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sane-scsi(5)		 SANE Scanner Access Now Easy		  sane-scsi(5)

       sane-scsi - SCSI	adapter	tips for scanners

       This  manual  page  contains various operating-system specific tips and
       tricks on how to	get scanners with a SCSI interface working.

       For scanners with a SCSI	interface, it may be necessary to edit the ap-
       propriate  backend  configuration  file before using SANE for the first
       time.  For most systems,	the configuration file should list the name of
       the  generic  SCSI device that the scanner is connected to (e.g., under
       Linux, /dev/sg4 or /dev/sge is such a generic SCSI device).  It is cus-
       tomary to create	a symlink from /dev/scanner to the generic SCSI	device
       that the	scanner	is connected to.  In this case,	the configuration file
       simply lists the	line /dev/scanner.  For	a detailed description of each
       backend's configuration file, please refer to the relevant backend man-
       ual  page  (e.g.,  sane-epson(5)	 for Epson scanners, sane-hp(5)	for HP
       scanners, etc.).

       For some	operating systems (e.g.	Linux and OS/2), there is an alternate
       way  of specifying scanner devices.  This alternate way allows to iden-
       tify scanners by	the SCSI vendor	and model string and/or	 by  the  SCSI
       device address (consisting of bus number, channel number, id, and logi-
       cal unit	number).  The syntax for specifying a scanner in this way is:


       where VENDOR is the SCSI	vendor string, MODEL is	the SCSI model string,
       TYPE is type SCSI device	type string, BUS is the	SCSI bus number	(named
       "host" in /proc/scsi/scsi), CHANNEL is the SCSI channel number,	ID  is
       the  SCSI id, and LUN is	the logical unit number	of the scanner device.
       The first two fields are	strings	which  must  be	 enclosed  in  double-
       quotes  if  they	contain	any whitespace.	 The remaining four fields are
       non-negative integer numbers.  The correct values for these fields  can
       be  found  by  using operating system specific tools, e.g. for Linux by
       looking at the output of	the command "cat  /proc/scsi/scsi".   To  sim-
       plify  configuration,  a	field's	value can be replaced with an asterisk
       symbol (``*'').	An asterisk has	the effect that	any value  is  allowed
       for  that  particular  field.   This  can have the effect that a	single
       scsi-line matches multiple devices.  When this happens,	each  matching
       device  will  be	probed by the backend one by one and registered	if the
       backend thinks it is a compatible device.  For example, the line

	      scsi MUSTEK MFS-06000CX Scanner 0	00 03 00

       would attach the	Mustek SCSI scanner with the following /proc/scsi/scsi

	 Host: scsi0 Channel: 00 Id: 03	Lun: 00
	   Vendor: MUSTEK   Model: MFS-06000CX Rev: 4.04
	   Type:   Scanner  ANSI SCSI revision:	0

       Usually	it's  sufficient  to use vendor	and model strings only or even
       only the	vendor string. The following example

	      scsi MUSTEK * * *	* * *

       would have the effect that all SCSI devices in the system with a	vendor
       string of MUSTEK	would be probed	and recognized by the backend.

       If  the	remainder of a scsi-string consists of asterisks only, the as-
       terisks can be omitted.	For example, the following line	is  equivalent
       to the one specified previously:

	      scsi MUSTEK

       On  some	 platforms  (e.g., OpenStep), SANE device names	take a special
       form.  This is explained	below in the relevant  platform-specific  sec-

       When  using  a  SCSI scanner, ensure that the access permission for the
       generic SCSI device is set appropriately.  We recommend to add a	 group
       "scanner"  to  /etc/group which contains	all users that should have ac-
       cess to the scanner.  The permission of the device should then  be  set
       to  allow  group	read and write access.	For example, if	the scanner is
       at generic SCSI device /dev/sg0,	then the following two commands	 would
       set the permission correctly:

	      $	chgrp scanner /dev/sg0
	      $	chmod 660 /dev/sg0

       When  your  system uses the device filesystem (devfs), you have to edit
       /etc/devfs/perms.  There	you should search the line

	      REGISTER ^sg[^/]*	PERMISSIONS root.root 0600

       and add a new line (eg. for changing permissions	of sg4):

	      REGISTER ^sg4 PERMISSIONS	root.scanner 0660

       Auto-configuration using	the "scsi *" lines in the  config  files  only
       works  if  the  user  running  the  frontend  has  read/write  acces to
       /dev/xpt0. Instead, you can also	set a link /dev/scanner	to the	appro-
       priate /dev/uk device.

	      Adaptec AHA1542CF
		     Reported  to  work	fine under FreeBSD 2.2.2R with the aha

	      Adaptec 2940
		     Reported to work fine under FreeBSD 2.2.2.

	      Adaptec 1522
		     The scanner probes	ok but any attempt to access it	 hangs
		     the  entire  system. It looks like	something is disabling
		     interrupts	and then not re-enabling  them,	 so  it	 looks
		     like a bug	in the FreeBSD aic driver.

	      Adaptec 1505
		     Works  on	FreeBSD	 2.2.5R	 and 3.0 using the aic driver,
		     provided that Plug-and-Play support is  disabled  on  the
		     card.  If there are no uk devices,	just do	a ``sh MAKEDEV
		     uk0'' in the /dev directory. The scanner should  then  be
		     accessible	as /dev/uk0 if it was probed during boot.

	      Tekram DC390
		     Reported  to  work	fine under FreeBSD 2.2.2R with the amd

       First, make sure	your kernel has	 SCSI  generic	support	 enabled.   In
       ``make xconfig'', this shows up under ``SCSI support->SCSI generic sup-

       To keep scanning	times to a minimum, it is strongly recommended to  use
       a large buffer size for the generic SCSI	driver.	From SG	driver version
       2.0 on, the maximum buffer size can be changed at program run time, and
       there  is  no  restriction  in size. This driver	version	is part	of the
       Linux kernels from version 2.2.7	on. If the new SG driver is  available
       some  backends  (e.g. sane-umax,	sane-mustek, sane-sharp) automatically
       request larger scsi buffers. If a backend does  not  automatically  re-
       quest   a   larger   scsi   buffer,   set   the	 environment  variable
       SANE_SG_BUFFERSIZE to the desired buffer	size in	bytes. It is not  rec-
       ommended	 to use	more than 1 MB,	because	for large values the probabil-
       ity increases that the SG driver	cannot	allocate  the  necessary  buf-
       fer(s).	For ISA	cards, even 1 MB might be a too	large value. For a de-
       tailed  discussion  of  memory	issues	 of   the   SG	 driver,   see

       For  Linux  kernels before version 2.2.7	the size of the	buffer is only
       32KB.  This works, but for many cheaper scanners	this  causes  scanning
       to be slower by about a factor of four than when	using a	size of	127KB.
       Linux defines the size of this buffer by	macro  SG_BIG_BUFF  in	header
       file  /usr/include/scsi/sg.h.   Unless  a  system is seriously short on
       memory, it is recommended to increase this value	to the	maximum	 legal
       value  of  128*1024-512=130560 bytes.  After changing this value, it is
       necessary to recompile both the kernel (or the SCSI generic module) and
       the  SCSI backends. Keep	in mind	that this is only necessary with older
       Linux kernels.

       A common	issue with SCSI	scanners is what to do	when  you  booted  the
       system  while  the scanner was turned off?  In such a case, the scanner
       won't be	recognized by the kernel and SANE won't	be able	to access  it.
       Fortunately,  Linux  provides a simple mechanism	to probe a SCSI	device
       on demand.  Suppose you have a scanner connected	to SCSI	bus 2 and  the
       scanner	has a SCSI id of 5.  When the system is	up and running and the
       scanner is turned on, you can issue the command:

	      echo "scsi add-single-device 2 0 5 0" > /proc/scsi/scsi

       and the kernel will probe and recognize your scanner (this needs	to  be
       done  as	root).	It's also possible to dynamically remove a SCSI	device
       by using	the ``remove-single-device'' command.  For details, please re-
       fer to to the SCSI-2.4-HOWTO.

       Scanners	 are  known  to	 work  with  the following SCSI	adapters under
       Linux. This list	isn't complete,	usually	any SCSI adapter supported  by
       Linux should work.

	      Acard/Advance SCSI adapters
		     Some  old	versions  of the kernel	driver (atp870u.c) cut
		     the inquiry information.  Therefore the scanner  couldn't
		     be	detected correctly. Use	a current kernel.

	      Adaptec AHA-1505/AHA-1542/AHA-2940
		     Reported  to  work	fine with Linux	since v2.0. If you en-
		     counter kernel freezes or other unexpected	behaviour  get
		     the  latest Linux kernel (2.2.17 seems to work) or	reduce
		     SCSI buffer size to 32 kB.

	      ASUS SC200
		     Reported to work fine with	Linux v2.0.

	      BusLogic BT958
		     To	configure the BusLogic card, you may  need  to	follow
		     these     instructions	(contributed	 by	Jeremy
		     <>): During boot, when	your  BusLogic
		     adapter  is being initialized, press Ctrl-B to enter your
		     BusLogic adapter setup.  Choose the  address  which  your
		     BusLogic  containing  your	 scanner  is  located.	Choose
		     ``SCSI Device Configuration''.  Choose ``Scan SCSI	Bus''.
		     Choose  whatever  SCSI  id	that contains your scanner and
		     then choose ``View/Modify SCSI  configuration''.	Change
		     ``Negotiation'' to	``async'' and change ``Disconnect'' to
		     ``off''. Press Esc, save, and Esc	again  until  you  are
		     asked to reboot.

	      NCR/Symbios 53c400/53c400a or Domex DTC3181E/L/LE	(DTCT436/436P)
	      ISA SCSI card
		     This card is supplied by Mustek (and other	vendors). It's
		     supported	since Linux 2.2.  The SCSI cards are supported
		     by	the module g_NCR5380.  It's necessary to tell the ker-
		     nel the io	port and type of card.	Example	for a 53c400a:
		     ``modprobe	 g_NCR5380   ncr_addr=0x280   ncr_53c400a=1''.
		     Once  the	kernel	detects	 the  card, it should work all
		     right.  However, while it should work, do not expect good
		     performance  out  of this card---it has no	interrupt line
		     and therefore while a scan	is in progress,	the system be-
		     comes  almost unusable.  You may change the values	of the
		     USLEEP macros in drivers/scsi/g_NCR5380.c.	 Some documen-
		     tation is in this file and	NCR5380.c.

	      NCR/Symbios 810
		     For  some scanners	it may be necessary to disable discon-
		     nect/reconnect.  To   achieve   this   use	  the	option
		     ncr53c8xx="disc:n". Some people reported that their scan-
		     ner  only	worked	with  the  53c7,8xx  driver,  not  the
		     ncr53c8xx.	Try both if you	have trouble.
		     For  Linux	 kernels  before 2.0.33	it may be necessary to
		     increase the SCSI timeout.	The default  timeout  for  the
		     Linux  kernels  before 2.0.33 is 10 seconds, which	is way
		     too low when scanning large area.	If you get messages of
		     the  form	``restart (ncr dead ?)'' in your /var/log/mes-
		     sages file	or on the system console, it's	an  indication
		     that  the	timeout	 is too	short.	In this	case, find the
		     line ``if (np->latetime>10)'' in file  ncr53c8xx.c	 (nor-
		     mally   in	  directory  /usr/src/linux/drivers/scsi)  and
		     change the	constant 10 to,	say, 60	 (one  minute).	  Then
		     rebuild the kernel/module and try again.

	      Tekram DC315
		     The      driver	  can	   be	   downloaded	  from  For some	 older
		     scanners  it may be necessary to disable all the more ad-
		     vanced  features  by  using  e.g.	 modprobe   dc395x_trm

	      Tekram DC390
		     Version  1.11  of	the  Tekram  driver seems to work fine
		     mostly, except that the scan does not terminate  properly
		     (it causes	a SCSI timeout after 10	minutes).  The generic
		     AM53C974 also seems to work fine and does not suffer from
		     the timeout problems.

       Under  Solaris,	OpenStep  and  NeXTStep,  the generic SCSI device name
       refers to a SCSI	bus,  not  to  an  individual  device.	 For  example,
       /dev/sg0	 refers	 to  the first SCSI bus.  To tell SANE which device to
       use, append the character 'a'+target-id to  the	special	 device	 name.
       For example, the	SCSI device connected to the first SCSI	controller and
       with target-id 0	would be called	/dev/sg0a, and the device with target-
       id 1 on that same bus would be called /dev/sg0b,	and so on.

	      If the library was compiled with debug support enabled, this en-
	      vironment	variable controls the debug level for the generic SCSI
	      I/O  subsystem.	E.g., a	value of 128 requests all debug	output
	      to be printed by the backend. A value of 255 also	prints	kernel
	      messages	from  the  SCSI	 subsystem (where available).  Smaller
	      levels reduce verbosity.

	      sets the timeout value for SCSI commands in seconds.  Overriding
	      the  default  value  of 120 seconds should only be necessary for
	      very slow	scanners.

       sane(7),	sane-find-scanner(1), sane-"backendname"(5), sane-usb(5)

       David Mosberger

				  14 Jul 2008			  sane-scsi(5)


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