National Instruments GPIB-SCSI-A, Руководство пользователя

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Chapter 7 G Mode Functions
© National Instruments Corp. 7-113 GPIB-SCSI-A User Manual
write - Write
Type: SCSI function
Syntax:
write logical block address, transfer
length<CR>
or
write?<CR>
Purpose: Use
write
to command the GPIB-SCSI-A to process the
Group 0 SCSI WRITE command.
Remarks: The GPIB-SCSI-A uses the following Command Descriptor
Block to command the Target to process
write
. Notice how
the parameters to the
write
command are used in the
creation of the Command Descriptor Block.
Bit 7 6 5 4 3 2 1 0
Byte
0 0A
1 LUN Logical Block (Upper 5 bits)
2 Logical Block Address (Middle Significant Byte)
3 Logical Block Address (Least Significant Byte)
4 Transfer Length
5 VCB 00
The Logical Block Address and Transfer Length in the
Command Descriptor block above are given as parameters to
the
write
command. The LUN corresponds to the last value
assigned with the
lun
command. The VCB corresponds to
the last value assigned with the
vcb
command.
The Logical Block Address notifies the Target as to where the
data should be written on the device. The Transfer Length is
the number of blocks that the Target must transfer during the
Data Out phase. A zero represents 256 blocks.