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4.6 Packet Commands
C156-E227-01EN 4-71
4.6.16 REQUEST SENSE command
Table 4.98 REQUEST SENSE command
Bit
Byte
76543210
0 Operation Code (03h)
1 Logical Unit Number Reserved
2-3 Reserved
4 Allocation Length
5-11 Reserved
The REQUEST SENSE command transfers sense data to the host. Sense data
indicates detailed error information on the command whose error was reported
previously. If no error command was reported, SENSE KEY indicates NO
SENSE.
When issuing the REQUEST SENSE command to detect the device status, first
issue the TEST UNIT READY command, then issue REQUEST SENSE.
Allocation Length indicates the length of sense data to be transferred in bytes. If
Allocation Length is 0, the command transfers no data and ends normally.
When the ODD detects a CRC error involving the Ultra DMA transfer during the
data transfer using this command, it returns the CHECK CONDITION. (The
Sense Key of the Error register indicates ABORTED COMMAND.)
The original sense data at the CRC error occurrence is reported normally using the
REQUEST SENSE command. Otherwise, it will be reported when another
command is received.
The sense data format is shown in Table 4.99.