usblp(HW)

usb_prnt- USB Printer Device Name Conventions

Description

   ls -tr /dev/usb_prnt* /dev/usblp*

The device node names are defined as follows:

/dev/usb_prnt#

The # appearing in the device name is the order the printer was recognized as attached. If you have only one printer, it will always be at /dev/usb_prnt0 regardless of how it is physically connected. If you have multiple USB printers connected (which is not currently supported), the digits at the end should not be regarded as stable: they will change as, for example, device timing varies and configuration changes are made.

/dev/usblp-#####-[###.###.###.###.###.]###

The first five digit number is the location of the host controller interface (HCI) to which the printer is connected. It's five digits represent the PCI bus number (two digits), the PCI device number (two digits), and the PCI function number (the final digit). For example:

   /dev/usblp-00072-1.4.2

The above device name indicates that the HCI is located at PCI bus number 00, PCI device 07, PCI function 2. Note that this number is completely determined by the hardware vendor's PCI configuration.

The remainder of the device name after the second dash is a sequence of from one to six decimal numbers, each of which can be from one to three digits. The final number, which is required, indicates the port number on the device to which the printer is physically connected. Up to five hubs can be connected between the printer and the PC USB port, and the ports to which these devices are connected are indicated by the five optional three digit numbers in the device name, separated by periods.

For example, if a USB printer were connected directly to the first USB port on the system, the device name might look like this:

   /dev/usblp-00072-1

A device name like /dev/usblp-00072-1.4.2 indicates the following device configuration:

   PC USB Port 1 --- | Hub#1 Port 1
   PC USB Port 2     | Hub#1 Port 2
                     | Hub#1 Port 3
                     | Hub#1 Port 4  --- | Hub#2 Port 1
                     ...                 | Hub#2 Port 2  --- USB Printer
                                         ...

where Hub#1 is connected into the system's first USB port, a second hub is plugged into Hub#1 Port 4, and the USB Printer is plugged into Hub#2 Port 2. This device name is completely unique and will not change as long as the physical configuration of the USB devices is not changed.