Chapter 7
G Mode Functions
© National Instruments Corp.
7-105
GPIB-SCSI-A User Manual
vcb - Set Vendor Unique Control Byte Bits
Type:
SCSI Configuration function
Syntax:
vcb value
<CR>
or
vcb?<CR>
Purpose:
Use
vcb
to change the value that the GPIB-SCSI-A uses in
the upper two bits of the Control Byte portion of any
Command Descriptor Block created for communication with
any SCSI device.
Remarks:
This command is in effect for any of the high level
GPIB-SCSI-A commands that communicate with the SCSI.
This command is only used if the manufacturer of your SCSI
device has indicated that the device expects some value in the
two bits in the Control Byte of the command descriptor block
of each command. For more information on the Control Byte
or the command descriptor blocks, refer to Appendix D,
Operation of the SCSI. The default value for
vcb
is 0.
If you enter
vcb?
, the GPIB-SCSI-A places the current value
of
vcb
into the Command and Status Channel buffer followed
by a <CR><LF>.
value
represents a 2-bit unsigned number. Correct values
are from 0 to 3. If a number that is too large is entered, or if
there is no question mark and no value following the
command, the GPIB-SCSI-A aborts the command with an
EARG error indication.
The assignment made by this function remains in effect until
you call
vcb
again or turn off the GPIB-SCSI-A.
See Also:
Appendix D, Operation of the SCSI.
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Страница 355: ...Appendix C Operation of the GPIB National Instruments Corp C 7 GPIB SCSI A User Manual Figure C 2 Linear Configuration ...
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