Simulink outputs variables but they are not being sent to the workspace.

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.

Answer 1

[David Avila]

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:

https://mycourses.aalto.fi/pluginfile.php/1137968/mod_resource/content/5/Simulink%20settings.pdf

I have to do this every time I make a new model till further notice

Edit: Grammar

[OUFQIR FARID]

thank-u-david...

it-was-very-helpful

[zaman sowmik]

how do you change the settings?

[LUCA LOMBARDO]

THANK YOU SO MUCH

[Filippo Bosi]

Thank you David, very cool!

[Alejandro ROJAS NORMAN]

You are a godsend

[Jonas Blomqvist]

Thank you!

[Hammed Omotoso]

cool

[Vincenzo D'Antuono]

Thanks !

[nina mahali]

thank you, saved me a lot of trouble!!

[Usama Hassan]

thanks man it works

[kumaran kumaran]

Thanks a lot David

[Yue Fan]

Thank you David! It makes sense now that I remember using Matlab+SimuLink this way being a lot easier 10 years ago, which is the last time I did this.

[Akash Ghimire]

Thanks a lot!

[Rick Dodder]

I was having the same problem, and DA's suggestion works when I run my simulation from the Simulink window using the run botton. I have the same problem if I run the simulation from the command line: run 'sim'. Any suggestions?

[samuel brown]

worked for me, MATLAB R2020b. Thanks!

[Ayush Jain]

Thanks man. Worked for me. I was stuck on it for more than 4 hours

[Gavin Moon]

thanks man worked for me when prof was not there

[Vishal Ahuja]

Thanks for sharing

[enrico Rothe]

THANK U DAVID ! u made my day :D

[Erika Nicole Vasquez Estrella]

you literally saved my project too :)

[Habby G]

Thank you for sharing this valuable information.

[Kevin Hobbs]

This does not work for me in 2022a. The fix the guide mentions is enabled by default and does not get rid of the ".out" in the diagram blocks.

[Andrew Melean]

Thanks David. Worked for me too.

[Hamoon maleki]

thanks david fixed my issue aswell 2021b

[Khaled Hassan]

Thank you very much, I was loosing my mind. This was very helpful

[Elmer]

Muchas gracias...

Answer 2

[Rostislav Teryaev]

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)

[zaman sowmik]

how do you change the settings?

Answer 3

[mete teke]

Thank a lot...

Answer 4

[Reid Spence]

By default, when you simulate a model, simulation results (including To Workspace blocks) are returned as a single Simulink.SimulationOutput object.

Option to return simulation results as single Simulink.SimulationOutput object - MATLAB (mathworks.com)

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:

1. 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)
2. 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.
3. 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.
4. Object methods: Calling plot() on the SimulationOutput object will open up Simulation Data Inspector. >>plot(out)