Creating and Handling Signal Operator Probes On Signals in Watchlists

You can create signal operator probes on signals in watchlists. The simulation result is Knowledge parameters.

Important: You can add signal operators in plots also. See Applying Signal Operators by Commands. However, these are only applied to the plots and are no signal operator probes.

This task shows you how to:

Before you begin: You must have at least one watchlist. See Creating Watchlists with or without Live Plots. In the below scenario, we open Modelica.Mechanics.MultiBody.Examples.Elementary.DoublePendulum, and add the signal revolute2.phi to a watchlist.
See Also
About Behavior Experience
About Probes

Create a Signal Operator Probe On a Signal in a Watchlist

You can create signal operator probes on signals in watchlists.

Important: You can only work with signal operator probes in the tree - they are not visible from the Scenario window.

  1. In the tree, to add a signal operator probe on a signal in a watchlist, right-click the signal in the watchlist and select Create Signal Operator .

    Tip: You can add several signal operator probes to the same signal.
    Note: For a shared watchlist, you can work with the icon in the Scenario category or the icon in the Probes category, they are the same.

    The Create Signal Operator dialog box appears.
  2. Optional: In the Name field, enter a name of the signal operator probe.
    The name is presented as an alias for the signal operator in the results.
    Note: The default name is the type of the signal operator, selected in the next step.
  3. In the Type: list, select any of the following signal operators:

    • Minimum
    • Maximum
    • Arithmetic mean
    • Rectified mean
    • Root mean square
    • AC Coupled RMS
    • Slew rate
    • Value At End Time
    • Total harmonic distortion
    • First harmonic
    • Discrete difference
    • Fast Fourier Transformation
    • Moving Average

    In this scenario, select Minimum.

    For information on what signal operator types to select, and more information about them, see About Signal Operators.

    Note: The signal operator Value At End Time is not documented there, this operator is only available as a probe, and gives the value at the end time of the operator range as result.

    The dialog for the selected signal operator probe appears.
    Important: For all signal operator probes, you may consider the optional Step 4 below. For the signal operator probes not in the table, you can then click OK to validate the selection. For the signal operators in the table, you can perform additional selections before clicking OK:
    Signal Operator Probe Type Additional Options Available
    Total harmonic distortion See Step 5.
    First harmonic See Step 5.
    Fast Fourier Transformation See Step 6.
    Moving Average See Step 7.
  4. Optional: You can define the horizontal range, usually the time, over which the signal operator probe is applied:
    1. In the Minimum X: field, enter the minimum x value.
    2. In the Minimum X: field, enter the maximum x value.
    Important: If you don´t enter any values, the following is valid:
    • The horizontal range is automatically calculated when you simulate, to be as big as possible, from the start time to the stop time of the applied simulation.
    • If you change the simulation time, the horizontal range is recalculated automatically when simulating.
    Tip: For the Minimum and Maximum signal operator probe, you can set Minimum X: and Minimum X: to the same time. You then get the result as the value at that specific time.
  5. For the Total harmonic distortion and the First harmonic signal operator probes, you can enter additional options:
    1. In the Period length: field, enter the period length.

      Note: You cannot use Compute to compute the period length, since the simulation is not performed yet.

      If you don´t enter any value, the period length is automatically calculated when you simulate, as the length of the simulation.

      By default, the period length is 1.

    2. For the Total harmonic distortion signal operator probe, in the Number of harmonics: field, enter the number of harmonics.

      By default, the number of harmonics is 25.

    3. In the Interval length: field, enter the interval length.

      By default, the interval length is 0.02.

      The interval length together with the horizontal range gives the Number of points.

    4. Select Window presentation.

      Default is Rectangular, which gives equal weight to all points. Other alternatives are Hamming, Hann, and FlatTop.

  6. For the Fast Fourier Transformation signal operator probe, you can enter additional options:
    1. In the Max frequency: field, enter the maximum frequency.

      The maximum number that can be entered is displayed after the field.

    2. Select Window presentation.

      Default is Rectangular, which gives equal weight to all points. Other alternatives are Hamming, Hann, and FlatTop.

    3. In the Interval length: field, enter the interval length.

      By default, the interval length is 0.02.

      The interval length together with the horizontal range gives the Number of points.

  7. For the Moving Average signal operator probe, you can enter additional options:
    1. In the Interval length: field, enter the interval length.

      By default, the interval length is 0.02.

    2. To compute and display first-order derivatives, activate Differentiate signal.

      By default, this option is cleared.

  8. Click OK to validate.
    The signal operator probe is displayed under the watchlist in the Scenario category and in the Probes category of the tree (see image below). If you have entered minimum and maximum, they are displayed as well, after the signal.
  9. To delete a signal operator probe, right-click the signal probe icon in the tree and click Delete.

    The signal operator probe is also deleted if you remove the signal it works on from the watchlist, or remove the whole watchlist. To remove a signal from a watchlist, see Creating Watchlists with or without Live Plots.

    Notes:
    • If you remove a signal from a watchlist, all signal operator probes on that signal are deleted.
    • For a shared watchlist, you can work with the icon in the Scenario category or the icon in the Probes category, they are the same.
    Important: If you change or delete anything in a shared watchlist definition, it is also changed or deleted in all other scenarios where it is used. To create a probe that is not shared, you must copy it. For more information about copying probes, see Copying and Pasting Excitations and Probes between Scenarios.

  10. To create probe results, perform a simulation. See Simulating and Generating Results.
    The probe results are created under the Result category to display the result. Below a scenario with minimum signal operator probe and result marked.
    Note: For min and max signal operator probes, a separate signal operator probe result is created for the time when the minimum/maximum value is reached. If the minimum/maximum value is reached several times, the latest time is stored and presented.
    Tip: To display values for parameters in the tree, you must activate the Display values in the specification tree preference from Me > Preferences > App Preferences > 3D Modeling > Multi Discipline Automated Engineering > Basics, the Parameters & Relations tab, the Parameters tree view group.


    For the different signal operator probes, you get the following probe results when simulating:
    Default Signal Operator Probe Name Probe Results When Simulating Comment
    Min [signal].Min Min value.
    [signal].Min\time Time at min value.
    Max [signal].Max Max value.
    [signal].Max\time Time at max value.
    Aritmetic Mean [signal].Aritmetic Mean Arithmetic mean value.
    Rectified Mean [signal].Rectified Mean Rectified mean value.
    RMS [signal].RMS Root mean square value.
    ACCoupledRMS [signal].ACCoupledRMS AC Coupled RMS value.
    SlewRate [signal].SlewRate Slew rate value.
    DiscreteDifference [signal].DiscreteDifference

    Discrete difference values. The result is displayed as a string with the following format:

    [x1, y1;x2, y2;…;xn, yn]

    The x values are the time values, and the y values are the corresponding discrete difference values.
    First harmonic [signal].First harmonic Value of the first harmonic.
    THD [signal].THD Value of THD (Total Harmonic Distortion).
    FFT [signal].FFT

    Values of the FFT (Fast Fourier Transformation). The result is displayed as a string with the following format:

    [x1, y1;x2, y2;…;xn, yn]

    The x values are the frequencies, and the y values are the corresponding powers.
    MovingAverage [signal].MovingAverage

    Moving average values. The result is displayed as a string with the following format:

    [x1, y1;x2, y2;…;xn, yn]

    The x values are the time values, and the y values are the corresponding average values.
    Value at End Time [signal].Value at End Time Value at end time of interval.
    Notes:
    • The signal operator probe result values are knowledge parameters.
    • If the signal has a known magnitude/unit from Modelica.SIUnit or is of a basic type (Real, Integer, Boolean, or String), the signal operator probe result gets the corresponding Knowledge type. If not, it is a String (case for enumeration, or unknown type).

Edit an Existing Signal Operator Probe Definition

You can edit an existing signal operator probe definition.

To edit an existing signal operator probe, do any of the following:
  • Right-click it in the Scenario category of the tree and select Edit Signal Operator.
  • Double-checked it in the Scenario category of the tree.
    Note: You may have to double-click twice, once to select the Scenario category, once to select the signal operator probe.
The Signal Operator dialog box appears. Here you can edit the definition.
Note: For a shared watchlist, you can work with the icon in the Scenario category or the icon in the Probes category, they are the same.
Important: If you change or delete anything in a shared watchlist definition, it is also changed or deleted in all other scenarios where it is used. To create a probe that is not shared, you must copy it. For more information about copying probes, see Copying and Pasting Excitations and Probes between Scenarios.

Change the Result of a Signal Operator Probe

You can change the result of an existing signal operator probe.

Before you begin: The signal operator probe value must be unlocked. See next section.
  1. Right-click the icon for the signal operator probe result in the Result category of the tree and select [path+signalname].object > Definition.

    Tip: You can also double-click the icon. You might have to double-click twice.

    An Edit Parameter dialog box appears and lets you edit the signal operator result.
  2. Click OK to confirm the change.

    Important: Any change of the simulation result of a signal operator probe is local, even if the probe is a shared probe. The result of probes in other scenarios is not changed.

Locking or Unlocking a Signal Operator Probe Result Knowledge Parameter Value

You can lock or unlock a signal operator probe result. This means that the knowledge value of the signal operator probe cannot be modified from other apps.

  1. To lock a signal operator probe result, right-click the icon for the signal operator probe result under the Result category in the tree and select [path+signalname].object > Lock.
  2. To unlock a signal operator probe result, right-click the icon for the signal operator probe result under the Result category in the tree and select [path+signalname].object > Unlock.

Important: Any change of the simulation result of a signal operator probe is local, even if the probe is a shared probe. The result of probes in other scenarios is not changed.

Edit Formula of the Knowledge Parameter of a Signal Operator Probe

You can edit the formula for the knowledge parameter of a signal operator probe result.

To edit the formula for the knowledge parameter of a signal operator probe result, right-click the icon for the signal operator probe result under the Result category in the tree, and select [path+signalname].object > Edit Formula. .
The Formula Editor appears to let you edit the formula. For information about formulas, see the Knowledge Basics: Managing Relations: Formulas: Creating a Formula.
Tips:
  • You can click an item in the tree and, from the Tools section of the action bar, click Formula to display knowledge parameters and related formulas for that item.
  • There might be more knowledge commands available in the context menu of the signal operator result icon. For information about them, see the Knowledge Basics.

Important: Any change of the simulation result of a signal operator probe is local, even if the probe is a shared probe. The result of probes in other scenarios is not changed.