System objects

System objects allow you to implement algorithms using MATLAB. System objects are a specialized kind of MATLAB object, designed specifically for implementing and simulating dynamic systems with inputs that change over time.

After you define a System object, you can include it in a Simulink model using a MATLAB System block.

Model Description

There are three MATLAB System blocks in this model. The first block does not have any customization for block appearance and by default shows the name of the System object on the block. The port labels for this block are obtained from the name of the arguments in thestepImplmethod of the System object. Second block shows custom text and custom port labels on the block icon. The third block shows a custom block icon image.

System Object Class Definition

You can access MATLAB source code used by the MATLAB System block by clicking the "Source Code" hyperlink from the block dialog. TheTimesTwoSystem object used in the first block has no customization and implements only thestepImplmethod. TheCustomBlockIconExampleSystem object implements the following methods for customizing block appearance.

The System object has aDisplayImageproperty to choose between text and image for display on the block.

TimesTwoSystem object

classdef TimesTwo < matlab.System %TimesTwo Multiply input by 2 % obj = TimesTwo returns a System object, obj, that % multiples its input by two. methods(Access = protected) function y = stepImpl(~, u) y = 2 * u; end end end

CustomBlockIconExampleSystem object

classdef CustomBlockIconExample < matlab.System % SystemObjectBlockIconExample Customize Block Icon properties(Nontunable) % DisplayImage Select to display image as block icon DisplayImage (1,1) logical = false end methods(Access = protected) function y = stepImpl(~, u) y = u; end function inputName = getInputNamesImpl(~) inputName = "MyIn"; end function outputName = getOutputNamesImpl(~) outputName = "MyOut"; end function icon = getIconImpl(obj) % Return text or image to be displayed on the block icon % Use array of strings to display multiple lines of text if obj.DisplayImage % Display image icon = matlab.system.display.Icon('slexngc6543aPix.jpg'); else % Display text icon = ["Block icon", "with custom text"]; end end end end