Ubuntu Manpage: sane-usb - USB configuration tips for SANE

NAME

       sane-usb - USB configuration tips for SANE

DESCRIPTION

       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   Scanners   supported   by   the
       sane-microtek2(5) backend need a special USB kernel driver.

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(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 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(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/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.

SANE ISSUES

This section assumes that your scanner is detected by sane-find-scanner(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. 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 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 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.

       SANE_USB_WORKAROUND
              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 versions. Example: export SANE_USB_WORKAROUND=1.

AUTHOR

       Henning Meier-Geinitz <henning@meier-geinitz.de>

                                           14 Jul 2008                                sane-usb(5)