Hardware Reference
In-Depth Information
Figure 8.8
Simplified schematic diagram of an IEEE-488/GPIB controller
(200H + 100H) = 300H (or 768 decimal). Happily, PCI and PCMCIA cards are
'plug-and-play' compatible and therefore hardware base address selection is not
required. The simplified schematic diagram of an IEEE-488/GPIB controller is
shown in Figure 8.8.
IEEE-488 software
In order to make use of an IEEE-488 bus interface, it is necessary to have a resi-
dent driver to simplify the task of interfacing with control software. The requisite
driver is invariably supplied with the interface hardware (i.e. the IEEE-488
expansion card) and is installed when the hardware is fitted. Thereafter, soft-
ware will be able to communicate with the card using calls to a standard library.
The user and/or programmer is then able to access the facilities offered by the
IEEE-488 bus using appropriate commands and function calls. For example,
the following commands might be used with a multimeter (e.g. Fluke 45):
*RST 'Reset the meter
VDC 'Select Volts DC Range
VAL? 'Take a measurement and send it over the GPIB bus
Standard libraries are provided in order to simplify the process of pro-
gramming
IEEE-488
bus
instruments.
The
following
is
an
example
of
a
