IVI

Benchmark Example: Measuring the magnitude frequency response of a system

Consider the task of determining the frequency response of an unidentified system. This requires both a waveform/function generator to generate sine waves at various frequencies and a DMM or an oscilloscope to measure the output voltage(s) of the system under test. You can see below the pseudo-code for a test program that uses high-level instrument driver calls to program a function generator and oscilloscope.

• Initialize and Configure Oscilloscope
• Initialize and Configure Frequency Generator
• While (frequency < EndFreq)

BEGIN LOOP

• Generate Sine Wave (Frequency Generator Channel 1)
• Read Stimulus Waveform (Scope Channel 1)
• Read Response Waveform (Scope Channel 2)
• Calculate Magnitude and Phase Difference between Stimulus and Response
• Store Magnitude and Phase
• Increase Frequency

END LOOP

• Plot Magnitude and Phase Difference
• Close Oscilloscope
• Close Frequency Generator

Pseudo-code and test setup for swept sine test
This test process was implemented using a HP 33120A function generator and a HP 54645D oscilloscope. The table below highlights the difference in performance between IVI and traditional VXIplug&play drivers for this particular test.

Difference in Performance

	State Caching	Test Time (seconds)	Performance Difference
	Off (Traditional VXIplug&play driver)	35.0	N/A
	ON (IVI driver)	13.2	265%