National Instruments GPIB-PC - Manual (Page 141)

BASICA/QuickBASIC GPIB-PC Function Calls Section Four A
GPIB-PC User Manual 4A-66 ©National Instruments Corp.
BASICA/QuickBASIC BASICA/QuickBASIC
IBRSC IBRSC
Purpose: Request or release System Control
Format: CALL IBRSC (BD%,V%)
Remarks: BD% specifies an interface board. If V% is non-zero,
functions requiring System Controller capability are
subsequently allowed. If
V% is zero, functions requiring
System Controller capability are disallowed.
The IBRSC function is used to enable or disable the
capability of the GPIB-PC to send the Interface Clear
(IFC) and Remote Enable (REN) messages to GPIB
devices using the
IBSIC and IBSRE functions
respectively. The interface board must not be System
Controller to respond to Interface Clear sent by another
Controller.
In most applications, the GPIB-PC will always be the
System Controller. In other applications, the GPIB-PC will
never be the System Controller. In either case, the
IBRSC
function is used only if the computer is not going to be
System Controller for the duration of the program
execution. While the IEEE-488 standard does not
specifically allow schemes in which System Control can be
passed dynamically from one device to another, the
IBRSC
function would be used in such a scheme.
When IBRSC is called and an error does not occur, the
previous value of ist is stored in IBERR% .
Refer also to Table 2.1.