The voltage steps are generated on OD1 by clicking on the buttons on the GUI. The observed waveforms are shown below, showing the voltage variation across the inductor in each case. It can be observed that when a 5 to 0 volt step is applied, the polarity of the voltage across the inductor is reversed and the voltage goes to negative immediately. After that the voltage reduces exponentially, driving a current through the resistor. The resulting wave form is fitted with V = Vo x exp(R/L * t) to extract the R/L value. The value of inductor is calculated from  that.