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4.4.11 READ command
The following table shows the normal sequence of the READ command when used
with this scanner.
Step Bus phase Initiator operation ¨ Æ Target operation
1 BUS FREE Verifies bus free
2 ARBITRATION Obtains bus>usage
right
3 SELECTION Selects target Æ
Drives BSY signal
4 MESSAGE OUT Selects logical unit Æ
5 COMMAND Specifies READ
(CDB)
Æ Reads document
6 DATA IN ¨ Transfers image data
7 STATUS ¨ Reports GOOD status
8 MESSAGE IN ¨ Reports message (Command
Complete)
Releases BSY signal
9 BUS FREE
(1) READ command: COMMAND phase (initiator Æ target)
The READ command is used by an initiator to request a target for transfer of data.
Upon receiving this command, the target returns scan data to the initiator.
The CDB of this command is shown in the following illustration.
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