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4.7 Command Sequence
This section describes the initial sequence and read sequence.
4.7.1 Initial sequence
Host side Scanner side
Power ON/reset/initialize
Scanner does not respond for 3 sec
Verify the logical unit INQUIRY Prepare INQUIRY data
Respond with INQUIRY data
INQUIRY data
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Verify scanner READY TEST UNIT READY Respond with GOOD status
if READY
Status byte Respond with CHECK
Check status byte CONDITION status if
Receive GOOD status UNIT ATTENTION
Receive CHECK CONDITION
status REQUEST SENSE Prepare sense data
Request sense data Sense data Respond with sense data
Receive UNIT ATTENTION Clear sense data (Release
sense data UNIT ATTENTION)
....................................................................................................................................................................................
Verify scanner READY TEST UNIT READY Respond with GOOD status
if READY
Check status byte Status byte Respond with CHECK
Receive GOOD status CONDITION status if
Receive CHECK CONDITION NOT READY
status
Prepare sense data
Request sense data REQUEST SENSE Respond with sense data
Receive sense data
NOT READY Sense data
HARDWARE ERROR
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End (Ready to read) End (Ready to read)
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Abnormal termination