User's Guide

Page 152 DDS-4 SCSI Interface Manual, Rev. B
SEND DIAGNOSTIC (1Dh)
The SEND DIAGNOSTIC command requests the drive to perform diagnostic
operations on itself. The diagnostic tests are part of the drive firmware and are more
extensive than the power on self tests. Two tests are supported as defined in the
CDB with bits 2-0 of byte 2. The self test does not require media and will not change
any data on media in the drive. The Enhanced Diagnostic (read/write test) checks
the drive error rates during reading and requires a cartridge. All data on the inserted
cartridge is destroyed during this test. Users should allow up to two minutes for
these tests to complete.
Only a parameter list of zero is supported. A command with the Self-Test field set to
zero is not an error. In this case no diagnostic testing is performed.
Good status is returned if the test is successful. If any test fails the diagnostic is
terminated and check condition is returned. Additional information about the failed
test can be retrieved by the RECEIVE DIAGNOSTIC RESULTS command
SEND DIAGNOSTIC Command Descriptor Block
The following table shows the layout of the Command Descriptor Block.
Byte
Bits
7 6 5 4 3 2 1 0
0 0 0 0 1 1 1 0 1
1 0 0 0 0 0 Self-Test DEVOF Off-Line
2 0 0 0 0 0 0 0 0
3 0 0 0 0 0 0 0 0
4 0 0 0 0 0 0 0 0
5 vendor unique* 0 0 0 0 Flag Link
* This vendor-unique field is reserved and must be set to zero.
The combinations of bits in byte 1 are defined as shown in the following table.
Self-Test
Bit 2
DEVOF
Bit 1
Off-Line
Bit 0
Description
1 0 0 Self-test
1 1 1 Enhanced diagnostics (read/write test)