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User’s Guide 21020285 D
Chapter 4 Command Operation
Some Example Single Commands Page 4 - 15
Example
2:Inquiry
Pass-through
Command
This example describes the issue of a Initiator Pass-through command. The
SCSI Inquiry command is fully described in the SCSI specification.
This example shows you how to use the Single Command structure to issue an
Initiator Pass-through command.
1. The set-up of a Pass-through command is the same as for a Board-
control command. You must select a portion of system memory for the
Single Command structure. You will need 52-bytes of space to hold the
Parameter Block, Interrupt and Reserved fields, and the Status Block
that make up a Single Command structure. For this example we’ll use
the same memory address.
Example Memory Address = 822F4H
2. Fill in the Parameter Block information. (Detailed Parameter Block
information for Initiator Pass-through commands is given in Chapter 5.
For information about the SCSI Inquiry command, you must reference a
SCSI specification or drive manual.)
These are the Parameter Block values for this example:
Command Identifier = 822F4H - Even though the Status Block is part of
the Single Command structure and easily identified it is good to provide a value
here in order to be consistent with Command List structures. The value chosen
is the address of the Single Command structure.
ID = 01H - Indicates to the RF3880 adapter that this Pass-through command
should be directed to device ID 1.
Address Modifier = 3DH - This value indicates Standard Supervisory Data
Access mode will be used to execute the Inquiry command.
Flags-1 = 0 - This byte is used to control aspects of command operation. None
of the features are enabled for this command.
Flags-2 = 0 - This byte offers further command control options. None of the
additional features are enabled for this example.
VME Memory Address = 99450H - System Memory address to which the
Inquiry data will be returned.
Transfer Count = 24H - This value is the number of bytes of data that will
be transferred for this command. The Inquiry data returned by this device is
contained in 36 (24H) bytes.
Address
Offset
Byte Memory Address
Offset + 0 Offset + 1 Offset + 2 Offset + 3
00H Command Indentifier = 000822F4H
04H Flags-2 = 0 Flags-1 = 0 Addr Mod = 3DH ID = 01H
08H VME Memory Address = 00099450H
0CH Transfer Count = 24H
10H Command = 12H LUN = 0 Reserved = 0 Reserved = 0 Inquiry
6-Byte
Command
Descriptor
Block
14H Allocation = 24H Flag/Link = 0 0 0
18H 0 0 0 0
Table 23: Example Pass-through command PB