GetCommModemStatus
The GetCommModemStatus
function retrieves modem control-register values.
BOOL GetCommModemStatus(
|
HANDLE hFile, |
// handle of
communications device |
|
LPDWORD lpModemStat |
// address of
control-register values |
|
); |
|
Parameters
hFile
Identifies
the communications device. The CreateFile function returns this handle.
lpModemStat
Points to a
32-bit variable that specifies the current state of the modem control-register
values. This parameter can be a combination of the following values:
|
Value |
Meaning |
|
MS_CTS_ON |
The CTS
(clear-to-send) signal is on. |
|
MS_DSR_ON |
The DSR
(data-set-ready) signal is on. |
|
MS_RING_ON |
The ring
indicator signal is on. |
|
MS_RLSD_ON |
The RLSD
(receive-line-signal-detect) signal is on. |
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 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.
See Also