Saving data at the end of a simulation to use it at the beginning of another simulation

I am trying to save in a SIMULINK variable (not workspace) the last data showed in a Display block (as Limit data point to last) in a first simulation, and then run a second simulation that uses that value.

To do this I have written the following code in InitFcn (callback function), in Model properties. Tha value I want to save in the first run is "Prueba_no_modules_out", so I was thinking to structure the code as follows: while this variable does not exist in Simulink, I use a inicialization value (%1). In the second run, the input variable (Prueba_no_modules) uses the last simulation data output (%2), because "Prueba_no_modules_out" already would exist.

code in InitFcn:

if ~exist('Prueba_no_modules_out')
     Prueba_no_modules = 4; %1
else
     Prueba_no_modules = Prueba_no_modules_out; %2
end

My problem comes out when trying to save "Prueba_no_modules_out" as a variable in SIMULINK to use it in InitFCN. "Prueba_no_modules" works propertly (it is a variable in a constant block).

But I tried to generate the variable "Prueba_no_modules_out" using "To workspace", and although it does generates it in workspace, InitFcn does not recognizes it as "out.Prueba_no_modules_out" neither as just "Prueba_no_modules_out".

I have found this post where it speaks about "SimState" https://es.mathworks.com/matlabcentral/answers/181663-how-to-save-the-last-value-of-a-simulation-in-a-mat but I do not really understand it...

Hope I explained well.

Thank you

- Ester

Answer 1

[Fangjun Jiang]

Ctrl+E to open configuration parameters, Data Import/Export, un-check "Single simulation out" will save the "To Workspace" to "Prueba_no_modules_out", not "out.Prueba_no_modules_out"

[Ester Panea Murillo]

Thank you very mucha Fangjun. Solved the problem of the variable.

Now a error occurs when I equal the value of the target variable (Prueba_no_modules) with the output variable of the first simulation (Prueba_no_modules_out).

if ~exist('Prueba_no_modules_out')
     Prueba_no_modules = 4; %inicialization value
else
     Prueba_no_modules = Prueba_no_modules_out;  %HERE THE SOURCE OF THE ERROR
end

Maybe it is because I have to try instead:

if ~exist('Prueba_no_modules_out')
     Prueba_no_modules = 4; %inicialization value
else
     Prueba_no_modules = getdatasamples(Prueba_no_modules_out,1); %MODIFICATION
end

??

...since the format of "Prueba_no_modules_out" is timeseries (1x2), and I only need value at cell column 2:

I'll try tomorrow - I'll write if it was that

Thank you again,

-Ester

[Fangjun Jiang]

You can change the "save format" of the "To Workspace" block to array.

[Ester Panea Murillo]

Thank you very much Fangjun, it works propertly with array format.

Now I forgot that I needed other "out." datas to be exported to workspace, and then to excel by "xlswrite" command, that now with this configuration (un-checking "Single simulation out" ) cannot be exported.

Is there any way to export this data from simulink directly to excel? In order to not need "out." data object, and the post-processing code in matlab workspace (I mean, running the script after the simulink run is completed to export the data to Excel).

I am thinking in two possible solutions:

1) Using "To File" (*mat) block. But this is implying to complicate the code (And it would require post-processing). And I am having troube to export "struct" format (generated by "To file" block, whose input is a bus with all the data I need to export) data to excel file...

2) Using MATLAB function in which to enter all the "xlswrite" I need.

However, the structure is:

    function y = fcn(u)

    y = u;

and to export to excel would imply to create a "void" fuction. It would be a correct use of this block? Which would be the syntaxis to do the "void"?

What do you think? Is there another option to avoid using "out." objects to export data to Excel?

The other path to solve this conflict would be to keep "To workspace" datas as "out." objects and export them as I was doing, by workspace postprocessing, and find another way to create the "Prueba_no_modules_out" variable in simulink other than by "To workspace" un-checking "Single simulation output".

Hope I explained well.

Thank you

- Ester

[Fangjun Jiang]

The common method is to save other variables using "To Workspace" block, save it to array and then run xlswrite() in post processing. "Single simulation out" just combines all saved variables into one structure.

[Ester Panea Murillo]

Thank you very much Fangjun for your fast responses, everithing works!!