Simulink outputs variables but they are not being sent to the workspace.
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Michael Colantonio
on 2 Apr 2019
Answered: Reid Spence
on 26 Jul 2024
While using my PC at home I am using 'to workspace' blocks in my diagram with save format array. When I run the simulation i get the following the the command window:
ans =
Simulink.SimulationOutput:
Vin: [2002x1 double]
Vout: [2002x1 double]
t: [2002x1 double]
tout: [2002x1 double]
SimulationMetadata: [1x1 Simulink.SimulationMetadata]
ErrorMessage: [0x0 char]
Undefined function or variable 't'.
Error in P1_2 (line 79)
plot(t,Vin,t,Vout)
It seems to me that simulink is outputting the variables but they are not appearing in the workspace and therefore it thinks they are undefined. I tried running the simulation on a computer at my university and it worked. I tried reinstalling Matlab on my home PC and it still doesnt work. Version 2019.
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Accepted Answer
David Avila
on 21 Dec 2019
Edited: David Avila
on 21 Dec 2019
If you are running 2019a, the Simulink default settings for the "To Workspace" block have been changed and would need to be set back from being a single simulation output:
I have to do this every time I make a new model till further notice
Edit: Grammar
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More Answers (3)
Rostislav Teryaev
on 2 Apr 2019
First of all, you have to assign a structure Simulink.SimulationOutput to some variable
temp = Simulink.SimulationOutput;
Next, you need to access field t or Vin of this structure
temp.t
temp.Vin
To use plot you want this
temp = Simulink.SimulationOutput;
plot(temp.t, temp.Vin, temp.t, temp.Vout)
Reid Spence
on 26 Jul 2024
By default, when you simulate a model, simulation results (including To Workspace blocks) are returned as a single Simulink.SimulationOutput object.
You could disable this behavior with the "ReturnWorkspaceOutputs" parameter of models, however I would recommend against it as the SimulationOutput object has several advantages over returning To Workspace values as their own variables:
- Metadata: The SimulationOutput object stores helpful metadata about a simulation, such as warning, errors, timings, etc. It can be very helpful to refer to these to understand a simulation, especially if some time has passed between when you ran the simualtion and when you are reviewing the results. Access metadata of simulation runs - MATLAB (mathworks.com)
- Differntiate from other results: The SimulationOutput object acts a helpful container of all results related to one simulation. That container allows you to easily know which outputs and metadata are associated from the same simulation and more easily differentiate them from other simulations you may have run. This avoids confusion and mixing up results from previous simulations.
- Support for changing workflows: The SimulationOutput object provides better support for switching between serial simulation, parallel and batch simulations, and deployed simulations. When you return results as a single simulation output, the syntax to simulate a model programmatically is the same for the sim, parsim, and batchsim functions.
- Object methods: Calling plot() on the SimulationOutput object will open up Simulation Data Inspector. >>plot(out)
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