How do I create a sample time independent S-function block from a subsystem in Simulink Coder 8.4 (R2013a)?

I am generating an S-function block from a subsystem by right-clicking on the subsystem block and selecting "C/C++ Code > Generate S-Function...". I notice that the generated S-function code has the sample times hardcoded in it. So when I try to use this new block in different models, they fail to run. I would like to know how I can make S-function block independent of the sample time.

Answer 1

[MathWorks Support Team]

It is mentioned in the help documentation under "Simulink Coder > Customization > Block Authoring > S-Functions > Create S-Function Blocks from a Subsystem" that when creating an S-Function Block from a Subsystem, the block will have the sample times hard-wired. However, if the model has no dependence on the sample time, then you can generate an S-function which is independent of the sample time. The section under "Sample Time Propagation in Generated S-Functions" mentions the conditions that govern sample time propagation for S-functions. Also take a look at the referenced pages "Inherit Sample Times".

The sample model, sampleModel_R2013a.slx, illustrates this behavior. The model is independent of sample time and the "Periodic sample time constraint" property (Configuration Parameters > Solver > Tasking and sample time options) is set to "Ensure sample time independent". Now the S-function block generated will be sample time independent. You will also notice in the generated code, SourceSubsys_sf.c, that mdlInitializeSampleTimes() specifies ssSetSampleTime(S, 0, INHERITED_SAMPLE_TIME);