How do I provide input to a Simulink model without placing it in the workspace

Question

I have a Simulink model that is currently being run from a script (i.e. not a function). The script writes variable values to the MATLAB workspace, runs the model simulation

Answer 1

Well I don't know how to do it from a simple function, but it's really handy to do it from inside a class function (method). It works fine with version 2009b.

Place the code in file Test.m:

classdef Test < handle
    properties
        mdl
        % Default input signal
        t = [0 1 1 2]'
        u = [0 0 1 1]'
    end

    methods
        function this = Test(mdl)   % Constructor
            this.mdl = mdl;
        end

        function sim(this)
            % Load model
            load_system(this.mdl);
            % Prepare model configuration
            conf = getActiveConfigSet(this.mdl);
            cs = conf.copy();
            set_param(cs, 'StopTime', '4');
            set_param(cs, 'LoadExternalInput', 'on');
            set_param(cs, 'ExternalInput', '[test.t test.u]');  % <-- 1
            % Run simulation
            simout = sim(this.mdl, cs);
            % Plot results
            tout = simout.find('tout');
            yout = simout.find('yout');
            plot(tout, yout(:,1), 'b--');
        end
    end
end

Then just:

>> test = Test('TestSim');
>> test.sim();

What happens? You create object test, that has defined fields t and u. Then in method sim() You say to Simulink to look for input '[test.t test.u]'. Both Simulink and the method sim() has access to this variables (I believe this is the most important thing).

OK it still has a big drawback that is marked with number 1. You have to know explicitly how a reference to class instance will be named in the workspace ('test' in this case). You can work it around by passing the name in a constructor, or you can use static variables and methods, but this way won't allow you to change input signal dynamically.