Provided by: libsane-common_1.0.23-3ubuntu3.1_amd64 bug


       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 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) 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)