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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 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
       /opt/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(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.



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)

sane-backends 1.2.1 - Generated Sat Feb 25 10:16:53 CST 2023
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