Group Multiple Model Arguments into a Single Structure

This example shows how to programmatically configure multiple instances of a referenced model to use different values for the same block parameter by using structures.

Configure Referenced Model to Use Model Arguments Grouped into Structure

You can use structures to reduce the effort of maintenance when you want to add, rename, or delete arguments. With structures, the mathematical functionality of the models is the same.

To replace the parameter values with structures for ex_model_arg_ref and ex_model_arg, follow these steps.

Open model ex_model_arg_ref. This model represents a reusable algorithm.

open_system('ex_model_arg_ref')

Create a structure that contains one field for each of the parameter objects that exist in the ex_model_arg_ref workspace. Specify a value for each field.

structForInst1.gain = 3.17;
structForInst1.coeff = 1.05;

Store the structure in a Simulink.Parameter object.

structForInst1Param = Simulink.Parameter(structForInst1);

Copy the Simulink.Parameter object into the ex_model_arg_ref model workspace. For this example, name the copy of the object structArg.

modelWorkspace = get_param('ex_model_arg_ref','ModelWorkspace');
assignin(modelWorkspace,'structArg',copy(structForInst1Param));

Configure structArg as the only model argument.

set_param('ex_model_arg_ref','ParameterArgumentNames','structArg')

In the ex_model_arg_ref model, set the Gain parameter of the Gain block to structArg.gain and set the Numerator parameter of the Discrete Filter block to structArg.coeff.

set_param('ex_model_arg_ref/Gain','Gain','structArg.gain')
set_param('ex_model_arg_ref/Discrete Filter',...
    'Numerator','structArg.coeff')

Copy the existing structure as structForInst2Param.

structForInst2Param = copy(structForInst1Param);

Set the field values in the two structures to the same numbers that you used to set the model argument values in the Model blocks.

structForInst1Param.Value.coeff = 0.98;
structForInst1Param.Value.gain = 2.98;
structForInst2Param.Value.coeff = 1.11;
structForInst2Param.Value.gain = 3.34;

Open model ex_model_arg. This model represents a system model that uses multiple instances of the reusable algorithm.

open_system('ex_model_arg')

For model instance Model, set structArg to structForInst1Param. For model instance Model1, set structArg to structForInst2Param.

instSpecParamsStruct = get_param('ex_model_arg/Model','InstanceParameters');
instSpecParamsStruct1 = get_param('ex_model_arg/Model1','InstanceParameters');

instSpecParamsStruct(1).Value = 'structForInst1Param';
instSpecParamsStruct1(1).Value = 'structForInst2Param';

set_param('ex_model_arg/Model','InstanceParameters',instSpecParamsStruct);
set_param('ex_model_arg/Model1','InstanceParameters',instSpecParamsStruct1);

Use Bus Object as Data Type of Structures

You can use a Simulink.Bus object as the data type of the structures. The bus object makes sure that the characteristics of the instance-specific structures, such as the names and order of fields, match the characteristics of the structure in the model workspace.

To set the data type of the structures to bus objects, follow these steps.

Use the Simulink.Bus.createObject function to create the bus object. The hierarchy of elements in the object matches the hierarchy of the structure fields. The default name of the object is slBus1.

Simulink.Bus.createObject(structForInst1Param.Value);

Rename the bus object by copying it.

myParamStructType = copy(slBus1);

Set the data type of the parameter objects in the base workspace by using the bus object.

structForInst1Param.DataType = 'Bus: myParamStructType';
structForInst2Param.DataType = 'Bus: myParamStructType';

For the structArg object, set DataType to Bus: myParamStructType.

temp = getVariable(modelWorkspace,'structArg');
temp = copy(temp);
temp.DataType = 'Bus: myParamStructType';
assignin(modelWorkspace,'structArg',copy(temp));
close_system('ex_model_arg_ref',0)
close_system('ex_model_arg',0)

Related Topics

• Parameterize a Referenced Model Programmatically