Scanner Interface
Appendix A-22
A.4.1
RESERVE UNIT command
The following table shows the normal sequence of the RESERVE UNIT command when used with
this scanner.
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 BSY signal
8
BUS FREE
(1)
RESERVE UNIT command: COMMAND phase (initiator
→
target)
Where a logical unit can be accessed by two or more initiators, there could be interferences
with command sequences, data, etc. This situation can be avoided by issuing the RESERVE
UNIT command before initiating a series of operations.
Once a logical unit has properly accepted the RESERVE UNIT command, it will be occupied
by the initiator that issued the RESERVE UNIT command. If the 3rd party reservation
option is supported, the logical unit might be occupied by another SCSI unit - one having an
initiator function - which is specified TPID. In this condition, called “reserved,”, the logical
unit cannot be accessed from any other initiators. The reserved condition remains effective
until one of the following events take place:
1)
The reservation is replaced by a new RESERVE COMMAND from the same initiator
that has reserved the logical unit. (Issuing another RESERVE UNIT command with
the reservation still effective does not results in an error. The previously established
reservation is released as a result of 1), 2) or 3) described below.)
2)
The RELEASE UNIT command is issued from the same initiator that has reserved the
logical unit.
3)
The BUS DEVICE RESET message is sent from any initiator.
Summary of Contents for M3097DG
Page 1: ...C150 E103 01EN M3097DG Image Scanner OEM Manual ...
Page 2: ......
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Page 44: ...3 3 Optional image function 3 23 ...
Page 67: ...5 4 Consumable 5 13 Two rollers are included Figure 5 4 Pick roller ...
Page 70: ...6 3 Figure 6 1 Jam clearance ...