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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 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  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
		     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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