New-Tech Europe Magazine | Q3 2021 | Digital Edition

Figure 2: Oscilloscopes like the Analog Discovery Pro from Digilent come with multiple instruments like waveform generator or analyzers and can be scripted for automated testing. Credit : Digilent

Figure 1: A simple power measurement system Credit : Digilent

One Software for All Instruments WaveForms comes with twelve built-in software instruments, like an oscilloscope, a pattern- and a waveform-generator (which, for example, could create the test signal for our power measurement), a controllable power supply, I/Os, logic-, spectrum-, network-, impedance- and protocol-analyzers, as well as a voltmeter and a data logger. This way users can capture, record, analyze, document, and generate mixed-signals and mixed-domain signals. Additionally, the WaveForms application includes a script editor tool, which allows custom programming of the instruments in JavaScript. Sometimes, however, like in the case of the power-measurement example, it is not even necessary to create a script. The software’s oscilloscope instrument contains so-called Math channels, which perform the calculations and plot the result alongside the measurements. So, to display the total power of the circuit, simply writing “(C2 – C1) * C1 / RS“ in the “Script” field of a dialog is sufficient, with RS being the value of the shunt resistor. This equation computes the current by dividing the voltage VS across the sensing resistor (Channel 1) by its resistance value and then multiplies the result with the voltage across

Script Module Eases Automation

the combined load (capacitance and resistance) derived by subtracting the voltage VS (Channel 1) from the voltage VG across the load (Channel 2). In the same window, also the unit of the signal and the range of the channel in units per division can be set. It is also possible to rename the measurement channels and the math channels for more clarity (Figure 3). Additional calculations, like the power consumption of the resistor RL, can be performed as well by simply adding more math channels. Besides arithmetic operations, the module also supports trigonometric operations, and others.

Each of the Waveforms’ instruments can be run by scripts. By writing JavaScript code and executing it in the “Script” instrument, engineers can control any other instrument through extensive Application Programming Interfaces (APIs). This way, it is also possible to configure and run several instruments simultaneously in an easily repeatable way. The script instrument not only allows to control the instruments and to acquire data. It also includes a plot pane, where users can integrate the data from many different instruments and display them

Figure 3: The math channels in the software makes simple calculations using the inputs to the oscillo-scope easy. Credit : Digilent

New-Tech Magazine Europe l 31