sane-scsi - SCSI adapter tips for scanners
DESCRIPTION
This manual page contains various operating-system spe
cific 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 con
figuration 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 customary 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 manual page (e.g.,
sane-epson(5) for Epson scanners, sane-hp(5) for HP scan
ners, etc.).
For Linux, there is an alternate way of specifying scanner
devices (beginning with SANE version 0.73). This alter
nate way is based on /proc/scsi/scsi and 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 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, 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-nega
tive integer numbers. The correct values for these fields
can be found 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 compati
ble device. For example, the line
scsi MUSTEK * * * * * *
with a vendor string of MUSTEK would be probed and recog
nized by the backend.
If the remainder of a scsi-string consists of asterisks
only, the asterisks can be omitted. For example, the fol
lowing 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 section.
When using a SCSI scanner, ensure that the access permis
sion 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/sge, then the following two
commands would set the permission correctly:
$ chgrp scanner /dev/sge
$ chmod 660 /dev/sge
FreeBSD
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 sup
port 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.
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 recom
mended 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 recommended to
use more than 1 MB, because for large values the probabil
ity increases that the SG driver cannot allocate the nec
essary 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 fac
tor 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 dynami
cally remove a SCSI device by using the ``remove-single-
device'' command. For details, please refer to to the
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 versions of the kernel driver
(atp870u.c) cut the inquiry information.
Therefore the scanner can't be detected cor
rectly. See http://www.meier-
geinitz.de/sane/trouble.html#acard for a
solution.
Adaptec AHA-1505/AHA-1542/AHA-2940
Reported to work fine with Linux v2.0. If
you encounter kernel freezes or other unex
pected 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 initial
ized, press Ctrl-B to enter your BusLogic
adapter setup. Choose the address which
your BusLogic containing your scanner is
located. Choose ``SCSI Device Configura
tion''. Choose ``Scan SCSI Bus''. Choose
whatever SCSI id that contains your scanner
and then choose ``View/Modify SCSI configu
ration''. 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). If you use Linux 2.0.x you may
need a patch from Ingmar Baumgart's home
page:
http://rzstud1.rz.uni-karl
sruhe.de/~uh49/mustek-scsi.html
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
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 there
fore 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 documenta
tion is in this file and NCR5380.c.
NCR/Symbios 810
For some scanners it may be necssary to dis
able disconnect/reconnect. To achieve this
use the option ncr53c8xx="disc:n".
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 mes
sages of the form ``restart (ncr dead ?)''
in your /var/log/messages 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 (normally 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 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
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 charac
ter 'a'+target-id to the special device name. For exam
ple, the SCSI device connected to the first SCSI con
troller 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
E.g., a value of 128 requests all debug output to
be printed. Smaller levels reduce verbosity.
SEE ALSO
sane(7), sane-find-scanner(1), sane-"backendname"(5)
AUTHOR
David Mosberger
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