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 the 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   the    Linux    SG    SCSI    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.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)

Man(1) output converted with man2html