4-19
(d) A bit and field described as "Reserved" are 0.
If this scanner receives a value other than 0, it returns an error as follows:
Status key: B'00001 '(CHECK CONDITON)
Sense key: X~5'(ILLEGAL REQUES~I)
The commands supported by this scanner are listed below.
Table 4-7
Commands
Command
Operation
code (hex)
Description
RESERVE UNIT
16
Declares the exclusive use of a logical unit
RELEASE UNIT
17
Cancels the declaration of the exclusive use of a logical unit
INQUIRY
12
Examines the information regarding the target and logical unit
REQUEST SENSE
03
Requests a target for sense data
SEND DIAGNOSTIC
ID
Requests a target for self-check
TEST UNIT READY
00
Checks whether or not a logical unit is ready
SET WINDOW
24
Sets a window
OBJECT POSITION
31
Controls the automatic document feeder
READ
28
Requests transfer of image data
SCAN
1B
Requests the target to begin a scan operation
4.4.1
RESERVE UNIT command
The following table shows the normal sequence of the RESERVE UNIT command when used with this scanner.
Table 4-8
RESERVE UNIT command
Step
Bus phase
Initiator operation
←
←→
→
Target operation
1
BUS FREE
Verifies bus free
2
ARBITRATION
Obtains bus-usage right
3
SELECTION
Selects target
→
Drives BSY signal
4
MESSAGE OUT
Selects logical unit
→
5
COMMAND
Specifies RESERVE UNIT (CDB)
→
6
STATUS
Reports GOOD status
7
MESSAGE IN
←
Reports message
(Command complete)
Releases ESY signal
8
BUS FREE