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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	one to
       identify	scanners by the	SCSI vendor and	model  string  and/or  by  the
       SCSI  device address (consisting	of bus number, channel number, id, and
       logical unit number).  The syntax for specifying	a scanner in this  way


       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 simplify
       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  access  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 ac-
		     cessible 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 support''.

       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(5), sane-mustek(5), sane-sharp(5)) auto-
       matically request larger	SCSI buffers. If a backend does	not  automati-
       cally  request  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 perfor-
		     mance  out	 of  this  card---it has no interrupt line and
		     therefore while a scan is in progress, the	system becomes
		     almost  unusable. You may change the values of the	USLEEP
		     macros in drivers/scsi/g_NCR5380.c.   Some	 documentation
		     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.	 (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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