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 focuses 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 exception: USB Scan-
       ners supported by the sane-microtek2(5) backend need a special USB ker-
       nel driver.


       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
       detected by sane-find-scanner(1).

       Run sane-find-scanner(1).  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(1) doesn't list your scanner? Does it work  as  root?
       If  yes,  there  is  a  permission  issue.   See the LIBUSB section for

       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  per-
       missions  with  chmod(1)  is not permanent, however. They will be reset
       after reboot or replugging the scanner.

       Usually udev(7) 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/local/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(1).  It doesn't make sense to go on, if this is not the case. While
       sane-find-scanner(1) 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:

              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(1),   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  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
              environment variable controls the debug level for  the  USB  I/O
              subsystem.  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

              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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