IEEE-488 instrument bus | GPIB


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IEEE-488 refer to the Institute of Electrical and Electronic Engineering standard number 488 also known as General Purpose Interface Bus (GPIB). This is a digital communication 8-bit parallel multi-master interface bus specification invented by Hewlett-Packard (HP).

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The IEEE-488 instrument bus is most often used to connect computer and personal computers to measurement instruments, plotters, and other such peripheral devices in testing laboratories. In this way, automatic measurement, analysis, data processing and recording can be accomplished.

Function of IEEE-488:

The functions of the connected devices can be classified into three types: controller, talker, and listener. Each device must be equipped with at least one of these three functions.

As an example of a simple system, the computer performs the controller function as required and specifies the instrument as the talker, and itself as the listner, and then receives the measurment data. After completion of data transmission, the disgnations for both talkers and listener are released. When data analysis is complete, the computer specifies itself as the talker and the plotter as the listener. It then sends the analysis data to the plotter for recording.

The bus line names and functions are shown:

Advantages:

  • Simple hardware interface

  • Allows mixing of slow and fast devices

  • Rugged cables, in some location large heavily protected cables are an advantage

Disadvantages:

  • High cost and limited availablity

  • Mechanicaly bulky connectors and cables

  • Lack of command protocol standards

  • Non mandatory galvanic isolation between bus & devices