A.6 Messages
(10)SAVE DATA POINTER (X’02’) : MESSAGE IN phase (target → initiator)
This message is sent from the target to the initiator in order to save the current data pointer. The initiator saves the current data pointer value into the saved pointer for the logical unit currently connected.
When the disconnection is enabled by the IDENTIFY message and this scanner cannot prepare data to be transferred in the DATA IN phase, this scanner issues the DISCONNECT message after issuing the SAVE DATA POINTER message so that the SCSI bus is released.
Notes:
1.When no memory option is provided, this scanner does not issue the SAVE DATA POINTER message.
2.When the required data for the READ command is less than 64 KB, this scanner does not issue the SAVE DATA POINTER message.
(11)RESTORE POINTERS (X’03’) : MESSAGE IN phase (target → initiator)
The initiator restores the saved pointer by using this message. The initiator restores the command data status pointer value from the saved pointer for the logical unit connected when this message is received. The initiator stores the value into the current pointer.
Note:
This scanner issues the RESTORE POINTER message only during error recovery when the INITIATOR DETECTED ERROR message has been received.
(12)SYNCHRONOUS DATA TRANSFER REQUEST (Extended message) Message IN/OUT Phase (Init ↔ Targ)
The SYNCHRONOUS DATA TRANSFER REQUEST consists of 5bytes is only an extended message by this scanner.
SYNCHRONOUS DATA TRANSFER REQUEST
Bit | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
Byte
0Extended message (06h)
1Extended message length (03h)
2SYNCHRONOUS DATA TRANSFER REQUEST code (01h)
3Transfer Period Factor
4REQ/ACK Offset
Appendix