M2488 PRODUCT GUIDE MEDIA CHANGE R COMMANDS
March 1997 CG00000-011503 REV. A 6- 11
6-2.3 MODE SENSE MC command 1Ah
The MODE SENSE medium-changer command provides a means for a target to report its medium
changer device parameters to the initiator. The MODE SENSE command is a complementary com-
mand to the MODE SELECT command. Please refer to the description of the MODE SELECT com-
mand for recommendation s on how to ensure that th e MODE SELECT command perf orms the
desired operations.
6-2.3.1 MODE SENSE CDB Description
MODE SENSE is a six-byte command. The bytes are shown below and described in the following
paragraphs. Common fields are described in paragraph 4-3.1 on page 4-4.
For both an ACL or an FACL, the target will perform the MODE SELECT command even if the
Medium Changer LUN is NOT READY.
BITS
BYTES 7 6 5 4 3 2 1 0
000011010
1LUN 0 DBD Reserved
2PC Page Code (see section 6-3 on page 6-32)
3Reserved
4Allocation Length
5Reserved Flag Link
Note: Changeable fields in the CDB are shaded.
Table 6-9. MODE SENSE Field Description
BYTE BIT VALUE DESCRIPTION
0 0-7 1Ah Operation code.
1 3 1
0
The Disable Block Descriptor (DBD) bit value of 1 specifies that no block descrip-
tor is returned in the MODE SENSE data.
Since the Medium Changer does not provide a block descriptor, the Block Descrip-
tor Length field in the MODE SENSE data read will always be set to zero indepen-
dent of the setting of the DBD bit in the MODE SENSE command.
2 0-5 The Page Code allows the initiator to select any specific page or all of the pages sup-
ported by a target. Pages are used to set and return device parameters. If the initiator
uses a Page Code value not implemented by the target, the target will return CHECK
CONDITION status with sense key set to ILLEGAL REQUEST, and additional
sense code to INVALID FIELD IN CDB.