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ATAPI Interface Chapter 5
Seagate Travan 40 Product Manual Page 73
REQUEST SENSE (Group 0, Op. Code 03)
Information pertinent to the completion of a command is obtained by the REQUEST
SENSE command. Although a REQUEST SENSE command may be issued at any
time, it is typically issued immediately following a command that has resulted in a
Check Condition (Status 02h). Sense Data remains valid until reset by a subsequent
command issued by the same Initiator selecting the same LUN as the one that
resulted in the Check Condition. In the case of the single Initiator option, the drive will
assume that the REQUEST SENSE command is from the same Initiator. A
REQUEST SENSE command also resets the Sense Data and Sense information
(byte 0 to 11h). All other sense information is preserves, or in the case of Data Error
and Under-run Counters, updates may occur.
CDB for REQUEST SENSE Command
Data Bits
Byte 7 6 5 4 3 2 1 0 Hex
0 0 0 0 0 0 0 1 1 03
1 0 0 0 0 0 0 0 0 00
2 0 0 0 0 0 0 0 0 00
3 0 0 0 0 0 0 0 0 00
4 Transfer Length XX
5 0 0 0 0 0 0 0 0 00
The REQUEST SENSE command returns a Check Condition status only upon a
catastrophic failure in reporting the Sense Data. For example, a 1 bit in a reserved
field of the CDB or repeated bus parity errors. Under these conditions it is likely that
the Sense Data returned is not valid.
Transfer Length: Specifies the number of sense bytes requested by the Host. The
command terminates when either the number of bytes requested or all available
bytes are transferred whichever is less.
The following figure represents the Sense Byte Format.
Sense Data Format (for all Sense Keys except 0Ah—Copy Aborted)
Data Bits
Byte 7 6 5 4 3 2 1 0 Hex
00 AVF Error Code (70h or 71h) XX
01 0 0 0 0 0 0 0 0 00
02 FM EOM ILI 0 Sense Key XX
03
–
06
MSB
Sense Information
LSB
XX
XX
XX
07 Additional Sense Length (56 bytes) 38
08
–
0B
MSB
Command Specific Information
LSB
XX
XX
XX
0C Additional Sense Code XX
0D Additional Sense Code Qualifier XX
0E Field Replaceable Unit Code XX
0F SKSV C/D 0 0 BPV Bit Pointer XX
10
MSB
XX