Parameterizing Composite Components

Composite component parameters let you adjust the desired parameters of the underlying member components from the top-level block dialog box when building and simulating a model.

Specify the composite component parameters by declaring a corresponding parameter in the top-level parameters declaration block, and then assigning it to the desired parameter of a member component. The declaration syntax is the same as described in Declare Component Parameters.

For example, the following code includes a Foundation library Resistor block in your custom component file, with the ability to control the resistance at the top level and a default resistance of 10 Ohm:

component MyCompositeModel
[...]
  parameters
     p1 = {10, 'Ohm'};
     [...]
  end
  components(ExternalAccess=observe)
     r1 = foundation.electrical.elements.resistor(R = p1);
     [...]
  end
[...]
end

You do not have to assign all the parameters of member blocks to top-level parameters. If a member block parameter does not have a corresponding top-level parameter, the composite model uses the default value of this parameter, specified in the member component.

Caution on Using `setup` to Parameterize Composite Components

You can establish the connection of a top-level parameter with a member component parameter either in the components declaration block, or later, in the setup section. Starting in R2019a, using setup is not recommended. If you have legacy code using the setup function, update it to use parameter assignment in the components block instead. For example, this code is equivalent to the example above:

component MyCompositeModel
[...]
  parameters
     p1 = {10, 'Ohm'};
     [...]
  end
  components(ExternalAccess=observe)
     r1 = foundation.electrical.elements.resistor;
     ...
  end
   [...]
   function setup
      r1.R = p1;
   end
   [...]
end

Note

In case of conflict, assignments in the setup section override those made in the declaration section.

Components are instantiated using default parameter values in the declaration section before setup is run. Therefore, if you make adjustments to the parameters in the setup section, use a subsequent setup section assignment to establish proper connection between the top-level parameter with a member component parameter, as shown in the following example:

component RC
  nodes
    p = foundation.electrical.electrical; % :right
    n = foundation.electrical.electrical; % :left
  end
  parameters
    R = {1 , 'Ohm'}; % Resistance
    tc = {1 , 's'};  % RC time constant
  end
  parameters(ExternalAccess=observe)
    C = {1 , 'F'};
  end
  components(ExternalAccess=observe)
    c1 = foundation.electrical.elements.capacitor(c=C);
    r1 = foundation.electrical.elements.resistor(R=R);
  end
  function setup
    C = tc/R;
    c1.c = C; % This assignment ensures correct operation
  end
  connections
    connect(c1.p, p);
    connect(c1.n, r1.p);
    connect(r1.n, n);
  end
end

Related Examples

Composite Component — DC Motor