kopia lustrzana https://gitlab.com/sane-project/backends
169 wiersze
6.6 KiB
Groff
169 wiersze
6.6 KiB
Groff
.TH sane-scsi 5 "15 Sep 2002"
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.IX sane-usb
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.SH NAME
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sane-usb - USB configuration tips for SANE
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.SH DESCRIPTION
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This manual page contains information on how to access scanners
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with a USB interface.
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.SH GENERAL INFO
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This manual page describes the access of USB scanners over the sanei_usb
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interface. Most SANE USB backends use the sanei_usb interface, only sm3600
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accesses the USB directly by libusb. Have a look at sane-sm3600 and section
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"LIBUSB ACCESS TIPS" of this manual page for that backend.
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.PP
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Two methods for accessing USB devices are used by sanei_usb: direct access
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using the kernel scanner driver and access over libusb. sanei_usb tries both
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methods, if they are available. Currently USB access is tested for Linux
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(kernel, libusb), FreeBSD (kernel, libsub), NetBSD (libusb), and OpenBSD
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(kernel, libusb). Libusb access should also work on Mac OS X (Darwin) and any
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other operating system supported by libusb but hasn't been tested yet. For
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installation issues, also check the @DOCDIR@/README.platform files.
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.PP
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Most backends will detect USB scanners automatically using "usb" configuration
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file lines. This method allows to identify scanners by the USB vendor and
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product numbers. The syntax for specifying a scanner this way is:
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.PP
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.RS
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usb
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.I VENDOR PRODUCT
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.RE
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.PP
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where
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.I VENDOR
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is the USB vendor id, and
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.I PRODUCT
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is the USB product id of the scanner. Both ids are non-negative integer
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numbers in decimal or hexadecimal format. The correct values for these fields
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can be found by looking into the syslog (e.g., /var/log/messages) or under
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Linux by issuing the command "cat /proc/bus/usb/devices/". This is an example
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of a config file line:
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.PP
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.RS
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usb 0x055f 0x0006
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.RE
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.PP
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would have the effect that all USB devices in the system with a vendor id of
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0x55f and a product id of 0x0006 would be probed and recognized by the
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backend. The same config line in decimal format looks like this:
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.PP
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.RS
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usb 1375 6
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.RE
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.PP
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If your scanner is not detected automatically, it may be necessary to edit the
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appropriate backend configuration file before using SANE for the first time.
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For most systems, the configuration file should list the name of the USB
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device file that the scanner is connected to (e.g., under Linux,
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.B /dev/usb/scanner0
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or
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.B /dev/usbscanner0
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is such a USB device, the device file for FreeBSD is e.g.
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.BR /dev/uscanner0 ).
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If libusb is used, the device name looks like the following example:
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.B libusb:001:002
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.PP
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Do
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.I not
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create a symlink from
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.B /dev/scanner
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to the USB device because this link is used by the SCSI backends. The scanner
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may be confused if it receives SCSI commands.
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.PP
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For a detailed description of each backend's configuration file, please refer
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to the relevant backend manual page (e.g. sane-mustek_usb for Mustek USB
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scanners).
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.PP
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.SH WHEN TO USE WHICH ACCESS METHOD
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Generally speaking, if your scanner works with one method, there is no need
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to switch to the other one.
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.PP
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Libusb is the more general approach and will be able to access any
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scanner. Also, it supports more platforms. However, the library must be
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available and installed on the system and setting permissions isn't easy at
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least on Linux.
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.PP
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Autodetecting scanners and using USB control messages with the kernel access
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method only works with recent (>=v2.4.12) Linux kernels. If you need one of
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these two features on a different platform, use libusb instead.
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.SH KERNEL SCANNER DRIVER TIPS
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Ensure that the access permissions for the USB device are set appropriately.
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We recommend to add a group "scanner" to /etc/group which contains all users
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that should have access to the scanner. The permission of the device should
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then be set to allow group read and write access. For example, if the scanner
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is at USB device
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.BR /dev/usb/scanner0 ,
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then the following two commands would set the permission correctly:
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.PP
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.RS
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$ chgrp scanner /dev/usb/scanner0
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.br
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$ chmod 660 /dev/usb/scanner0
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.RE
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.PP
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If your scanner isn't detected automatically by your operating system's
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scanner driver, you need to tell the kernel the vendor and product ids of your
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scanner. For
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.BR Linux ,
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this can be done with modprobe parameters: First, remove the scanner module
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(rmmod scanner), then load it again: modprobe scanner vendor=0x0001
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product=0x0002. Use the appropriate vendor and product ids (e.g. from syslog
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or cat /proc/bus/usb/devices). For OpenBSD the kernel must be recompiled. For
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details look at @DOCDIR@/README.openbsd. Similar approaches should be used for
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the other BSDs.
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.PP
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Linux kernel messages in syslog like "kernel: scanner.c: open_scanner(1):
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Unable to access minor data" can be ignored. They are generated when SANE
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scans all available USB devices for scanners.
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.SH LIBUSB ACCESS TIPS
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Libusb can only access your scanner if it's not claimed by the kernel scanner
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driver. If you want to use libusb, unload the kernel driver (e.g. rmmod
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scanner under Linux) or disable the driver when compiling a new kernel. For
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Linux, your kernel needs support for the USB filesystem (usbfs) and that
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filesystem must be mounted. That's done automatically, if /etc/fstab contains
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a line like this:
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.PP
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.RS
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none /proc/bus/usb usbfs defaults 0 0
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.RE
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.PP
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The permissions for the device files used by libusb must be adjusted for user
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access. Otherwise only root can use SANE devices. For
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.IR Linux ,
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the devices are located in /proc/bus/usb/. There are directories named
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e.g. "001" (the bus name) containing files "001", "002" etc. (the device
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files). The right device files can be found out by running scanimage -L as
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root. Setting permissions with "chmod" is not permanent, however. They will be
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resetted after reboot or replugging the scanner. It's also possible to mount
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the usbfs with the option "devmode=0666", e.g. by using the following line in
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/etc/fstab:
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.PP
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.RS
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none /proc/bus/usb usbfs defaults,devmode=0666 0 0
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.RE
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.PP
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However, this way everyone has access to all USB devices. Another way to set
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permissions is to use the hotplug utilities
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(http://linux-hotplug.sourceforge.net/), which support dynamic setting of
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access permissions. Last, the frontends can be run as root. However, that's
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not recommended for security reasons.
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.PP
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For the
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.IR BSDs ,
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the device files are named /dev/ugen*. Use chmod to apply appropriate
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permissions.
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.SH ENVIRONMENT
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.TP
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.B SANE_DEBUG_SANEI_USB
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If the library was compiled with debug support enabled, this
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environment variable controls the debug level for the USB I/O
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subsystem. E.g., a value of 128 requests all debug output to be
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printed. Smaller levels reduce verbosity. Values greater than 4 enable
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libusb debugging (if available).
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.SH "SEE ALSO"
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sane(7), sane\-find\-scanner(1), sane\-"backendname"(5), sane-scsi(5)
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.SH AUTHOR
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Henning Meier-Geinitz. Some parts were copied from the sane-scsi manual page.
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