sane-scsi(5) SANE Scanner Access Now Easy sane-scsi(5)NAMEsane-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 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 identify scanners by the SCSI ven-
dor 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 remain-
ing 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 match-
ing 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 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/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 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.
LINUX INFO
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
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 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). 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 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". Some peo-
ple reported that their scanner 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 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 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 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
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 ver-
bosity.
SANE_SCSICMD_TIMEOUT
sets the timeout value for SCSI commands in sec-
onds. Overriding the default value of 120 seconds
should only be necessary for very slow scanners.
SEE ALSOsane(7), sane-find-scanner(1), sane-"backendname"(5),
sane-usb(5)AUTHOR
David Mosberger
sane-backends 1.0.12 07 Dec 2002 sane-scsi(5)
