Wednesday, December 13, 2006

What is GPIB (IEEE-488)?

L-com explains IEEE 488, also known as GPIB or HPIB

GPIB stands for General Purpose Interface Bus and is really a connectivity standard, known mostly by its IEEE file number: 488. Originally, this was a great way to connect machines because you could "daisy-chain" multiple GPIB cables together.

Nowadays, GPIB isn't used as much. However, there are still a lot of machines already in use, some of them very expensive or difficult to replace, that use the IEEE-488 interface. For that reason, GPIB cables, connectors, adapters, and other products are still in demand to keep these machines connected.

The IEEE-488 standard uses a "CN24" type connector, sometimes also called a Centronics 24, or a micro-miniature 24 pin connector. It has 24 pins arranged around a rectangular opening.

Most cables with this connector have both male and female interfaces at each end of the cable. This is how you can daisy-chain the cables together: by plugging the male end of the connector into a machine, you leave the female end exposed so you can plug another male cable into it. Usually the female side is in the same orientation as the male, called "normal orientation", but in cases where you want to daisy-chain in a straight line, it is usually best to get "reverse orientation" cables so you don't have to curve the cable up over the connector when you plug it in.

Of course, since there are so many newer bus standards, people are often looking for ways to convert GPIB to USB. L-com carries a GPIB to USB converter that can help you set up a laptop and plug it into machines that use the GPIB interface.

Because GPIB is such a rare interface nowadays, we often get questions about it, so please give us a call or send us an email if you want to learn more!

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