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       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
       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.


       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).


       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)
       containing files "001", "002" etc. (the device files). The right device
       files  can  be  found  out  by  running  scanimage  -L as root. Setting
       permissions 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/libsane/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-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.
       Information  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"
       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 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
       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.


              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


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


       Henning Meier-Geinitz <>

                                  14 Jul 2008                      sane-usb(5)