National Instruments GPIB-PC - Manual (Page 117)

BASICA/QuickBASIC GPIB-PC Function Calls Section Four A
GPIB-PC User Manual 4A-42 ©National Instruments Corp.
BASICA/QuickBASIC BASICA/QuickBASIC
IBPAD IBPAD
Purpose: Change Primary Address
Format: CALL IBPAD (BD%,V%)
Remarks: BD% specifies a device or an interface board. V% specifies
the primary GPIB address of the device or interface board.
IBPAD is needed only to alter the value from its
configuration setting.
Only the low five bits of V% are significant and they must
not all be ones. Thus there are 31 valid GPIB addresses,
ranging from 0 to &H1E. An EARG error results if the
value of
V% is not in this range.
The assignment made by this function remains in effect
until
IBPAD is called again, the IBONL or IBFIND
function is called, or the system is rebooted.
When IBPAD is called and an error does not occur, the
previous value of ist is stored in IBERR% . The previous
primary address is returned in IBERR% .
Device IBPAD Function:
When BD% specifies a device, IBPAD determines the talk and listen
addresses based on the value of V% for use in all I/O directed to that
device. A device listen address is formed by adding &H20 to the
primary address; the talk address is formed by adding &H40 to the
primary address. Consequently, a primary address of &H10 corresponds
to a Listen address of &H30 and a talk address of &H50. The actual
GPIB address of any device is set within that device, either with
hardware switches or a software program. Refer to the device
documentation for instructions.
Board IBPAD Function:
When BD% specifies a board, IBPAD programs the interface board to
respond to the primary talk and listen address indicated by V% .
Refer also to IBSAD , IBONL , and Table 2.1.