MATLAB: To Workspace block not returning results when simulating using SimulationInput objects

baseblockobjectsimulationinputsimulinksimulink.simulationinputtoworkspace

Why are To Workspace blocks not creating variables with the assigned names in the Base Workspace when I run my model using a 'SimulationInput' object?

Best Answer

When running a model using

out = sim(in)

where 'in' is a 'SimulationInput' object, a To Workspace block does not give the assigned variable name, e.g. 'simout', in the Base Workspace. Instead, the To Workspace block variable 'simout' is given as part of the 'SimulationOutput' object generated by 'sim', i.e. in this case 'out.simout'.

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MATLAB: Does “setVariable” in Simulink Test not update variables

In R2019b, the behavior of "setVariable" is modified such that it overrides only model variables (as opposed to MATLAB variables).

I attached a simpler model ("SimpleVars_R2019b.slx") to help illustrate this. This model has two "From Workspace" blocks, one set to "a" and one set to "evalin('base', 'b')".

If you call "findVars" on this model, only "a" is considered to be a model variable, even though both output their timeseries when run:

>> vars = Simulink.findVars('SimpleVars_R2019b')
vars = 
    VariableUsage with properties:
            Name: 'a'
          Source: 'base workspace'
      SourceType: 'base workspace'
           Users: {'SimpleVars_R2019b/From↵Workspace'}

The R2019b behavior provides stricter control of overrides and achieves parity with other Simulink tools. You will need to update the model to use variables which are recognized by Simulink.

Please update the "From Workspace" block variable parameter from "evalin('base', 'y_coordinate')" to just "y_coordinate". Then save the model and run the test file again.

You should observe that "setVariable" updates all of the variables now.

MATLAB: SimulationInput needs slx vs mdl file

After a lucky guess, I found that if I converted the *.mdl file to the newer *.slx file, then the code ran as intended.

The documentation for SimulationInput should be changed to state that it requires *.slx models.

I hope this post helps someone else someday with the same problem

Best Answer

Related Solutions

MATLAB: Does “setVariable” in Simulink Test not update variables

MATLAB: SimulationInput needs slx vs mdl file

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