How do I modify variables in the model workspace from a Simulink block?

My Simulink block diagram has many gains whose values are variables stored in the Model Workspace.

I need to modify these gains dynamically using blocks in Simulink i.e. when a triggered subsystem is run, many of these gains have to change to new values specified by some Simulink block. I want these values to persist even after I terminate the simulation.

If this is possible, what block can do this?

Thanks.

Answer 1

[Swarooph]

Jeeven,

You can manipulate model workspace variables using MATLAB commands on a Simulink.Workspace variable. Refer to the following documentation to see how to make that happen in your particular case:

• Use MATLAB Commands to Change Workspace Data
• Describe model workspace using Simulink.ModelWorkspace

As to WHERE you would put these commands, it depends on your scenario.

1. Do these variables change only at the end of the simulation so that it can be used for the next time you start a simulation? Then you can put it in the StopFcn callback (Documentation here).
2. If the variables change EVERY time step during the simulation, try putting it in a MATLAB function block since this would execute every time step (Documentation here).

[Jeeven Hugh]

Thanks. This works, kind off. I am receiving an error when I try to use the MATLAB Function block.

In the MATLAB Function block, I am trying to read data from a .coe file using the textscan function in Matlab. My code works when it is not in Simulink i.e. just from a normal .m file; however, Simulink gives the following error:

*Simulink does not have enough information to determine output sizes for this block. ...

Function 'textscan' is not supported for code generation. Consider adding coder.extrinsic('textscan') at the top of the function to bypass code generation.*

I want to be able to generate C code from this Simulink project, so if I use that line, I will not be able to generate C code from my Simulink project. Is there any good workaround?

Thanks.

[Jeeven Hugh]

I saved my coefficients to a .mat file, and I am able to import them into Simulink; however, I still cannot change the variables in the Simulink ModelWorkspace.

How do I change the variables in the Simulink ModelWorkspace and still be able to generate C code from my Simulink block diagram?

I tried using the assignin method, but that does not support code generation.

Thanks.