Besides plotting general expressions, Dymola 2013 FD01 allows the user a straightforward calculation of several relevant magnitudes in a plot window. To select this, right-click on a plotted signal and select Signal Operators. A menu will be displayed with the following list of applicable operators, which can be used over a user-defined time range:
- Minimum and Maximum values (Min and Max respectively).
- Slew Rate.
- Arithmetic and Rectified means.
- Root-mean-square (RMS).
- AC-Coupled RMS.
- First Harmonic.
- Total Harmonic Distortion (THD).
Figure 1. Selection and menu of Signal Operators from a plot window
When an specific operator is selected, a dialog box pops in order to allow the user to set the time range (or any other magnitude used as abscissa) over which the operator shall be applied. The operators First Harmonic and THD require, besides, entering the period of the signal.
If the minimum was larger than the maximum or if the horizontal range was out of bounds, an error message would be displayed. If everything is correct, the results will be seen in the plot depending on the operator executed, see figure 4.
Figure 2. Dialog box for Max signal operator
Figure 3. Dialog box for First Harmonic signal operator
Figure 4. Several operators applied to a signal (different horizontal ranges)
As it can be seen in the above figure, the default colour for horizontal range line and associated text is black. If there were more than one signal in the plot window, then the associated text would be shown in the same colour as the signal they correspond to.
Furthermore, it is possible to edit the results provided by these operators in two ways:
1. Use a drag-and-drop operation to move the horizontal line that represents the time range or its start and end points. Deleting a result can also be made by clicking on a time range and pressing the key “Delete”.
2. Right-click on a result and select one of the following options:
- Copy => copies the value to the clipboard.
- Edit => opens the dialog box to modify the horizontal range.
- Label Above Line: if not ticked, name of the operator and result are shown below the horizontal line.
- Delete: removes the whole operator result.
Figure 5. Edit options for a signal operator
The Signal Operator functionality has support in the scripting environment (except for THD and First Harmonic) using the function plotSignalOperator with the following general syntax:
plotSignalOperator("variablePath", signalOperator, startTime, stopTime)
Figure 6. Inputs and outputs of the function plotSignalOperator