S Mode Functions
Chapter 5
GPIB-SCSI-A User Manual
5-76
© National Instruments Corp.
rsc - Request/Release System Control
Type:
Initialization function
Purpose:
Use
rsc
if some other device in your GPIB system is System
Controller.
Format:
Bit
7
6
5
4
3
2
1
0
Byte
0
Opcode = D1H
1
Reserved
2
Reserved
3
Reserved
Mode
4
Reserved
5
Reserved
Remarks:
If Mode is 1, the GPIB-SCSI-A configures itself to be the
GPIB System Controller. If Mode is 0, the GPIB-SCSI-A
does not configure itself as System Controller.
As System Controller, the GPIB-SCSI-A can send the
Interface Clear (IFC*) and Remote Enable (REN*) messages
to GPIB devices. If some other Controller asserts Interface
Clear, the GPIB-SCSI-A cannot respond unless it is not
configured as System Controller.
In most applications, the GPIB-SCSI-A is System Controller.
In some applications, the GPIB-SCSI-A is never System
Controller. In either case,
rsc
is used only if the
GPIB-SCSI-A is not going to be System Controller while the
program executes. The IEEE 488 standard does not
specifically allow schemes in which System Control can pass
from one device to another, however,
rsc
can be used in such
a scheme.
The GPIB-SCSI-A configures itself to be System Controller at
power-on.
