#

# 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 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
           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  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
                         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  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
                         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 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
           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 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
                         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

                                      14 Jul 2008                     sane-scsi(5)