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4/8/2010

This function waits for an event to occur for a specified communications device.

The set of events monitored by WaitCommEventis contained in the event mask associated with the device handle.

Syntax 

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

Parameters

hFile

[in] Handle to the communications device, returned by the CreateFilefunction.

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 values in the following table.

Value Description

EV_BREAK

A break was detected on input.

EV_CTS

The clear-to-send (CTS) signal changed state.

EV_DSR

The data-set-ready (DSR) 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.

This value is specific to Windows Embedded CE.

EV_RING

A ring indicator was detected.

EV_RLSD

The receive-line-signal-detect (RLSD) 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 DCBstructure, which is applied to a serial port by using the SetCommStatefunction.

EV_TXEMPTY

The last character in the output buffer was sent.
lpOverlapped

[in] Ignored; set to NULL.

Return Value

Nonzero indicates success. Zero indicates failure. To obtain extended error information, call the GetLastErrorfunction.

Remarks

The WaitCommEventfunction monitors a set of events for a specified communications resource. To set and query the current event mask of a communications resource, use the SetCommMaskand GetCommMaskfunctions. When a communications event that is set by SetCommMaskoccurs, WaitCommEventreturns.

Only one WaitCommEventcan be used for each open COM port handle. This means that if you have three threads in your application and each thread needs to wait on a specific comm event, each thread needs to open the COM port and then use the assigned port handle for their respective WaitCommEventcalls.

Requirements

Header winbase.h
Library Serdev.lib
Windows Embedded CE Windows CE 1.0 and later
Windows Mobile Windows Mobile Version 5.0 and later

See Also