Developed by Hewlett Packard in the early 1970’s, General-Purpose Interface Bus, or GPIB products bridge computers to stand-alone instruments to create automated data acquisition systems used in laboratory test equipment and industrial complexes. While more people may be familiar with Universal Serial Bus (USB) cables, GPIB connectors came first and are still considered the standard, if only for their industrial-grade usage and backing by the IEEE standard 488.

The GPIB interface enables your computers to share data and control information from many peripherals. This interface lets your computers acquire data from test instrumentation, or send data or instructions to machines to automate production processes. There are three basic categories of GPIB instruments to consider when connecting your network:

1. The GPIB controller and converter directs the communication occurring between devices;

2. GPIB USB switches act like the old phone company operators, manually connecting a GPIB control with other devices; and

3. GPIB extenders and expanders let your system grow beyond the IEEE 488 standard set for GPIB devices.

Action Steps
The best contacts and resources to help you get it done

Avoid crossed signals in your test systems with a GPIB controller

GPIB controllers and interface boards direct the communications occurring between the computer and instrumentation, routing and scheduling the signals in an orderly manner. GPIB converters translate data from one bus type to the GPIB bus to smooth communication between otherwise incompatible systems.

I recommend: CONTEC leads in developing and manufacturing automation control systems for factory and laboratory environments. Measurement Computing prides itself in providing low-cost, simple-installation solutions to customers. Its interface allows you to connect your computer to up to 14 instruments.

Direct signal traffic quickly with GPIB cable and switches

Use GPIB switches like an electronic switchboard operator to route data from several GPIB controllers to one or more GPIB devices, or to a single GPIB controller to operate multiple systems.

I recommend: Pickering Interfaces claims to offer the widest range of switching modules available. L-com offers one of the world’s largest assortments of GPIB Products.

Stretch the reach of your system with GPIB extenders and expanders

IEEE standard 488 limits GPIB systems to a maximum interface of 14 devices, and a maximum cable length of 20 meters. GPIB expanders augment the max interface, while extenders lengthen the cable limit to several kilometers, while maintaining the overall performance of the GPIB program.

I recommend: National Instruments manufactures an expander that accommodates up to 28 devices. Keithley Instruments produces extension modules that allow you to shield your computer control system from a harsh environment by building an ancillary chassis.

Tips & Tactics

Helpful advice for making the most of this Guide

• •  Plan out your computer system as far ahead as possible: not only the computing systems and instruments, but the connections to connect them (PCI, GPIB, USB) and the software to run them. Manufacturers also supply their own ASICs so research their proprietary programming to ensure compatibility with your internal operations before paying full GPIB price.