Filter
Top Products
4-52
4.6.2 Message types
Messages provide information consisting of one or more bytes that are transferred in the MESSAGE IN and
MESSAGE OUT phases. These messages are used to control the bus phase sequence.
The initiator creates an ATTENIION condition for the target, indicating that it has a message to be reported
to the target Only then the target switches to the MESSAGE OUT phase to receive the message.
If the target has completed the SELECTION phase, it can execute the MESSAGE IN phase at any time to
send the message to the initiator.
The messages that can be communicated with this scanner are listed on the following table.
Table 4-24
Code Message
00 COMMAND COMPLETE
05 INIATIATOR DETECTED
ERROR
06 ABORT
07 MESSAGE REIECF
08 NO OPERATION
09 MESSAGE PARITY ERROR
0C BUS DEVICE RESET
8O TO FF IDENTIFY
4.6.2.1 COMMAND COMPLETE (X'00'): MESSAGE IN phase (target → initiator)
This message indicates that a command has been terminated and a valid status has been reported to the
initiator.
The target always reports the COMMAND COMPLETE message after the STATUS phase at the
completion the input/output operation. (This requirement also applies if the COMMAND phase is not
executed because command cannot be received.)
Upon receiving the COMMAND COMPLETE message, the initiator knows that a command has
terminated.
After sending the COMMAND COMPLETE message, the target switches into the BUS FREE phase.
If the COMMAND COMPLETE message is rejected with the MESSAGE REJECT message, this scanner
switches into the BUS FREE phase.
4.6.2.2 INITIATOR DETECTED ERROR (X'05'): MESSAGE OUT phase (initiator → target)
This message indicates that the initiator detected a retriable error and intends to request the target for retry.