Scanner Interface
The link will not be disconnected if bit 6 in the IDENTIFY message is 0. Also, it will not be disconnected if the IDENTIFY message is not issued in a given command sequence. For disconnect to occur therefore, bit 6 in the IDENTIFY message must be set to 1.
When performing the disconnection during data transfer, this scanner sends the SAVE DATA POINTER message before sending the DISCONNECT message so that the data pointer is saved.
Example:
BUS FREE
↓
ARBITRATION
↓
SELECTION
↓
MESSAGE OUT (IDENTIFY: BIT6=1)
↓
COMMAND (READ command)
↓
MESSAGE IN (DISCONNECT message)
↓
BUS FREE
. |
|
. | The data to be transferred to the initiator is prepared during this interval. |
. | |
. |
|
RESELECTION
↓
MESSAGE IN (IDENTIFY message)
↓
DATA IN (Transfer of image data)
↓
MESSAGE IN (SAVE DATA POINTER message)
↓
MESSAGE IN (DISCONNECT message)
↓
BUS FREE
.
. 
The data to be transferred to the initiator is prepared during this interval.
.
RESELECTION
↓
MESSAGE IN (IDENTIFY message)
↓
DATA IN (Transfer of image data)
↓
STATUS (GOOD status)
↓
MESSAGE IN (COMMAND COMPLETE message)
↓
BUS FREE
Appendix