14. Scanner Devices
14.1. Model for Scanner Devices
Scanner devices generate a digital representation of two or three
dimensional objects (e.g., a page of text, a photograph, or a piece of art).
This is accomplished by sensing the amount of light reflected from the object
and generating the digital data. The digital data can then be sent across the
SCSI bus to an initiator for further processing.
There are two types of scanners in use; in one type, the operations and
functions of the scanner are fixed; in the other type, the operations and
functions are programmable and need to be set up prior to being used for
scanning objects.
The scanner device generates the data and transfers it in accordance with
the commands received from the initiator. The contents of the data is vendor
specific, therefore the initiator and the scanner must know how to use the
contents of the data.
Scanners generate a digital image of an object in a two dimensional plane.
The x-axis dimension is along the cross-scan direction which is perpendicular
to the direction in which a scan occurs. The y-axis dimension is along the
scan direction and is parallel to the direction in which a scan occurs. The
coordinates are measured from the upper left hand corner of the two
dimensional plane. The x-axis measurement increases in a positive manner
going from left to right. The left side of the the two dimensional plane
(i.e., where x equals zero) is called the base element line. The y-axis
measurement increases in a positive manner going from top to bottom. The top
side of the two dimensional plane (i.e. where y equals zero) is called the
base line. The scanning range encompasses the area in which the scanner can
operate. It is the area from the scan line and base line to the maximum x and
y position. These conventions are adopted to aid in understanding the fields
within the command descriptor blocks and parameters used for scanner devices.
As such this is a conceptual model and may not accurately reflect the physical
device.
The displacements used for positioning windows is independent of the
resolution with which a window is scanned. The measurement of displacements
is controlled by the scan measurement mode parameters.
In the event of a scanner automatic creation of sub-windows within a defined
window (i.e., the auto bit in the DEFINE WINDOW parameters is one), one of the
following responses is appropriate:
1) the initiator may issue a GET WINDOW PARAMETERS command prior to any
READ commands
2) if the initiator issues a READ command before issuing a GET WINDOW
PARAMETERS command, the target shall return CHECK CONDITION status. The ILI
and valid bits in the sense data shall be set to one. The initiator should
then issue a GET WINDOW PARAMETERS command. This feature is useful when the
scanner has the ability to distinguish between image and text data and to
define windows accordingly.
It may occur that a scanner device temporarily does not have resources
available to manage a data transfer from the initiator or does not have data
available to transfer to the initiator. One of the following responses is
appropriate in such a case:
1) A CHECK CONDITION status is returned and the sense key is set to NOT
READY with the appropriate additional sense code. This is response is
applicable to a TEST UNIT READY command.
2) The target disconnects until the resource or data is available, and then
re-connects to resume the operation.
3) A BUSY status is returned.
If the scanner device determines that an error or exception condition has
occurred while executing the SCSI command from the initiator, a CHECK
CONDITION status is returned. A REQUEST SENSE command can then be used to
determine additional information regarding the error or exception condition.
14.2. Commands for Scanner Devices
The commands for scanner devices shall be as shown in Table 14-1.
Table 14-1: Commands for Scanner Devices
==============================================================================
Operation
Command Name Code Type Section Page
------------------------------------------------------------------------------
CHANGE DEFINITION 40h O 7.2.1
COMPARE 39h O 7.2.2
COPY 18h O 7.2.3
COPY AND VERIFY 3Ah O 7.2.4
GET DATA BUFFER STATUS 34h O 14.2.1
GET WINDOW 25h O 14.2.2
INQUIRY 12h M 7.2.5
LOG SELECT 4Ch O 7.2.6
LOG SENSE 4Dh O 7.2.7
MODE SELECT(6) 15h O 7.2.8
MODE SELECT(10) 55h O 7.2.9
MODE SENSE(6) 1Ah O 7.2.10
MODE SENSE(10) 5Ah O 7.2.11
OBJECT POSITION 31h O 14.2.3
READ 28h M 14.2.4
READ BUFFER 3Ch O 7.2.12
RECEIVE DIAGNOSTIC RESULTS 1Ch O 7.2.13
RELEASE UNIT 17h M 9.2.9
REQUEST SENSE 03h M 7.2.14
RESERVE UNIT 16h M 9.2.10
SCAN 1Bh O 14.2.5
SET WINDOW 24h M 14.2.6
SEND 2Ah O 14.2.7
SEND DIAGNOSTIC 1Dh M 7.2.15
TEST UNIT READY 00h M 7.2.16
WRITE BUFFER 3Bh O 7.2.17
==============================================================================
Key: M = Command implementation is mandatory.
O = Command implementation is optional.
All other operation codes for scanner devices are reserved for future
standardization.
14.2.1. GET DATA BUFFER STATUS Command
Table 14-2: GET DATA BUFFER STATUS Command
==============================================================================
Bit| 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
Byte | | | | | | | | |
==============================================================================
0 | Operation Code (34h) |
-----|-----------------------------------------------------------------------|
1 | Logical Unit Number | Reserved | Wait |
-----|-----------------------------------------------------------------------|
2 | Reserved |
-----|-----------------------------------------------------------------------|
3 | Reserved |
-----|-----------------------------------------------------------------------|
4 | Reserved |
-----|-----------------------------------------------------------------------|
5 | Reserved |
-----|-----------------------------------------------------------------------|
6 | Reserved |
-----|-----------------------------------------------------------------------|
7 | (MSB) |
-----|--- Allocation Length ---|
8 | (LSB) |
-----|-----------------------------------------------------------------------|
9 | Control |
==============================================================================
The GET DATA BUFFER STATUS command (Table 14-2) provides a means for the
initiator to get information about the data buffer. Information is returned
only for window identifiers for which a SCAN command has been received (see
14.1.9).
A wait bit of zero indicates that the target shall respond immediately. A
wait bit of one indicates that the target shall wait for image data to be
available before returning scan status data.
The data buffer status data format is defined in Table 14-3.
Table 14-3: Data Buffer Status Format
==============================================================================
Bit| 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
Byte | | | | | | | | |
==============================================================================
0 | (MSB) |
-----|--- ---|
1 | Data Buffer Status Length |
-----|--- ---|
2 | (LSB) |
-----|-----------------------------------------------------------------------|
3 | Reserved | Block |
==============================================================================
| Data Buffer Status Descriptor(s) |
==============================================================================
0 | Window Identifier |
-----|-----------------------------------------------------------------------|
1 | Reserved |
-----|-----------------------------------------------------------------------|
2 | (MSB) |
-----|--- ---|
3 | Available Data Buffer |
-----|--- ---|
4 | (LSB) |
-----|-----------------------------------------------------------------------|
5 | (MSB) |
-----|--- ---|
6 | Filled Data Buffer |
-----|--- ---|
7 | (LSB) |
==============================================================================
The data buffer status length indicates the length in bytes of the following
scan status data that is available to be transferred during the DATA IN phase.
The data buffer status length does not include itself. The data buffer status
data transferred to the initiator includes zero or more data buffer status
descriptors. Each descriptor returns information for the window specified by
the window identifier.
The block bit specifies the buffering capabilities of the scanner. A block
bit of one indicates that the data buffer is full and all image data must be
transferred to the initiator before the scan operation resumes. A block bit
of zero indicates that data buffer is not full and scan operations can
continue with the available data buffer space.
The available data buffer field indicates in bytes, the amount of buffer
available for transfers from the initiator. This field is valid only in
scanners with the ability to accept data from an initiator for processing.
The filled data buffer field indicates the amount of image data in bytes
available for transfer to the initiator.
14.2.2. GET WINDOW Command
Table 14-4: GET WINDOW Command
==============================================================================
Bit| 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
Byte | | | | | | | | |
==============================================================================
0 | Operation Code (25h) |
-----|-----------------------------------------------------------------------|
1 | Logical Unit Number | Reserved | Single |
-----|-----------------------------------------------------------------------|
2 | Reserved |
-----|-----------------------------------------------------------------------|
3 | Reserved |
-----|-----------------------------------------------------------------------|
4 | Reserved |
-----|-----------------------------------------------------------------------|
5 | Window Identifier |
-----|-----------------------------------------------------------------------|
6 | (MSB) |
-----|--- ---|
7 | Transfer Length |
-----|--- ---|
8 | (LSB) |
-----|-----------------------------------------------------------------------|
9 | Control |
==============================================================================
The GET WINDOW command (Table 14-4) provides a means for the initiator to
get information about previously defined windows.
A single bit of one specifies that a single window descriptor be returned
for the specified window identifier. A single bit of zero specifies that
window descriptors be returned for all window identifiers that were defined by
a SET WINDOWS command or by the target if the automatic bit was set to one.
The get window data shall consist of a header followed by one or more window
descriptors (see Tables 14-5, 14-6, and 14-7). Each window descriptor
specifies the location, size and scanning method used for a window.
Table 14-5: Get Window Data Header
==============================================================================
Bit| 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
Byte | | | | | | | | |
==============================================================================
0 | (MSB) |
-----|--- Window Data Length ---|
1 | (LSB) |
-----|-----------------------------------------------------------------------|
2 | Reserved |
-----|-----------------------------------------------------------------------|
3 | Reserved |
-----|-----------------------------------------------------------------------|
4 | Reserved |
-----|-----------------------------------------------------------------------|
5 | Reserved |
-----|-----------------------------------------------------------------------|
6 | (MSB) |
-----|--- Window Descriptor Length ---|
7 | (LSB) |
==============================================================================
The window data length specifies the length in bytes of the following data
that is available to be transferred. The window data length does not include
itself. If the allocation length is not sufficient to return all the get
window data the window data length shall not be adjusted to reflect the
truncation data.
The window descriptor length specifies the length in bytes of a single
window descriptor. Each descriptor shall be of equal length. The first
forty-eight bytes are defined in this standard and the remaining bytes in each
descriptor are vendor specific.
Table 14-6: Window Descriptor Bytes (1-23)
==============================================================================
Bit| 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
Byte | | | | | | | | |
==============================================================================
0 | Window Identifier |
-----|-----------------------------------------------------------------------|
1 | Reserved | Auto |
-----|-----------------------------------------------------------------------|
2 | (MSB) |
-----|--- X-Axis Resolution ---|
3 | (LSB) |
-----|-+---------------------------------------------------------------------|
4 | (MSB) |
-----|--- Y-Axis Resolution ---|
5 | (LSB) |
-----|-----------------------------------------------------------------------|
6 | (MSB) |
- - -|- - - X-Axis Upper Left - - -|
9 | (LSB) |
-----|-----------------------------------------------------------------------|
10 | (MSB) |
- - -|- - - Y-Axis Upper Left - - -|
13 | (LSB) |
-----|-----------------------------------------------------------------------|
14 | (MSB) |
- - -|- - - Window Width - - -|
17 | (LSB) |
-----|-----------------------------------------------------------------------|
18 | (MSB) |
- - -|- - - Window Length - - -|
21 | (LSB) |
-----|-----------------------------------------------------------------------|
22 | Brightness |
-----|-----------------------------------------------------------------------|
23 | Threshold |
==============================================================================
Table 14-7: Window Descriptor Bytes (24 - 39)
==============================================================================
Bit| 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
Byte | | | | | | | | |
==============================================================================
24 | Contrast |
-----|-----------------------------------------------------------------------|
25 | Image Composition |
-----|-----------------------------------------------------------------------|
26 | Bits Per Pixel |
-----|-----------------------------------------------------------------------|
27 | (MSB) |
-----|-+- Halftone Pattern ---|
28 | (LSB) |
-----|-----------------------------------------------------------------------|
29 | RIF | Reserved | Padding Type |
-----|-----------------------------------------------------------------------|
30 | (MSB) |
-----|--- Bit Ordering ---|
31 | (LSB) |
-----|-+---------------------------------------------------------------------|
32 | Compression Type |
-----|-----------------------------------------------------------------------|
33 | Compression Argument |
-----|-----------------------------------------------------------------------|
34 to| |
- - -|- - - Reserved - - -|
39 | |
-----|-----------------------------------------------------------------------|
40 to| |
- - -|- - - Vendor Specific Parameter Byte(s) - - -|
n | |
==============================================================================
The window identifier specifies the window defined by the window descriptor.
A window is referenced by the window identifier during data transfers and
parameter updates.
When used with the SET WINDOW command, an automatic (auto) bit of one
indicates that the target is allowed to create sub-windows within the window
specified. An auto bit of zero indicates that target is not allowed to create
sub-windows.
When used with the GET WINDOW command, an auto bit of zero indicates that
the window was defined directly by the SET WINDOW command. A value of one
indicates that the window was defined by the target. This is a sub-window
within a window defined by a SET WINDOW command.
The window identifiers assigned by the target shall be unique and not
currently in use. The parameters for the sub-windows may be retrieved using
the GET WINDOW command.
The x-axis resolution field specifies the resolution in the scan line
direction. The unit of measure is picture elements (pixels) per inch. A
value of zero specifies the default resolution.
The y-axis resolution field specifies the resolution in the base line
direction. The unit of measure is scan lines per inch. A value of zero
specifies the default resolution.
The x-axis upper left field specifies the x-axis coordinate of the upper
left corner of the window. This coordinate is measured from the scan line
using the target's current measurement unit divisor (see 14.3.3.1).
The y-axis upper left field specifies the y-axis coordinate of the upper
left corner of the window. This coordinate is measured from the base line
using target's current measurement unit divisor (see 14.3.3.1).
The window width field specifies the width of window in the scan line
direction. The window width is measured using the target's current
measurement unit divisor (see 14.3.3.1).
The window length field specifies the length of the window in the base line
direction. The window length is measured using the target's current
measurement unit divisor (see 14.3.3.1).
The brightness field specifies the level of brightness used to scan the
object. A value of zero specifies the default brightness or automatic
brightness control if it is supported. Any other value indicates a relative
brightness setting with 255 being the highest setting, one being the lowest
setting, and 128 being the nominal setting.
The threshold field specifies the threshold at which scan data is converted
to binary data. A value of zero specifies the the default threshold or
automatic threshold control if it is supported. Any other value indicates
relative threshold setting with 255 being the highest setting, one being the
lowest setting, and 128 being the nominal setting.
The contrast field specifies the level of contrast used to scan the object.
A value of zero specifies the default contrast or automatic contrast control
if it is supported. Any other value indicates a relative contrast setting
with 255 being the highest setting, one being the lowest setting, and 128
being the nominal setting.
The halftone field specifies the level of halftone at which the scan data is
converted to binary data. The values in this field are vendor specific. The
halftone field is used in conjunction with the image composition field.
The image composition field specifies the type of scan operation requested.
The image composition is defined as shown in Table 14-8.
Table 14-8: Image Composition Codes
==============================================================================
Code Description
------------------------------------------------------------------------------
00h Bi-level black & white
01h Dithered/halftone black & white
02h Multi-level black & white (gray scale)
03h Bi-level RGB Color
04h Dithered/halftone RGB Color
05h Multi-level RGB Color
06h - FFh Reserved
==============================================================================
The bits per pixel field specifies the number of bits used to represent the
intensity of a single color.
A reverse image format (RIF) bit of zero indicates that white pixels are to
be indicated by zeros and black pixels are to be indicated by ones. A RIF bit
of one indicates that white pixels are to be indicated by ones and black
pixels are to be indicated by zeros. The RIF bit is applicable only for
images represented by one bit per pixel.
The padding type field specifies how the target shall pad the image data
transmitted to the initiator if it is not an integral number of bytes. The
padding type is defined in Table 14-9.
Table 14-9: Padding Types
==============================================================================
Code Description
------------------------------------------------------------------------------
00h No padding
01h Pad with 0's to byte boundary
02h Pad with 1's to byte boundary
03h Truncate to byte boundary
04h - 07h Reserved
==============================================================================
The bit ordering field specifies the order in which data is transferred to
the host from the window. The bit ordering specifies the direction of pixels
in a scan line, the direction of scan lines within a window and the image data
packing within a byte. The values in this field are vendor specific.
The compression type and compression argument fields specify the compression
technique to be applied to the image data (see Table 14-10).
Table 14-10: Compression Types and Arguments
==============================================================================
Compression Description Compression
Code Argument
------------------------------------------------------------------------------
00h No compression Reserved
01h CCITT Group III, 1 dimensional Reserved
02h CCITT Group III, 2 dimensional K factor
03h CCITT Group IV, 2 dimensional Reserved
04h - 0Fh Reserved Reserved
10h Optical Character Recognition (OCR) Vendor Specific
11h - 7Fh Reserved Reserved
80h - FFh Vendor Specific Vendor Specific
==============================================================================
14.2.3. OBJECT POSITION Command
Table 14-11: OBJECT POSITION Command
==============================================================================
Bit| 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
Byte | | | | | | | | |
==============================================================================
0 | Operation Code (31h) |
-----|-----------------------------------------------------------------------|
1 | Logical Unit Number | Reserved | Position Function |
-----|-----------------------------------------------------------------------|
2 | (MSB) |
-----|--- ---|
3 | Count |
-----|--- ---|
4 | (LSB) |
-----|-----------------------------------------------------------------------|
5 | Reserved |
-----|-----------------------------------------------------------------------|
6 | Reserved |
-----|-----------------------------------------------------------------------|
7 | Reserved |
-----|-----------------------------------------------------------------------|
8 | Reserved |
-----|-----------------------------------------------------------------------|
9 | Control |
==============================================================================
The OBJECT POSITION command (Table 14-11) provides positioning functions.
Absolute as well as relative positioning is provided. A target shall return
CHECK CONDITION status and set the sense key to ILLEGAL REQUEST if a
positioning function is requested that is not supported.
The position function field specifies the requested function (see Table 14-
12).
The count field is used with the position function to specify the
displacement of the object.
Table 14-12: Position Function
=======================================
Position Function Description
----------------- --------------------
000b Unload Object
001b Load Object
010b Absolute Positioning
011b Relative Positioning
100b Rotate Object
101b Reserved
110b Reserved
111b Reserved
=======================================
Unload Object. This position function specifies that the object shall be
positioned for removal. If upon receipt of this command there is no object
loaded, the target shall return a GOOD status. This condition shall not be
considered as an error. If the target is unable to unload the object (i.e.,
paper jam or misfeed condition), the target shall return CHECK CONDITION
status and set the sense key sense to MEDIUM ERROR.
Load object. This position function specifies that the object is to be loaded
and positioned to the base line. If upon receipt of this command there is a
object already loaded, the target shall returns GOOD status. This condition
shall not be considered as an error. If an object is not loaded and the
target is unable to load an object, the target shall return CHECK CONDITION
status and set the EOM bit to one and the sense key to MEDIUM ERROR.
Absolute Positioning. This position function specifies that the object is to
be positioned at a y-axis displacement from the base line. The y-axis
displacement is determined using the count field and the target's current
measurement unit divisor (see 14.3.3.1). A count field of zero positions the
object at the base line.
Any other value in the count field shall cause the target to position the
object that number of units in the scan line direction. If there is no object
loaded or if the specified y-axis displacement is not achieved the target
shall return CHECK CONDITION status and set the EOM bit to one and the sense
key to MEDIUM ERROR.
Relative Positioning. This position function specifies that the object is to
be positioned at a y-axis displacement relative to the current position. The
y-axis displacement is determined using the count field and the target's
current measurement unit divisor (see 14.3.3.1). A count field of zero causes
no change in position of the object.
A positive value in the count field shall cause the target to position the
object that number of units in the scan line direction. If the scan range is
exceeded the target shall return CHECK CONDITION status. The EOM bit is set
to one, the ILI bit is set to one, and sense key is set to MEDIUM ERROR. The
valid bit is set to one and the information bytes are set to the difference
(residue) between the requested count and the actual number of units moved.
A negative value (e.g., twos complement notation) in the count field shall
cause the target to position the object that number of units toward the base
line. If there is no object loaded or if the specified y-axis displacement is
not achieved the target shall return CHECK CONDITION status and set the EOM
bit to one and the sense key to MEDIUM ERROR. If the base line is encountered
the target shall position the object at the base line and return CHECK
CONDITION status. The ILI bit is set to one and the sense key is set to
MEDIUM ERROR. The valid bit is set to one and the information bytes are set
to the difference (residue) between the requested count and the actual number
of units moved.
Rotate object. This position function specifies that the object is to be
rotated in a counter-clockwise direction in units of one one-thousandth of a
degree. The count field specifies the number of units that the object is to
be moved.
14.2.4. READ Command
Table 14-13: READ Command
==============================================================================
Bit| 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
Byte | | | | | | | | |
==============================================================================
0 | Operation Code (28h) |
-----|-----------------------------------------------------------------------|
1 | Logical Unit Number | Reserved |
-----|-----------------------------------------------------------------------|
2 | Data Type Code |
-----|-----------------------------------------------------------------------|
3 | Reserved |
-----|-----------------------------------------------------------------------|
4 | (MSB) |
-----|--- Data Type Qualifier ---|
5 | (LSB) |
-----|-----------------------------------------------------------------------|
6 | (MSB) |
-----|--- ---|
7 | Transfer Length |
-----|--- ---|
8 | (LSB) |
-----|-----------------------------------------------------------------------|
9 | Control |
==============================================================================
The READ command (Table 14-13) requests that the target transfer data to the
initiator.
The transfer data type distinguishes between the different types of data
which may be transferred between the initiator and the target. The types of
transfers are specified in Table 14-14.
Table 14-14: Data Type Codes
==========================================================
Code Description
----------------------------------------------------------
00h Image
01h Vendor Specific
02h Halftone Mask
03h Gamma Function
04h - 7Fh Reserved
80h - FFh Vendor Specific
==========================================================
The data type qualifier field provides a means to differentiate data
transfers of the same data type code. The values used in this field are
vendor specific.
The transfer length specifies the number of blocks the target shall transfer
to the initiator during the DATA IN phase. The block size is the current
block size in the mode parameters block descriptor (see 7.3.3). A transfer
length of zero, is not considered an error and no data shall be transferred.
If the target transfers less than transfer length blocks a CHECK CONDITION
status shall be returned. The ILI bit is set to one, the valid bit is set to
one, and the information bytes are set to the difference (residue) between the
requested transfer length and the actual number of blocks transferred.
This command shall be terminated with a status of RESERVATION CONFLICT if
any reservation access conflict (see 9.2.10) exists and no data shall be
transferred.
14.2.5. SCAN Command
Table 14-15: SCAN Command
==============================================================================
Bit| 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
Byte | | | | | | | | |
==============================================================================
0 | Operation Code (1Bh) |
-----|-----------------------------------------------------------------------|
1 | Logical Unit Number | Reserved |
-----|-----------------------------------------------------------------------|
2 | Reserved |
-----|-----------------------------------------------------------------------|
3 | Reserved |
-----|-----------------------------------------------------------------------|
4 | Transfer Length |
-----|-----------------------------------------------------------------------|
5 | Control |
==============================================================================
The SCAN command (Table 14-15) requests the target begin a scan operation.
The transfer length specifies the length in bytes of the window identifier
list that shall be sent during the DATA OUT phase. A transfer length of zero
indicates that no data shall be transferred. This condition shall not be
considered as an error.
The window identifier list consists of zero or more window identifiers each
of which specifies a window to be scanned.
14.2.6. SEND Command
Table 14-16: SEND Command
==============================================================================
Bit| 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
Byte | | | | | | | | |
==============================================================================
0 | Operation Code (2Ah) |
-----|-----------------------------------------------------------------------|
1 | Logical Unit Number | Reserved |
-----|-----------------------------------------------------------------------|
2 | Data Type Code |
-----|-----------------------------------------------------------------------|
3 | Reserved |
-----|-----------------------------------------------------------------------|
4 | (MSB) |
-----|--- Data Type Qualifier ---|
5 | (LSB) |
-----|-----------------------------------------------------------------------|
6 | (MSB) |
-----|--- ---|
7 | Transfer Length |
-----|--- ---|
8 | (LSB) |
-----|-----------------------------------------------------------------------|
9 | Control |
==============================================================================
The SEND command (Table 14-16) transfers data from the initiator to the
target.
The data type code and data type qualifier are defined in the READ command
(see 14.2.5).
The transfer length specifies the number of blocks the target shall transfer
from the initiator during the DATA OUT phase. The block size is the current
block size in the mode parameters block descriptor (see 7.3.3). A transfer
length of zero, is not considered an error and no data shall be transferred.
This command shall be terminated with a status of RESERVATION CONFLICT if
any reservation access conflict (see 9.2.10) exists and no data shall be
transferred.
14.2.7. SET WINDOW Command
Table 14-17: SET WINDOW Command
==============================================================================
Bit| 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
Byte | | | | | | | | |
==============================================================================
0 | Operation Code (24H) |
-----|-----------------------------------------------------------------------|
1 | Logical Unit Number | Reserved |
-----|-----------------------------------------------------------------------|
2 | Reserved |
-----|-----------------------------------------------------------------------|
3 | Reserved |
-----|-----------------------------------------------------------------------|
4 | Reserved |
-----|-----------------------------------------------------------------------|
5 | Reserved |
-----|-----------------------------------------------------------------------|
6 | (MSB) |
-----|--- ---|
7 | Transfer Length |
-----|--- ---|
8 | (LSB) |
-----|-----------------------------------------------------------------------|
9 | Control |
==============================================================================
The SET WINDOW command (Table 14-17) provides a means for the initiator to
specify one or more windows within the scanning range of the device.
The transfer length specifies the length in bytes of the data that shall be
sent during the DATA OUT phase. A transfer length of zero indicates that no
window parameters data shall be transferred. This condition shall not be
considered as an error.
The window parameters data shall consist of a header followed by one or more
window descriptors (see Tables 14-18, 14-6, and 14-7). Each window descriptor
specifies the location, size and scanning method used for a window.
Table 14-18: Set Window Data Header
==============================================================================
Bit| 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
Byte | | | | | | | | |
==============================================================================
0 | Reserved |
-----|-----------------------------------------------------------------------|
1 | Reserved |
-----|-----------------------------------------------------------------------|
2 | Reserved |
-----|-----------------------------------------------------------------------|
3 | Reserved |
-----|-----------------------------------------------------------------------|
4 | Reserved |
-----|-----------------------------------------------------------------------|
5 | Reserved |
-----|-----------------------------------------------------------------------|
6 | (MSB) |
-----|--- Window Descriptor Length ---|
7 | (LSB) |
==============================================================================
The window descriptor length specifies the length in bytes of a single
window descriptor. Each descriptor shall be of equal length. The first
forty-eight bytes are defined in this standard and the remaining bytes in each
descriptor are vendor specific.
See Tables 14-6 and 14-7 for the definition of a window descriptor.
14.3. Parameters for Scanner Devices
14.3.1. Diagnostic Parameters
This section defines the descriptors and pages for diagnostic parameters
used with scanner devices.
The diagnostic page codes for scanner devices are defined in Table 14-19.
Table 14-19: Diagnostic Page Codes
==============================================================================
Page Code Description Section
------------------------------------------------------------------------------
00h Supported Diagnostic Pages 7.3.1.1
01h - 7Fh Reserved
80h - FFh Vendor-specific pages
==============================================================================
14.3.2. Log Parameters
This section defines the descriptors and pages for log parameters used with
scanner devices.
The log page codes for scanner devices are defined in Table 14-20.
Table 14-20: Log Page Codes
==============================================================================
Page Code Description Section
------------------------------------------------------------------------------
01h Buffer Over-Run/Under-Run Page 7.3.2.1
03h Error Counter Page (Read) Page 7.3.2.2
07h Last n Error Events Page 7.3.2.3
06h Non-Medium Error Page 7.3.2.4
00h Supported Log Pages 7.3.2.5
08h - 2Fh Reserved
3Fh Reserved
30h - 3Eh Vendor-specific pages
==============================================================================
14.3.3. Mode Parameters
This section defines the descriptors and pages for mode parameters used with
scanner devices.
The mode parameter list, including the mode parameter header and mode block
descriptor is defined in 7.3.3.
The medium-type code field is contained in the mode parameter header (see
Tables 7-61 and 7-62). This field is reserved for scanners devices.
The device specific parameter field is contained in the mode parameter
header (see Tables 7-61 and 7-62). This field is reserved for scanners
devices.
The density code field is contained in the mode parameter block descriptor
(see Table 7-63). This field is reserved for scanners devices.
The mode page codes for scanner devices are defined in Table 14-21.
Table 14-21: Mode Page Codes
==============================================================================
Page Code Description Section
------------------------------------------------------------------------------
0Ah Control Mode Page 7.3.3.1
02h Disconnect-Reconnect Page 7.3.3.2
03h Measurement Units Page 14.3.3.1
09h Peripheral Device Page 7.3.3.3
01h Reserved
03h - 08h Reserved
0Bh - 1Fh Reserved
3Fh Returns all pages (valid only for the MODE SENSE command)
20h - 3Eh Vendor-specific pages (page format required)
00h Vendor Specific (does not require page format)
==============================================================================
14.3.3.1. Measurement Units Page
Table 14-22: Measurement Units Page
==============================================================================
Bit| 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
Byte | | | | | | | | |
==============================================================================
0 | PS |Reserved| Page Code (03h) |
-----|-----------------------------------------------------------------------|
1 | Parameter Length (06h) |
-----|-----------------------------------------------------------------------|
2 | Basic Measurement Unit |
-----|-----------------------------------------------------------------------|
3 | Reserved |
-----|-----------------------------------------------------------------------|
4 | (MSB) |
-----|--- Measurement Unit Divisor ---|
5 | (LSB) |
-----|-----------------------------------------------------------------------|
6 | Reserved |
-----|-----------------------------------------------------------------------|
7 | Reserved |
==============================================================================
The measurement units page (Table 14-22) specifies the units of measurement
used for calculating the displacement of window and for positioning an object.
The measurement units are independent of the horizontal and vertical scan
resolutions.
The parameters savable (PS) bit is only used with the MODE SENSE command.
This bit is reserved for the MODE SELECT command. A PS bit of one indicates
that the target is capable of saving the page in a non-volatile vendor-
specific location.
The basic measurement unit field is defined in Table 14-23. Targets shall
use inches as the default basic measurement unit.
Table 14-23: Basic Measurement Units
==============================================================================
Code Description
--------- ----------------------------------------------------------------
00h Inch
01h Millimeter
02h Point
03h - FFh Reserved
==============================================================================
The measurement unit divisor specifies the number of units needed to equal
one basic measurement unit. Targets shall use 1200 as the default measurement
unit divisor. If a value of zero is specified the target shall return CHECK
CONDITION status and set the sense key to ILLEGAL REQUEST.
IMPLEMENTORS NOTE: A target which does not implement this page or only
supports default values uses one twelve-hundredths (1/1200) of an inch as
the unit of measure.
14.4. Glossary for Scanner Devices
base element line. A x-axis displacement equal to zero.
base line. A y-axis displacement equal to zero.
beginning-of-medium. A x-axis and y-axis of zero displacement. Alternatively
this is being positioned at the intersection of the base and scan lines.
end-of-medium. The maximum x-axis and y-axis displacement.
image. The digital result of a scan.
object. The original or item being scanned.
pixel. Picture-element, is the smallest photo sight in the array.
platen. The surface in which the target is positioned.
scan. An operation that generates a digital image from the reflected light of
an object.
scan line. A y-axis displacement from the base line.
scanning range. The total area that a scanner can generate an image from.
For two dimensional objects this may correspond to the largest object that can
be scanned.
window. All or part of the scanning range of a scanner. A window defines the
part of the object scanned.