User's Guide

Page 54 DDS-4 SCSI Interface Manual, Rev. B
• If any page headers are received with unsupported page codes. (Table 4-30
lists the pages that can be set by the LOG SELECT command.)
• An incorrect log page length is specified in the page header.
• An illegal parameter code within a valid log page.
• Valid log pages are not sent in ascending order.
• Parameter codes of a supported page are not sent in ascending order.
The following table shows the log page header format.
Byte
Bits
7 6 5 4 3 2 1 0
0 0 0 Page Code
1 0 0 0 0 0 0 0 0
2 0 0 0 0 0 0 0 0
3 Page Length (n)
The Page Code field indicates which page is being sent to the drive.
The Page Length field indicates the length of log parameters (in bytes) that follow
the page header. If the LOG SELECT CDB parameter list length specified is too
small to transfer complete log parameters for the specified page, an Illegal Request,
Invalid Field in the CDB, is returned.
The following table shows a typical log parameter format.
Byte
Bits
7 6 5 4 3 2 1 0
0 MSB—Parameter Code
1 Parameter Code—LSB
2 DU 1 0 ETC TMC 0 0
3 Parameter Length (n-3)
4 Parameter Value
n Parameter Value
The Parameter Code field identifies which log parameter is being sent to the drive.
The parameter codes used for the page 2 (Write Error) and page 3 (Read Error) are
listed in subsequent tables.
All of the bits in byte 2 of the Log Parameter are collectively referred to as the
Parameter Control byte. The Parameter Control byte specifies counter controls.
The host specifies the Parameter Control byte to control
• Whether or not a counter is enabled.
• Whether or not a Check Condition is generated when a counter is incremented,
and if so, how the Check Condition is generated.
Each Log Parameter contains only one control byte. This control byte is shared
between the threshold and accumulated parameters. If a LOG SELECT command is