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Control test instruments with Python

Martin Rowe, Senior Technical Editor- September 1, 2011

Many engineers write code to automate instruments and collect data. While you can use commercially available programming languages, you can also use open-source software tools to write your automation code.

An input signal excites a transducer to cause vibration in a mechanical system, which the oscilloscope measures.

Sinay Goldberg, an engineer in Ra’anna, Israel, needed to measure the frequency response of a mechanical system. Using an oscilloscope, a function generator, a current sensor, a piezoelectric transducer, and a laser vibrometer, Goldberg designed a measurement system that generates a stimulus signal and captures the mechanical system’s response signals (figure). He controls the oscilloscope and function generator through a USB port and with software written in Python (www.python.org). A pyvisa application provides a link to the instruments through a common programming interface (sourceforge.net/projects/pyvisa).

The function generator excites the mechanical system using a swept-frequency sine wave. When the mechanical system vibrates, the vibrometer converts mechanical motion into an electrical signal that the oscilloscope captures. After transferring the data to a PC, Goldberg’s Python application software converts the signals to the frequency domain for analysis.