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Programmatically Initialize Arrays of Buses

This example shows how to initialize an array of buses. Suppose that you define Simulink.Bus objects named MyData and PressureBus.

% Bus object: MyData 
clear elems;
elems(1) = Simulink.BusElement;
elems(1).Name = 'temperature';
elems(1).DataType = 'int16';

elems(2) = Simulink.BusElement;
elems(2).Name = 'pressure';
elems(2).DataType = 'Bus: PressureBus';

MyData = Simulink.Bus;
MyData.Elements = elems;

% Bus object: PressureBus 
clear elems;
elems(1) = Simulink.BusElement;
elems(1).Name = 's1';

elems(2) = Simulink.BusElement;
elems(2).Name = 's2';

PressureBus = Simulink.Bus;
PressureBus.Elements = elems;
clear elems;

The object named MyData has two elements, named temperature and pressure. The pressure element uses Bus object PressureBus, which has two elements, named s1 and s2.

The data type of temperature is int16, and the data types of s1 and s2 are double.

To specify initial conditions for an array of buses, create a variable whose value is an array of initial condition structures.

initValues(1).temperature = int16(5);
initValues(1).pressure.s1 = 9.87;
initValues(1).pressure.s2 = 8.71;

initValues(2).temperature = int16(20);
initValues(2).pressure.s1 = 10.21;
initValues(2).pressure.s2 = 9.56;

initValues(3).temperature = int16(35);
initValues(3).pressure.s1 = 8.98;
initValues(3).pressure.s2 = 9.17;

The variable initValues provides initial conditions for an array of three buses. You can use initValues to specify the Initial condition parameter of a block such as a Unit Delay block.

Alternatively, you can use a scalar structure to specify the same initial conditions for all the buses in the array.

initStruct.temperature = int16(15);
initStruct.pressure.s1 = 10.32;
initStruct.pressure.s2 = 9.46;

If you specify initStruct in the Initial condition parameter of a block, each bus in the array uses the same initial value, 15, for the signal element temperature. Similarly, the buses use the initial value 10.32 for the element pressure.s1 and the value 9.46 for the element pressure.s2.

To create an array of structures for a bus that uses a large hierarchy of signal elements, consider using the Simulink.Bus.createMATLABStruct function.

Suppose pressure represents a nested array of buses with dimensions [1 3]. To programmatically set this value, access the Dimensions property of the second element of the Elements property of the MyData object.

MyData.Elements(2).Dimensions = '[1 3]';

Create an array of four initialization structures by using the function Simulink.Bus.createMATLABStruct. Store the array in the variable initStruct. Initialize all the individual signals to the ground value, 0.

initStruct = Simulink.Bus.createMATLABStruct('MyData',[],[1 4])
initStruct = 

  1×4 struct array with fields:

    temperature
    pressure

Inspect the created structure.

  1. In the base workspace, double-click the variable initStruct to view it in the variable editor.

    The four structures in the array each have the fields temperature and pressure.

  2. To inspect a pressure, double-click one of the fields.

    The value of each of the four pressure fields is an array of three substructures. Each substructure has the fields s1 and s2.

To provide unique initialization values for the signals in an array of buses, you can interactively specify the values using the variable editor.

Alternatively, you can programmatically specify the values. For example, to assign value of 15.35 to the field s1 of the second substructure pressure in the third structure of initStruct, enter:

initStruct(3).pressure(2).s1 = 15.35;