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)
       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/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.


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.
       Information 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 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.


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
              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_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)
