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

       sane-usb	- USB configuration tips for SANE

       This  manual page contains information on how to	access scanners	with a
       USB interface. It focusses on two main topics: getting the scanner  de-
       tected 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.

       This is a short HOWTO-like section. For the full	details, read the fol-
       lowing  sections.  The  goal  of	this section is	to get the scanner de-
       tected 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).

       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.

       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

	      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 permis-
       sions 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/lo-
       cal/share/doc/sane-backends/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.

       This  section  assumes that your	scanner	is detected by sane-find-scan-
       ner. 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
       (, and the individual backend manpages.

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


       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/mes-
       sages)  or  under  Linux	 by issuing the	command	"cat /proc/bus/usb/de-
       vices".	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 recognized
       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  configu-
       ration  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.

	      If the library was compiled with debug support enabled, this en-
	      vironment	variable controls the debug level for the USB I/O sub-
	      system.  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_DE-

	      If your scanner does not work when plugged into a	USB3 port, try
	      setting the environment variable SANE_USB_WORKAROUND to 1.  This
	      may  work	around issues which happen with	particular kernel ver-
	      sions. Example: export SANE_USB_WORKAROUND=1.

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

       Henning Meier-Geinitz <>

				  14 Jul 2008			   sane-usb(5)


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