Explanation of SetInputPortSamplingMode Level 2 S-function callback.

Hello,

I'm writing a Level 2 Matlab S-function. I am trying to have 3 inputs and 2 outputs. It works fine with 1 output, but when I add the second output, I get the following error in Simulink:

Level-2 MATLAB S-function 'scene2latlongalt' in 'WorldSim/Level-2 MATLAB S-Function' does not have a 'SetInputPortSamplingMode' method. When a Level-2 MATLAB S-function with multiple output ports has dynamic sampling mode setting for any of its ports, it is necessary to register a 'SetInputPortSamplingMode' method

I've looked online for guidance here, and found the following links:

https://www.mathworks.com/support/search.html/answers/54276-more-than-one-output-for-level-2-s-function.html?fq[]=asset_type_name:answer&fq[]=category:simulink/sources&page=1

https://www.mathworks.com/support/search.html/answers/60102-set-ports-properties-from-level2-m-file.html?fq[]=asset_type_name:answer&fq[]=category:simulink/sources&page=1

https://www.mathworks.com/support/search.html/answers/565445-level-2-s-function-block-port-sampling-mode-error.html?fq[]=asset_type_name:answer&fq[]=category:simulink/initialize-reset-and-terminate-functions&page=1

The msfuntmpl.m sample script has an example of the SetInputPortSamplingMode callback usage, and I just modeled mine off that. However, I can't find any documentation of what the SetInputPortSamplingMode callback is actually doing. I got the code to work, but I don't really know why it works. I was hoping someone could help explain what is going on here.

I also attached the s-function .m file. It is a little bit messy, but the important parts are that I have 3 input ports, 2 output ports, and the callback function SetInputSampMode(block, idx, fd)

Thanks,

-Ryley