National Instruments GPIB-SCSI-A, Руководство пользователя

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G Mode Functions Chapter 7
GPIB-SCSI-A User Manual 7-64 © National Instruments Corp.
rdext (continues)
The Logical Block Address notifies the Target as to where the
data should be read from the device. The Transfer Length is
the number of blocks that the Target must transfer during the
Data In phase.
During the execution of this command, if the GPIB-SCSI-A
encounters a phase which it did not expect, an EPHS error
indication results. For a list of the expected phases, refer to
the section titled Handling of SCSI Phases in G Mode in
Chapter 6, Programming in G Mode.
Refer to your SCSI device documentation for expected values
in each byte of the Command Descriptor Block and the SCSI
phases that the device creates during the execution of this
command.
If you enter
rdext?
, the GPIB-SCSI-A places the most
recent values for Logical Block Address and Transfer Length
into the buffer of the Command and Status Channel followed
by a <CR><LF>.
logical block address
represents a 32-bit unsigned
number. Correct values range from 0 to 4,294,967,296.
transfer length
represents a 16-bit unsigned number.
Correct values range from 0 to 65,535. If numbers that are too
large are entered, there is a syntax error in a number, or there
are no numbers, the GPIB-SCSI-A aborts the command with
an EARG error indication.
See Also: blksz, dtin, dtout, read, wrext, and writ.