M2488 PRODUCT GUIDE TAPE UNIT SCSI COMMANDS
April 1997 CG00000-011503 REV. A 4-117
4-3.27 SEND DIAGNO STIC comman d 1Dh
The SEND DIAGNOSTIC command requests the target to perform diagnostic tests on itself, or on
the attached peripheral devices. After the receipt of a valid SEND DIAGNOSTIC command, the unit
performs synchronization prior to execution of the SEND DIAGNOSTIC operation. Disconnection
occurs, if allowed, during the execution of the function. When the Selftest bit is zero, this command
is usually followed by a RECEIVE DIAGNOSTIC RESULTS command.
4-3.27.1 SEND DIAGNOSTIC CDB Description
SEND DIAGNOSTIC is a six-byte command. The bytes are shown below and described in
Table 4-107. Common fields are described in paragraph 4-3.1 on page 4-4.
The following Field Description table specifies the use of each field of the SEND DIAGNOSTIC
CDB. Refer t o Table 4-108 in conjunction with the following table for a more concise overview of
how each field is used.
BITS
BYTES 7 6 5 4 3 2 1 0
00 0 0 1 1 1 0 1
1LUN PF Reserved Selftest DevOfL UnitOfL
2Reserved
3MSB Parameter List Length
4LSB
5Reserved Flag Link
Note: Changeable fields in the CDB are shaded.
Table 4-107. SEND DIAGNOSTIC Field Description
BYTE BIT VALUE DESCRIPTION
0 0-7 1Dh Operation code.
1 0 1 A UnitOfL (Unit Offline) bit of 1 enables write operations on user medium or opera-
tions that affect user visible medium positioning.
1 1 1 A DevOfL (Device Offline) bit of 1 enables diagnostic operations that may adversely
affect operations to other logical units on the same target.
1 2 1
0A Selftest bit of 1 directs the target to complete its default selftest.
A Selftest bit of 0 directs the target to perform tests defined by the bytes in the
parameter list. Successful completion of the function and preparation of a response is
indicated by presentation of GOOD status. The response is then recovered by execu-
tion of the RECEIVE DIAGNOSTIC RESULTS command.