User's Manual

DLT4000 SCSI Interface
8-122 DLT4000/DLT4500/DLT4700 Cartridge Tape Subsystem
8.4.23 TEST UNIT READY (00h)
Bit
7 6 5 4 3 2 1 0
0 Operation Code (00h)
1 Logical Unit Number Reserved
2 Reserved
Byte 3 Reserved
4 Reserved
5 Unused Reserved Flag Link
Figure 8-77 TEST UNIT READY CDB
TEST UNIT READY checks if the drive unit is ready for commands involving tape
movement. If the drive has a tape loaded, the command returns a GOOD status.
Otherwise, CHECK CONDITION is reported.
It is possible to get multiple check conditions on a TEST UNIT READY command
because of power cycle, code update, and tape loaded.
8.4.23.1 Medium Changer Considerations
When directed at the Media Loader LUN, this command will return Check Condition,
Sense Key, or Not Ready if:
• The Mode Select key switch is in the Service mode, and there is no 24V signal
(usually means the loader assembly has been moved out of its sleeve enough to
trip the 24V interlock.)