided by Microsoft. The functionality of a particular platform is determined by the original equipment manufacturer (OEM) and some devices may not support this API.

See Also

CreateFile, DCB, GetCommMask, GetLastError, SetCommMask, SetCommState

 Last updated on Tuesday, July 13, 2004

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