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GPIB
is a short range digital communications bus that has been in use
for nearly 50 years. Originally created for use with automated test
equipment, the standard is still in wide use today. This is due
to the fact that it remains one of the very few methods of controlling,
interfacing, and integrating various different instrumentation devices
produced by different manufacturers in a uniform and generic fashion.
In
the late 1960s Hewlett-Packard developed the HP Interface Bus (HPIB)
to enable easier interconnection between instruments and controllers
such as computers. In 1975 the bus was standardized by the Institute
of Electrical and Electronics Engineers as the IEEE Standard
Digital Interface for Programmable Instrumentation, IEEE-488-1975
(now IEEE-488.1).
IEEE-488.1
formalized the mechanical, electrical, and basic protocol parameters
of GPIB, but said nothing about the format of commands or data.
In 1987 the IEEE-488.2 standard, Codes, Formats, Protocols,
and Common Commands for IEEE-488.1, provided for basic syntax and
format conventions, as well as device independent commands, data
structures, error protocols, and the like. Another standard SCPI
was introduced in the 1990s for device commands. In 2003 the standard
was upgraded to support high speed data rates of 8MB/S known as
HS-488. |
The
LX700 System Controller provides the internal firmware for handling
the GPIB commands and processing. Each module within an LX700
mainframe appears as a sub-instrument. GPIB commands are typically
issued by user scripts as controlled from a PC using custom
software. A LabVIEW driver will also be available in the future
for system interface virtualization.
The GPIB interface for each module is unique, due to the specialization
of each module and its characteristics and features. As new
future modules are released, the firmware for the LX700 mainframes
will be revised and updated to provide GPIB support for each
new module. The firmware updates can be easily downloaded and
installed by the user as binary hex code for flash memory.
The GPIB functionality is most effective when multiple instruments
of various kinds must be integrated into an overall larger system,
and controlled by a central software program/script. Since the
LX700 Win32 application software is not involved; the management,
control, and processing requirements must be met by the user's
own custom software. While GPIB is very effective for general
mode, option, and feature control, data processing requirements
can be much more demanding and highly numerical. |
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