
16-2
SCSI REFERENCE 1014826
CHAPTER 16—RECEIVE DIAGNOSTIC RESULTS (1Ch)
16.2 WHAT YOU SEND TO THE LIBRARY
Bytes 03 and 04 – Allocation Length
This field specifies the number of bytes that the initiator has allocated for the
return of RECEIVE DIAGNOSTICS RESULTS data. The library returns only
one diagnostic page per command.
Table 16-1 lists the diagnostic pages returned by the RECEIVE DIAGNOSTIC
command and their maximum page lengths. Setting the Allocation Length to 0
indicates that no diagnostic data will be returned and is not an error.
The library terminates the Data In phase when the number of bytes specified
in the Allocation Length field has been transferred or when all available data
has been transferred to the initiator, whichever is less.
16.3 WHAT THE LIBRARY RETURNS
When the library receives a RECEIVE DIAGNOSTIC RESULTS command, it
returns the results of the previous SEND DIAGNOSTIC command. Each page
of the diagnostic data begins with a four-byte Diagnostic Parameter Header
(bytes 00 through 03), followed by the diagnostic parameters for that page.
The Diagnostic Parameter Header indicates the page code for the diagnostic
parameter data being returned and indicates the total length of the data to
follow.
Byte 00 – Page Code
This field identifies the page code of the diagnostic for which the tape drive is
returning data. Table 16-1 lists the valid page codes.
Table 16-1 Maximum page length of each supported RECEIVE DIAGNOSTIC page
Page Code Page Name Maximum Length
a
a
This maximum length value includes the four-byte Diagnostic Parameter header sent with each page.
00h Supported Diagnostic Pages page 20h (32 bytes)
F0h Self Test page 400h (1,024 bytes)
FFh No Diagnostic Results Available page 04h (4 bytes)
Bit
Byte
7 6 5 4 3 2 1 0
00 Page Code
01 Reserved
02 (MSB)
Page Length
(LSB)
03
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