Fujitsu 600C manual RELEASE UNIT command COMMAND phase initiator → target

Models: 600C

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4.4.2RELEASE UNIT command

4.4.2RELEASE UNIT command

The following table shows the normal sequence of the RESERVE UNIT command when used with this scanner.

Table 4-9RELEASE UNIT command

Step

Bus phase

Initiator operation

←→

Target operation

 

 

 

 

 

1

BUS FREE

Verifies bus free

 

 

 

 

 

 

 

2

ARBITRATION

Obtains bus-usage right

 

 

 

 

 

 

 

3

SELECTION

Selects target

 

 

 

 

 

 

 

 

 

 

Drives BSY signal

 

 

 

 

 

4

MESSAGE

Selects local unit

 

 

OUT

 

 

 

 

 

 

 

 

5

COMMAND

Specifies RELEASE

 

 

 

UNIT (CDB)

 

 

 

 

 

 

 

6

STATUS

 

Reports GOOD status

 

 

 

 

 

7

MESSAGE IN

 

Reports message (Command Complete)

 

 

 

 

 

 

 

 

 

Releases BSY signal

 

 

 

 

 

8

BUSFREE

 

 

 

 

 

 

 

 

4.4.2.1RELEASE UNIT command: COMMAND phase (initiator target)

The RELEASE UNIT command releases a reserved status. If this command comes from an initiator that has not declared reservation, the target ignores the command and responds with the GOOD status (the reserved status is not released).

The CDB of this command is shown in the following illustration.

Byte 0

1

2

3

4

5

7

6

5

4

3

2

1

0

 

 

 

Operation code X'17'

 

 

 

 

 

 

 

 

 

 

 

Logical unit number

TP

 

TPID

 

(Reserved)

 

 

 

 

 

 

 

 

(Reserved)

Control byte

(a) TP (third party): Byte 1

4-21

Page 49
Image 49
Fujitsu 600C manual RELEASE UNIT command COMMAND phase initiator → target