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 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 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 simplify config-
uration, 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 regis-
tered 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 ven-
dor 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 equivalent to the one specified previ-
ously:
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 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 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 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 xcon-
fig'', this shows up under ''SCSI support->SCSI generic support''.
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 automati-
cally 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 allo-
cate 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 maxi-
mum 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 run-
ning 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 instruc-
tions (contributed by Jeremy <jeremy AT 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 config-
uration''. Change ''Negotiation'' to ''async'' and change ''Discon-
nect'' 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 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 perfor-
mance 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/recon-
nect. 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 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/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 character 'a'+target-id to the
special device name. For example, 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 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 1.0.18 28 Oct 2003 sane-scsi(5)
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