SCSI Start Stop Unit Command
The SCSI Start/Stop Unit command is used to control the motor in a rotary device such as a SCSI disk-drive. It is also used to load or eject exchangeable media such as a tapes or CDs. It is a frequently-used command and is often the first one issued after initial communication has been established between the initiator and the target.
The CDB structure is:
bit→ |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
0 |
|---|---|---|---|---|---|---|---|---|
0 |
Operation code = 1Bh |
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1 |
LUN |
Reserved |
Immed |
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2 |
Reserved |
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3 |
Reserved |
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4 |
Reserved |
LoEj |
Start |
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5 |
Control |
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The parameter fields in the CDB have the following meaning:
- Immed - immediate - if this is one then the target will not wait until the operation has completed before sending back the status code.
- LoEj (load/eject) and Start - these two bits are used together:
- 00 - Stop motor
- 01 - Start motor
- 10 - Eject media
- 11 - Load media