Any MFP device may be connected to host computer via parallel port or USB port. Since the MFP device contains more than one device in a single case (printer and scanner), it's necessary to organize proper access of "consumer" applications to these devices via single I/O port. Currently MFP devices cannot be used for simultaneous printing and scanning, only one of the operations can proceed at once. If, for example, a printer's job has been started, scanning is impossible until the printer's job is finished. And vice versa, a document cannot be printed while scanning session is in progress.
The Unified Linux Driver package provides appropriate port sharing mechanism that is used by printer and scanner drivers. The drivers address their devices via so-called MFP ports. Current status of any MFP port can be viewed by Checking MFP ports status. The port sharing prevents from accessing one functional block of the MFP device, while another block is in use.
When you install a new MFP printer onto your system, it is strongly recommended to do this with assistance of MFP Configurator. In this case you will be offered to choose I/O port for the new device among MFP ports solely. This choice shall provide the most suitable configuration for MFP functionality. For MFP scanners I/O ports are being chosen by scanner driver automatically, so proper settings are applied by default.
See also:
Ports configuration