Specifications

ATAPI For Streaming Tape QIC-157 Rev B

6.8.6. LOG SENSE Command

The LOG SENSE command provides a means to retrieve statistical information maintained by the

Device about the Device. It is a complementary command to the LOG SELECT command.

Table 6-19 Log Sense Command

Bit

Byte

7 6 5 4 3 2 1 0

0 Operation code (4Dh)

1 Reserved Reserved

(PPC)

Reserved

(SP)

2 PC (01) Page Code

3 Reserved

4 Reserved

5 (MSB) Parameter Pointer

6 (LSB)

7 (MSB) Allocation Length

8 (LSB)

9 Reserved

10 Reserved

11 Reserved

The Page Control (PC) field defines the type of parameter values to be selected (see Table 6-17 Page

Control Field page 50). The parameter values returned by a LOG SENSE command are determined as

follows:

1. The specified parameter values at the last update (in response to a LOG SELECT or LOG SENSE

command or done automatically by the Device for cumulative values).

2. The default values if an update has not occurred since the last power-on, hard RESET condition,

or ATAPI Soft Reset.

The Page Code field identifies which page of data is being requested. If the Page Code is reserved or

not implemented, the Device shall terminate the command with “Check Condition” status. The Sense

Key shall be set to ILLEGAL REQUEST with the Additional Sense Code set to INVALID FIELD IN

COMMAND PACKET.

The Parameter Pointer field allows requested parameter data to begin from a specific parameter code

to the maximum Allocation Length or the maximum parameter code supported by the Device,

whichever is less. If the value of the Parameter Pointer field is larger than the largest available

parameter code that can be returned by the Device on the specified page, the Device shall terminate

the command with “Check Condition” status. The Sense Key shall be set to ILLEGAL REQUEST and

the Additional Sense Code shall be set to INVALID FIELD IN COMMAND PACKET.

Log parameters within the specified log page shall be transferred in ascending order according to

parameter code.