IOCTL_SERIAL_GET_MODEMSTATUS IOCTL

The IOCTL_SERIAL_GET_MODEMSTATUS request updates the modem status, and returns the value of the modem status register before the update.

For more information, see the definitions of the modem status register bits (SERIAL_MSR_DCTS through SERIAL_MSR_DCD) in the Serial.h header file in the Serial driver sample on GitHub.

Major Code

IRP_MJ_DEVICE_CONTROL

Input Buffer

None.

Input Buffer Length

None.

Output Buffer

The AssociatedIrp.SystemBuffer member points to a client-allocated ULONG buffer that the serial controller driver uses to output the value of the modem status register.

Output Buffer Length

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

Input / Output Buffer

Input / Output Buffer Length

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

   
Header ntddser.h (include Ntddser.h)

See Also

IOCTL_SERIAL_SET_MODEM_CONTROL