Scanner Interface
The following table shows the normal sequence of the TEST UNIT READY command when used with this scanner.
Step | Bus phase | Initiator operation | ← → | Target operation |
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1 | BUS FREE | Verifies bus free |
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2 | ARBITRATION | Obtains |
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| right |
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3 | SELECTION | Selects target | → |
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| Drives BSY signal |
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4 | MESSAGE OUT | Selects logical unit | → |
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5 | COMMAND | Specifies TEST UNIT | → |
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| READY (CDB) |
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6 | STATUS |
| ← | Reports GOOD status |
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7 | MESSAGE IN |
| ← | Reports message (Command |
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| Complete) |
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| Releases BSY signal |
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8 | BUS FREE |
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(1)TEST UNIT READY command: COMMAND phase (initiator → target)
The TEST UNIT READY command checks whether a logical unit is ready. This command does not request
The CDB of this command is shown in the following illustration.
7 | 6 |
| 5 | 4 | 3 | 2 | 1 | 0 |
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Byte 0 |
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| Operation code X’00’ |
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1 |
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| Logical unit number |
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2 |
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3 |
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4 |
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5 |
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| Control byte |
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Appendix