Extended Message Format; Extended Message Codes - Fujitsu C150-E049-02EN Oem Manual

M3099GX/GH OEM Manual
A value of one in the first byte of a message indicates the beginning
of a multiple byte extended message. The minimum number of bytes
sent for an extended message is three. The extended message format
and the extended message code are shown in Table 3.84 and 3.85
respectively.
Table 3.84 Extended Message Format
Bit 7 6
Byte
0
1
2
3
n+1
The extended message length specifies the length in bytes of the
extended message code plus the extended message arguments to
follow. Therefore, the total length of the message is equal to the
extended message length plus two. A value of zero for extended
message length indicates 256 bytes follow.
The extended message codes are listed in Table 3.85 The extended
message arguments are specified within the extended message
descriptions.
Table 3.85 Extended Message Codes
Code(s) Description
02h Reserved (See Note)
00h MODIFY DATA POINTER
01h SYNCHRONOUS DATA TRANSFER REQUEST
03h WIDE DATA TRANSFER REQUEST
04h - 7Fh Reserved
80h - FFh Vendor Specific
Note: Extended message code 02h was used for the EXTENDED
IDENTIFY message in SCSI-1.
5 4 3
Extended message (01h)
Extended message length (n)
Extended message code (y)
Extended message arguments
INTERFACE
2 1 0
3-101