The IRP_MJ_CREATE request opens a serial device.
A client must open a serial device before it can access the port or a device connected to the port.
I/O Status Block
The Information field is set to zero.
The Status field is set to one of the following values:
The serial device was successfully opened.
The device is already open.
Serial is in the process of removing the device.
The device is not in a Plug and Play Started state, or the driver could not allocate an internal data structure.
A serial device cannot be opened as a directory.
Serial queued the request for later processing.
The interrupt assigned to the device is in use by another open device.
A serial device must be opened before it can be used. A serial device is an exclusive device; only one file can be open on a port at any given time.