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 configura-
tion 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 gen-
eric 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 alter-
nate way allows 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
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), CHAN-
NEL 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 simplify configura-
tion, a field's value can be replaced with an asterisk sym-
bol (``*''). 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 com-
patible device. For example, the line
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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 permission
for the generic SCSI device is set appropriately. We recom-
mend to add a group "scanner" to /etc/group which contains
all users that should have access to the scanner. The per-
mission 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
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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 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 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 direc-
tory. 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 back-
end 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 probability 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.
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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 pro-
vides 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 run-
ning and the scanner is turned on, you can issue the com-
mand:
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.
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BusLogic BT958
To configure the BusLogic card, you may need to
follow these instructions (contributed by Jeremy
): 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 Con-
figuration''. 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.
(DTCT436/436P) ISA SCSI card
NCR/Symbios 53c400/53c400a or Domex DTC3181E/L/LE
This card is supplied by Mustek (and other ven-
dors). It's supported since Linux 2.2. The SCSI
cards are supported by the module g_NCR5380. It's
necessary to tell the kernel 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 documentation is
in this file and NCR5380.c.
NCR/Symbios 810
For some scanners it may be necessary to disable
disconnect/reconnect. To achieve this use the
option ncr53c8xx="disc:n". Some people 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 neces-
sary 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/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 (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.
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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 ter-
minate properly (it causes a SCSI timeout after 10
minutes). The generic AM53C974 also seems to work
fine and does not suffer from the timeout prob-
lems.
SOLARIS, OPENSTEP AND NEXTSTEP INFO
Under Solaris, OpenStep and NeXTStep, the generic SCSI dev-
ice 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), " .}S 3 1 "sane-backendname""
"(5)," "" "" "" "" sane-usb(5)
AUTHOR
David Mosberger
ATTRIBUTES
See attributes(5) for descriptions of the following
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attributes:
_________________________________________________________
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
|____________________|____________________________________|_
| Availability | image/scanner/xsane/sane-backends|
|____________________|____________________________________|_
| Interface Stability| Uncommitted |
|____________________|___________________________________|
NOTES
Source for SANE is available on http://opensolaris.org.
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