User's Guide

Page 114 DDS-4 SCSI Interface Manual, Rev. B
READ ELEMENT STATUS (Autoloader Only) (B8h)
The READ ELEMENT STATUS command requests the Autoloader to report the
status of its elements to the host. The status of ALL element types are reported.
READ ELEMENT STATUS Command Descriptor Block
The following table shows the layout of the CDB.
Byte
Bits
7 6 5 4 3 2 1 0
0 1 0 1 1 1 0 0 0
1 LUN 0 0 Element Type Code
2 0 0 0 0 0 0 0 0
3 Starting Element Address
4 MSB—Number of Elements
5 Number of Elements—LSB
6 0 0 0 0 0 0 0 0
7 MSB—Allocation Length
8 Allocation Length
9 Allocation Length—LSB
10 0 0 0 0 0 0 0 0
11 vendor unique* 0 0 0 0 Flag Link
* This vendor-unique field is reserved and must be set to zero.
The starting element address specifies the minimum element address to report.
Only element addresses greater than or equal to the starting element address are
reported. If the starting element address is undefined, an Illegal Request Check
Condition is generated.
The number of elements specifies the maximum number of element descriptors to
be reported by the target for this command. If the Allocation Length is not sufficient
to transfer all of the requested element descriptors, the Autoloader transfers all the
descriptors that can be completely transferred. This situation is not considered an
error.
Element Status Data
The data returned by the READ ELEMENT STATUS command consists of an 8-byte
header, followed by one or three element status pages. Within each status page are
the appropriate element descriptors. The Element type Code can be 0, 1, 2, or 4.