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
       appropriate  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

       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
       access 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

       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
       detailed  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
       refer 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
                     encounter 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

              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
                     becomes  almost  unusable.   You may change the values of
                     the USLEEP macros in drivers/scsi/g_NCR5380.c.  Some doc-
                     umentation 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
                     advanced  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.

              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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