#

# 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 doesn't
           seem  to  work.  Set  a  link  /dev/scanner  to the appropriate /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 1.0.12-cvs          07 Dec 2002                     sane-scsi(5)