#

# sane-scsi.5

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

## NAME

           sane-scsi - SCSI adapter tips for scanners

## DESCRIPTION

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

## GENERAL INFO

           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:

                  scsi VENDOR MODEL TYPE BUS CHANNEL ID LUN

           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
           entry:

             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
           asterisks can be omitted.  For example, the following line  is  equiva-
           lent 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-
           tion.

           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

## FREEBSD INFO

           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
                         driver.

                  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 reenabling 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
                         driver.

## LINUX INFO

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

           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
           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
           buffer(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
           http://www.torque.net/sg.

           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
                         To configure the BusLogic card, you may  need  to  follow
                         these     instructions     (contributed     by     Jeremy
                         <jeremy@xxedgexx.com>): 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
                         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 necssary 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
                         http://www.garloff.de/kurt/linux/dc395/.   For some older
                         scanners it may be necessary  to  disable  all  the  more
                         advanced  features  by  using  e.g.  modprobe  dc395x_trm
                         dc395x_trm=7,5,1,32.

                  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.

## SOLARIS, OPENSTEP AND NEXTSTEP INFO

           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.

## ENVIRONMENT

           SANE_DEBUG_SANEI_SCSI
                  If the library was compiled with  debug  support  enabled,  this
                  environment  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.

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

## SEE ALSO

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

## AUTHOR

           David Mosberger

    sane-backends 1.0.13              28 Oct 2003                     sane-scsi(5)