How do I get the output of a simulink run via the "Output" Data Import/Export section?

I am trying to set up my output in a simulink simulation in order to use the "Output" option in the Data Import/Export configuration Parameter.

My understanding is that if I put an "Output" sink in my model (see below):

And tick the configuration parameter options as shown below:

I should see yout in the workspace. Yet, the only array that I see is tout as shown below:

Simulink.SimulationOutput:

tout: [1000006x1 double]

SimulationMetadata: [1x1 Simulink.SimulationMetadata]

ErrorMessage: [0x0 char]

I understand that I can use the "To Workspace" block to get my output exported to workspace but isn't the method described above supposed to work as well? Thanks.

[Fangjun Jiang]

Is the Outport block in root level?

[scc28x]

Thanks for reply. Yes, it is in the root level. What you see in the snapped picture is all there is in the system.

[Fangjun Jiang]

I don't have R2021a installed. But this should be straightforward. Un-check all other checkmarks and complete a simulation and check it again.

[scc28x]

Hi, I did uncheck all other checkmarks and I did get yout in my matlab workspace. Thanks. But could you tell me what the issue is? Which specific item stops the passing of Output to the workspace? Thanks.

[Fangjun Jiang]

None of the other checkmarks affect "yout" in older versions. You can try to see if it behaves differenty in R2021a. Likely items are "Log Dataset data to file" and the one related to "Simulink Data Inspector". Make sure to clear "out" from workspace every time you re-run the simulation.

[scc28x]

Thanks again. So this is essentially a bug?

[Fangjun Jiang]

You have not found the cause yet. Is it a human mistake (not run a new simulation after checking "output")? Or, is it affected by checking another item (if Yes, which one? There are only a few items so try and error to determine the exact one).

[scc28x]

Good point. I re-ran a few sims and determined that it was caused by having selected "Log Dataset data to file: out.mat". There is no "yout" in the workspace after sim whenever this selectBox is ticked.

[Fangjun Jiang]

It might make sense because if saving to a file, why also saving to workspace. But it was not mentioned in the R2021a document below.

Another factor could be that the size of the data set is too big to fit in the momory. Do you have lots of outports? "1000006x1 double" indicates you have more than 1e6 data points for every signal.

Try a simple and small example. If it still behaves the same, then you can attach the model to the Mathworks Tech Support to report this as a pontnetial "bug". They might have an explaination or acceept it is indeed a "bug".

https://www.mathworks.com/help/releases/R2021a/simulink/gui/output.html

https://www.mathworks.com/help/releases/R2021a/simulink/gui/log-dataset-data-to-file.html

Answer 1

[Harshit Rastogi]

I understand that you are trying to get yout in the workspace. So, for that you have to uncheck the "Log Dataset data to file" . Otherwise the output will be saved only in the file and you wont get it on the worspace. What actually happens is that it adds all the checked parameter data to the 'out.mat' file. Which means, the 'logsout' output that you need is also stored in 'out.mat' and can be accessed by loading the .mat file in workspace.

An enhancement request has been submitted for a feature where the variables show up in the base workspace and in the '.MAT' file.

[Fangjun Jiang]

I tried it in R18b and R19b. It happened when saving format is "Dataset". If format is "array", "yout" is always saved to workspace no matter "Log Dataset data to file".

Maybe now I undestand the meaning of "Log Dataset data to file", which seems to mean

1. If a variable is checked under "save to workspace or file"
2. and, if the saving format is "dataset" and that variable is supported by "dataset"
3. and, if "Log Dataset data to file" is checked

Then, that variable is saved to the .mat file but no to the workspace.

This is quite a complex combination and logic. Anywhere in the document might indicate this?