A)
In the setup function of your MATLAB S-Function, you need to configure port properties to be inherited or dynamic:
>> block.SetPreCompInpPortInfoToDynamic;>> block.SetPreCompOutPortInfoToDynamic;
You can then override the only properties that you known, as for example:
>> block.InputPort(1).DatatypeID = 0;>> block.InputPort(1).Complexity = 'Real';>> block.InputPort(1).DirectFeedthrough = true;
>> block.OutputPort(1).DatatypeID = 0;>> block.OutputPort(1).Complexity = 'Real';>> block.OutputPort(2).Dimensions = 1;>> block.OutputPort(2).DatatypeID = 0;>> block.OutputPort(2).Complexity = 'Real';
Note how the field 'Dimensions' has not been set for InputPort(1) and OutputPort(1).
B)
Similar to A), but the required input and output ports need to be configured so that they can handle variable-size signals:
>> block.InputPort(1).DimensionsMode = 'Variable';>> block.OutputPort(1).DimensionsMode = 'Variable';
In addition, in the Outputs function, you need to set the current dimensions of the output port:
>> block.OutputPort(1).CurrentDimensions = block.InputPort(1).CurrentDimensions;
For further details, please refer to the attached files:
A) matlabSfunUnknownSize.m and simpleTestMsfUnknownSize.slx
B) matlabSfunVarSize.m and simpleTestMsfVarSize.slx
and simulate the models step-by-step.
For more information on:
- how to write your own Level-2 MATLAB S-Function: https://uk.mathworks.com/help/simulink/sfg/writing-level-2-matlab-s-functions.html
- variable-size signals: https://uk.mathworks.com/help/simulink/ug/variable-size-signal-basics.html
- MATLAB and C S-Functions with variable-size signals: https://www.mathworks.com/help/simulink/ug/simulink-models-using-variable-size-signals-demos-modeling-features-variable-size-signals-or-type-varsizedemos.html
