Operation

The IOCTL_SERIAL_GET_MODEM_CONTROL request returns the value of the modem control register.

To set the modem control register, a client can use an IOCTL_SERIAL_SET_MODEM_CONTROL request.

For information about modem control register settings, see the constants SERIAL_MCR_DTR through SERIAL_MCR_LOOP, which are defined in the header file \src\kernel\serial\serial.h in the Microsoft Windows Driver Kit (WDK).

Input

The Parameters.DeviceIoControl.OutputBufferLength is set to the size in bytes of a ULONG.

Output

The AssociatedIrp.SystemBuffer points to a client-allocated ULONG buffer that Serial uses to output the value of the modem control register.

I/O Status Block

If the request is successful, the Information member is set to the size in bytes of a ULONG. Otherwise, the Information member is set to zero.

The Status member is set to one of the Generic Status Values for Serial Device Control Requests.

Requirements

Headers: Defined in ntddser.h. Include ntddser.h.

See Also

IOCTL_SERIAL_SET_MODEM_CONTROL