GetCommModemStatus function

Retrieves the modem control-register values.

Syntax

BOOL WINAPI GetCommModemStatus(
  _In_  HANDLE  hFile,
  _Out_ LPDWORD lpModemStat
);

Parameters

hFile [in]

A handle to the communications device. The CreateFile function returns this handle.

lpModemStat [out]

A pointer to a variable that receives the current state of the modem control-register values. This parameter can be one or more of the following values.

Value	Meaning
MS_CTS_ON 0x0010	The CTS (clear-to-send) signal is on.
MS_DSR_ON 0x0020	The DSR (data-set-ready) signal is on.
MS_RING_ON 0x0040	The ring indicator signal is on.
MS_RLSD_ON 0x0080	The RLSD (receive-line-signal-detect) signal is on.

 

Return value

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 GetCommModemStatus function is useful when you are using the WaitCommEvent function to monitor the CTS, RLSD, DSR, or ring indicator signals. To detect when these signals change state, use WaitCommEvent and then use GetCommModemStatus to determine the state after a change occurs.

The function fails if the hardware does not support the control-register values.

Requirements

See also

Communications Functions

Communications Resources

CreateFile

WaitCommEvent