Interfacing a digital oscilloscope to a personal computer using GPIB

Summary form only given. This paper presents an undergraduate research project that involved the interface of a HP digital oscilloscope to an IBM PC using a National Instruments General Purpose Interface Board. The aim was to obtain a graphical representation of experimental waveforms onto the PC for storage and reproduction at a later date in reports, illustrations, etc. Plotter generated waveforms or Polaroid photographs have drawbacks as, for inclusion into documents, their copies are to be cut and pasted by trial and error, sacrificing quality. Well-scanned files of photos tend to be invariably large for handling if several of them are present. In the present work, the PC acted as the controller and the oscilloscope performed a talker/listener function in addressed mode. With the interface in place, the waveform data was digitized and transferred over the GPIB bus as an ASCII string, which was then converted to an array of voltage vs. time by writing a short code in Qbasic (or C) to implement the equations provided in the oscilloscope manual and the Preamble. The data was then plotted using Microsoft Excel (or Gnuplot). A comparison of the plotted waveform with the oscilloscope waveform indicated perfect agreement. Many aspects of data acquisition, instrumentation, interfacing, programming and WWW referencing made possible in this project enabled a senior undergraduate student fulfil his final project requirements for an EET degree