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.

ValueMeaning
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

Minimum supported client

Windows XP

Minimum supported server

Windows Server 2003

Header

Winbase.h (include Windows.h)

Library

Kernel32.lib

DLL

Kernel32.dll

See also

Communications Functions
Communications Resources
CreateFile
WaitCommEvent

 

 

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