Bidi Direction; Table 1.27 Bidi Direction - Fujitsu MAW3073 SERIES Specifications

The LOGICAL UNIT NUMBER field specifies the address of the logical unit of the I_T_L_Q
nexus for the current task. The structure of the logical unit number field shall be as defined in the
SCSI Architecture Model-2 standard. If the addressed logical unit does not exist, the task manager
shall follow the SCSI rules for selection of invalid logical units as defined in the SCSI Primary
Commands-3 standard.
The DATA LENGTH field contains the length in bytes of the following information units. For SPI
data stream information units the data length field contains the length in bytes of each SPI data
stream information unit that follows (i.e., the total number of bytes transferred would equal the
data length times the number of SPI data stream information units transferred). The data length
shall not include any of the 4 byte iuCRC nor any transmitted pad bytes (e.g., a data length of 509
with a iuCRC interval of zero or greater than 509 would transfer 509 bytes of data plus 3 bytes of
pad plus 4 bytes of iuCRC for a total transfer of 516 bytes). The TARG will not set the data length
to a value that exceeds the maximum burst size as defined in the disconnect-reconnect page.
The BIDI DIRECTION field determines the data direction if the command is a bidirectional
command and the type code is data or data stream. The code values for the BIDI DIRECTION
field are defined in table 1.27.
Codes Description
00b A unidirectional command or a type code other than data or data stream.
(see table 1.26)
01b A bidirectional command transferring data from the SCSI initiator device to the SCSI
target device.
10b A bidirectional command transferring data from the SCSI target device to the SCSI
initiator device.
11b Reserved.
The IUCRC INTERVAL field contains the length in bytes of the data to be sent before a iuCRC is
transferred. The iuCRC interval length shall not include the 4 byte iuCRC nor any transmitted pad
bytes (e.g., an iuCRC interval length of 510 transfer 510 bytes of data plus 2 bytes of pad plus 4
bytes of iuCRC for a total transfer of 516 bytes). The iuCRC interval shall be a multiple of two
(i.e., odd numbers are not allowed). If the iuCRC interval is equal to zero or is greater than or
equal to the data length only one iuCRC shall occur at the end of the SPI information unit.
1-118
Table 1.27

BIDI DIRECTION

C141-C011