If you use any kind of box-based test equipment—oscilloscope, multimeter, power supply, network analyzer, function generator, etc.—you’ve probably used GPIB sometime in your career. Most automated test systems built for production still use the bus, in part because of its massive installed base. While some new instruments don’t have GPIB as a standard computer interface, many still do.
Developed by Hewlett-Packard in 1975 and originally called HPIB (Hewlett-Packard Interface Bus), GPIB became IEEE-488 in 1987. That standard, now known as IEEE 488.1, defined the hardware interface. IEEE-488.2, ratified in 1992, defined communications protocols for the bus.
Early GPIB interfaces let you control test equipment from HP controllers such as the HP 9485. In 1976, National Instruments announced its first product, a GPIB interface for the PDP11.
When the IBM PC came on the scene in 1981, engineers began using it to control test equipment once ISA-GPIB interfaces were available. You can still get them today should you need one for a legacy test system. Page 7 shows some of those legacy GPIB interfaces.
GPIB interfaces have continued to move with PC technology. Today, you can use PCI, PCIe, PXI, USB, LAN, or other GPIB interfaces. National Instruments even shows GPIB cards for PCMCIA and ExpressBus. Here’s an ad from Test Measurement World in 1994 showing the PCMCIA-GPIB interface.
The following pages show GPIB interface offerings arranged by bus. Each page has a link that lets you return to this page. Captions under each image provide links to each product’s page where you can get more information. Prices are included where available online.
Not everyone prefers GPIB. Reasons include the cost of adding a GPIB interface to a computer and because GPIB is a parallel bus, some engineers, don’t like the heavy cables and connectors. On the other hand, some engineers like GPIB’s ruggedness and difficulty in removing the cables.
Many people, including Tom Burke here on EE Times, have written about the demise of GPIB. But, you can’t keep a good bus down.
The proliferation of laptop computers has brought about a need for the USB-GPIB interface. Even many desktop computers use USB-GPIB interfaces because they’re easy to install. You don’t have to open the computer to install the interface. If fact, you son;t even have to shut the computer off to install and use a USB device.
If your PXI or PXIe uses an embedded controller, chances are is already has a GPIB port. But, there are situations when you need to add GPIB because you’re using, say, and MXI interface and controlling the system from a desktop computer. Or, you have a slave chassis that needs a GPIB interface because of its proximity to test instruments. Either way, you can add a PXI-GPIB interface card.
For the past several years, PC plug-in instruments cards haven’t received much coverage, in part because they’re a stable product class. Yet, new PCI and PCIe cards keep coming to market. That means engineers are, in fact, still using PC plug-in cards in commercial or industrial PCs. In the case of GPIB, adding an interface card has become routine. Engineers who use these cards do so because they don’t want a dangling USB-GPIB module in a test rack on the production floor.
With PCIe (PCI Express) so popular in today’s desktop computers,, it’s no surprise that the test industry has added the bus to its portfolio of GPIB options.
Some applications require that you control test equipment over a LAN. While many recent instruments have Ethernet ports, many legacy instruments have GPIB but not LAN ports. That’s where you need an Ethernet-to-GPIB interface.
While the products shown on the previous pages cover most applications, there are situations that require something different. The earliest PCs used the ISA bus and engineers used ISA cards—including GPIB interfaces—to automate test equipment. Some of those systems are still in use and may require that spare parts be kept on hand.
ISA-to-GPIB converters are also available from National Instruments ($630).
Have you ever encountered a situation where you have a test setup with GPIB and then found that you needed to attached another bus? Thus, you needed a reverse GPIB interface. These situations may be rare, but you can find products to cover you when they occur. For Example, ICS Electronics offers the 4865B ($535), which lets you add a LAN-based instrument to a GPIB bus. The LAN-based instrument will look like a GPIB instrument to a system’s GPIB controller. The company also manufactures a GPIB-to-I2C interface.
To you still use an laptop computer with a PCMCIA or ExpressCard slot? If you do, you can still add GPIB through those buses. National Instrument offers both.
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