The General-Purpose Interface Bus (GPIB), also known as IEEE-488, is a standard for a parallel communication bus that was specifically designed to connect and control electronic test and measurement instruments. Developed by Hewlett-Packard in the late 1960s as HP-IB, it was later standardized and became the dominant interface for instrument automation for several decades. GPIB uses a 24-pin connector and thick, shielded cables. A key physical feature is its "piggyback" connector design, which allows multiple instruments to be connected in a linear or star-shaped "daisy chain" to a single GPIB controller card in a computer.
The bus architecture allows one controller (the master) to manage up to 14 instruments (the slaves). Each instrument on the bus is assigned a unique address (from 0 to 30) so that the controller can direct commands to a specific device. Communication is parallel, meaning 8 bits of data are sent simultaneously over separate wires, which made it relatively fast for its time.
Although it has been largely superseded in new designs by more modern, user-friendly, and faster interfaces like USB and LAN (Ethernet/LXI), GPIB is still found on a vast amount of existing lab equipment. As a result, many test systems still utilize it, and modern control software and VISA drivers continue to provide full support for GPIB communication to ensure backward compatibility.