sane-usb(5)						   SANE Scanner Access Now Easy 					       sane-usb(5)

NAME

       sane-usb - USB configuration tips for SANE

DESCRIPTION

       This  manual  page contains information on how to access scanners with a USB interface. It focusses on two main topics: getting the scanner
       detected by the operating system kernel and using it with SANE.

       This page applies to USB most backends and scanners, as they use the generic sanei_usb interface. However, there  is  one  exceptions:  USB
       Scanners supported by the microtek2 backend need a special USB kernel driver, see sane-microtek2(5) for details.

QUICK START

       This  is  a  short  HOWTO-like  section.  For the full details, read the following sections. The goal of this section is to get the scanner
       detected by sane-find-scanner(1).

       Run sane-find-scanner. If it lists your scanner with the correct vendor and product ids, you are done. See section SANE ISSUES for  details
       on how to go on.

       sane-find-scanner doesn't list your scanner? Does it work as root? If yes, there is a permission issue. See the LIBUSB section for details.

       Nothing is found even as root? Check that your kernel supports USB and that libusb is installed (see section LIBUSB).

USB ACCESS METHODS

       For  accessing  USB  devices,  the USB library libusb is used. There used to exist another method to access USB devices: the kernel scanner
       driver. The kernel scanner driver method is deprecated and shouldn't be used anymore. It may be removed from SANE at any  time.	In  Linux,
       the kernel scanner driver has been removed in the 2.6.* kernel series. Only libusb access is documented in this manual page.

LIBUSB

       SANE  can  only	use  libusb 0.1.6 or newer. It needs to be installed at build-time. Modern Linux distributions and other operating systems
       come with libusb.

       Libusb can only access your scanner if it's not claimed by the kernel scanner driver. If you want to use libusb, unload the  kernel  driver
       (e.g.  rmmod  scanner  under  Linux)  or  disable  the driver when compiling a new kernel. For Linux, your kernel needs support for the USB
       filesystem (usbfs). For kernels older than 2.4.19, replace "usbfs" with "usbdevfs" because the name has changed. This  filesystem  must	be
       mounted. That's done automatically at boot time, if /etc/fstab contains a line like this:

	      none /proc/bus/usb usbfs defaults  0  0

       The  permissions for the device files used by libusb must be adjusted for user access. Otherwise only root can use SANE devices. For Linux,
       the devices are located in /proc/bus/usb/ or in /dev/bus/usb, if you use udev. There are directories named e.g. "001" (the bus  name)  con-
       taining	files  "001", "002" etc. (the device files). The right device files can be found out by running scanimage -L as root. Setting per-
       missions with "chmod" is not permanent, however. They will be reset after reboot or replugging the scanner.

       Usually udev or for older distributions the hotplug utilities are used, which support dynamic setting of  access  permissions.  SANE  comes
       with  udev  and	hotplug  scripts  in  the  directory  tools/udev  and  tools/hotplug.  They  can  be  used  for  setting  permissions, see
       /usr/share/doc/sane-backends-1.0.24/README.linux, tools/README and the README in the tools/hotplug directory for more details.

       For the BSDs, the device files used by libusb are named /dev/ugen*.  Use chmod to apply appropriate permissions.

SANE ISSUES

       This section assumes that your scanner is detected by sane-find-scanner. It doesn't make sense to go on, if this is  not  the  case.  While
       sane-find-scanner is able to detect any USB scanner, actual scanning will only work if the scanner is supported by a SANE backend. Informa-
       tion on the level of support can be found on the SANE webpage (http://www.sane-project.org/), and the individual backend manpages.

       Most backends can detect USB scanners automatically using "usb" configuration file lines. This method allows to identify  scanners  by  the
       USB vendor and product numbers.	The syntax for specifying a scanner this way is:

	      usb VENDOR PRODUCT

       where  VENDOR  is the USB vendor id, and PRODUCT is the USB product id of the scanner. Both ids are non-negative integer numbers in decimal
       or hexadecimal format. The correct values for these fields can be found by  running  sane-find-scanner,	looking  into  the  syslog  (e.g.,
       /var/log/messages) or under Linux by issuing the command "cat /proc/bus/usb/devices".  This is an example of a config file line:

	      usb 0x055f 0x0006

       would  have  the  effect that all USB devices in the system with a vendor id of 0x55f and a product id of 0x0006 would be probed and recog-
       nized by the backend.

       If your scanner is not detected automatically, it may be necessary to edit the appropriate backend configuration file before using SANE for
       the  first  time.   For a detailed description of each backend's configuration file, please refer to the relevant backend manual page (e.g.
       sane-mustek_usb(5) for Mustek USB scanners).

       Do not create a symlink from /dev/scanner to the USB device because this link is used by the SCSI backends. The scanner may be confused	if
       it receives SCSI commands.

ENVIRONMENT

       SANE_DEBUG_SANEI_USB
	      If  the  library was compiled with debug support enabled, this environment variable controls the debug level for the USB I/O subsys-
	      tem.  E.g., a value of 128 requests all debug output to be printed.  Smaller levels reduce verbosity. Values greater than  4  enable
	      libusb debugging (if available). Example: export SANE_DEBUG_SANEI_USB=4.

SEE ALSO

       sane(7), sane-find-scanner(1), sane-"backendname"(5), sane-scsi(5)

AUTHOR

       Henning Meier-Geinitz <henning@meier-geinitz.de>

								    14 Jul 2008 						       sane-usb(5)