Creating delay with a while loop in Matlab

Question

As a student I am currently working on a Matlab Simulink project. I am quite new to using Matlab/Simulink (few weeks).

I want to implement and run a Matlab “.m” file with which I can open Simulink and start the simulation. The aim is to do a 24h Test with a load cell cut into 1h “pieces” and to save the data to different sheets of an excel file each hour. So my simulation runs for 1h, stops and starts again, and so on. Through Matlab and a “for” loop I do the measures 24 times. Between measuring steps I have to wait for simulink to finish its measures and saving the file in order for the Simulink window to be able to get closed by close_system('Thesis_SerDatTransm_Simulink').

So I tried to implement the delay with a while loop and by checking if the measures I get fit into an array of the size bigger than 449 (I measure 449 values):

for k=0:1:24
    % Load Simulink
    load_system('Thesis_SerDatTransm_Simulink.slx')

    % Open Simulink
    open_system('Thesis_SerDatTransm_Simulink.slx')  

    % Start Simulation
    set_param('Thesis_SerDatTransm_Simulink', 'SimulationCommand', 'Start');

    % Save Data
    my_cell = sprintf('A%d',k);
    xlswrite('file.xlsx',y,my_cell)

    % Wait for Simulation
    while 1
        test=size(y)>=449;
       if (test)
         close_system('Thesis_SerDatTransm_Simulink')
         break
       end
    end
end

The Problem now is, that program gets stuck at the while loop. Simulink is started, but no simulation or data gathering is done. So I wondered if anyone could check if something is wrong with my While loop, since the rest of the programm works all fine without the loop (but receiving an error message, that during the simulation, Simulink window can't be closed). I know there is a way to create a delay with waitforin matlab and create another function which I could call, but I couldn't figure out how to do this yet.

thanks

Regards

hohmchri

Answer 1

The right way to do this is to use the sim function to run your model (not the sequence of load_system, open_system and set_param that you have).

sim will block the execution of m-code until the model completes executing. Data can either be returned into the workspace (when used with no output arguments) or returned as an output from the call to sim. (And then you can write it to Excel as you've done.)

The only reason not to use sim, and perhaps use the commands you have, is if the model takes a long time to initialize, and you don't want to to open and close it every time through the loop. However, even in this case your code isn't correct. The load_system would be outside the loop; the open_system is not required; in your while loop you would poll the model's SimulationStatus property to see if it is still running (not the size of the y variable); and the close_system would be after the loop (as indicated by @m_power in one of the comments).