Programmatic execution of Simulink (with an FMU in Simulink)

I am trying to co-simulate Simulink and another external code. Here is my manual process:

1. Run external code to generate FMU to be used in a Simulink model
2. Open the .slx file and double-click on the FMU block to the load the generated FMU from step 1
3. Run external code again to start "listening" over TCP/IP
4. Run Simulink to begin co-simulation

The manual process works fine on a single machine. However, I would like to do this all programmatically and I think steps 1, 3, and 4 should be doable using a script in Matlab. I also think the Simulation object should allow me to execute the first half of step 2. What I am unsure of is how to script the second part of step 2 i.e., load the externally generated FMU into the FMU block in Simulink.

Appreciate your thoughts in advance!

Thanks.

Answer 1

[Abhishek Kumar Singh]

Hi @IceBreakerSours,

To automate the co-simulation process between Simulink and your external code, you can use MATLAB scripting to handle all of the steps. Here's how you can achieve this:Steps to Automate:

1. Generate FMU from External Code: If your external code can be called from MATLAB, you can use the system or ! command to execute it directly from your script.
2. Load FMU into Simulink: Use MATLAB commands like set_param to programmatically set the parameters of the FMU block in your Simulink model to point to the newly generated FMU file.
3. Start External Code for Listening: Again, use the system or ! command to start your external code for listening over TCP/IP.
4. Run the Simulink Model: Use the sim command to run the Simulink model programmatically.

Here's an example MATLAB script:

% Step 1: Generate FMU using external code
system('path_to_your_external_code_to_generate_fmu');

% Step 2: Load FMU into Simulink
modelName = 'your_model_name';
fmuBlockPath = [modelName '/FMUBlockName']; % Adjust this path to your FMU block
fmuFilePath = 'path_to_generated_fmu.fmu';  % Path to the generated FMU

% Load the Simulink model and set the FMU file path param
load_system(modelName);
set_param(fmuBlockPath, 'FMUName', fmuFilePath);

% Save the changes to the model
save_system(modelName);

% Step 3: Start external code for listening
system('path_to_your_external_code_to_start_listening');

% Step 4: Run the Simulink model
simOut = sim(modelName);

% Optionally, process the simulation output
% results = simOut.get('yout'); % Adjust this according to your needs

Ensure that fmuBlockPath accurately references the FMU block in your Simulink model. Also verify that the paths to your external code and FMU file are correct and accessible from MATLAB. Do consider implementing error handling for system calls and Simulink operations to address potential issues during execution. If running across multiple machines, try MATLAB's Parallel Computing Toolbox to facilitate distributed execution.

Hope this helps!

[IceBreakerSours]

Thank you @Abhishek Kumar Singh

Right-clicking the FMU block in the .slx file (opened via Simulink), I do not see "Copy Path to Clipboard" option. However, digging into documentation on get_param, I made some incremental progress. For instance:

paths = find_system(mdl,'Type','Block') helped locate the path to FMUName.

When I execute the script, an error message pops up saying the block does not have a parameter named FMUName. When I right click the FMU block and choose Block Parameters (FMU), all I have in the text box is the FMUName.fmu.

h = getSimulinkBlockHandle(path,true) returns a floating point number that makes no sense to me. Also, get_param(h,'DialogParameters') returns a couple of parameters that contains the TCP/IP port and ip address used by the other code.

set_param needs to have at least 3 arguments but, for now, I do not have any parameters that need to be changed. I tried to specify the TCP/IP port and ip address using set_param and try to bypass the issue but the number of arguments must be odd. Once I removed fmuFilePath, the script appears to have worked. However, I haven't tested it thoroughly yet.

Now that one hurdle is crossed (fingers crossed), the next hurdle has now come up. When I execute Step 3, the command prompt doesn't appear because the other code is in "listening" mode over TCP/IP and waiting for Simulink to communicate with it. I suspect there must be a way to return control to the command prompt once the other code is in listening mode.

[Abhishek Kumar Singh]

Hi @IceBreakerSours,

Couple of points:

1. Then block or model handle is a floating point number. You have to use a function getfullname to get the path string. Refer to the screenshot below:
2. 'FMUName' is an object parameter. Here's how you can use it:
3. get_param(h,'DialogParameters') returns dialog parameters after your FMU is loaded in the block. You cannot use dialog parameters to select FMU file.
4. set_param always needs 3 or 5 or 7 arguments, first being block handle or full block path including block name, for example, 'untitled1/FMU' and parameter name-value pairs.
5. I have edited the point of getting the FMU block path interactively- thats a way to get full path of FMU file from File Explorer.
6. Regarding your next hurdle, there are two ways- if you are using bang operator(!), add an & at then end to run the command in background so that you can continue to use Command Window, for example- >>!externalProgram &. If you are using system command, use system(externalProgram &); in command window or script.

I hope this helps.

[IceBreakerSours]

Thanks again @Abhishek Kumar Singh

Step 6 from your latest response appeared to be promising until it revealed a likely flaw in my description.

Let's say I am trying to execute a Windows batch (.bat) script. While either of your suggestions will fire up a new command prompt window, they do not execute the batch script. While I can enter the command to execute the batch script in the command prompt and that works fine, I was hoping to avoid having to fully automate the process.

Another option I ran into will fire up another instance of Matlab - which, to be sure, is okay but not quite what I am hoping for.

[Abhishek Kumar Singh]

Hi @IceBreakerSours,

You can flawlessly run BAT scripts from Command Window as I mentioned in point 6.

You can have a more potent BAT file for robust execution of Step 3 of your process.

[IceBreakerSours]

Thank you @Abhishek Kumar Singh That did the trick for me.

Appreciate the generous support. I managed to execute all steps programmatically without firing up even the Matlab GUI.