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 de-
tected 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 Scan-
ners supported by the sane-microtek2(5) backend need a special USB ker-
nel driver.
QUICK START
This is a short HOWTO-like section. For the full details, read the fol-
lowing 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 de-
tails 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/hot-
plug. They can be used for setting permissions, see /usr/share/doc/lib-
sane/README.linux, tools/README and the README in the tools/hotplug di-
rectory for more details.
For the BSDs, the device files used by libusb are named /dev/ugen*. Use
chmod(1) to apply appropriate permissions.
SANE ISSUES
This section assumes that your scanner is detected by sane-find-scan-
ner(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. Informa-
tion 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" configu-
ration 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 configura-
tion 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 re-
ceives SCSI commands.
ENVIRONMENT
SANE_DEBUG_SANEI_USB
If the library was compiled with debug support enabled, this en-
vironment variable controls the debug level for the USB I/O sub-
system. 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_DE-
BUG_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 ver-
sions. Example: export SANE_USB_WORKAROUND=1.
SANE_XEROX_USB_HALT_WORKAROUND
If your old (pre-2010) Xerox / Samsung / HP scanner is detected
only once and subsequent usage requires replugging the cable, try
setting the environment variable SANE_XEROX_USB_HALT_WORKAROUND
to 1. This may work around issues which happen with particular
USB controllers. Example: export SANE_XE-
ROX_USB_HALT_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)
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