How to relate between popup parameter in subsystem and switch case in matlab function?

switch HE_Type     %(which HE_Type has 2 only choices  parallel_flow or counter_flow)     
case   'parallel_flow'  
        E = (1-exp(-NTU*(1+C)))/(1+C)
        
case   'counter_flow'
        E =(1-exp(-NTU*(1+C)))/((1-C*exp(-NTU*(1-C))))    
end

% i make a model simulink to calculate the temperature of heat exchanger 
%so there is 2 types of heat exchanger so for each type there is own equation
%so i wanna to make a popup parameter in mask of subsystm (types) and relate this popup with switch case in matlab function

[Geoff Hayes]

@Mostafa Kamel - please clarify what you mean by popup.

[Walter Roberson]

How is HE_Type defined?

Are you using Guide or App Designer?

[Mostafa Kamel]

[Mostafa Kamel]

@Geoff Hayes

@Walter Roberson

i make a model simulink to calculate the temperature of heat exchanger

so there is 2 types of heat exchanger so for each type there is own equation

so i wanna to make a popup parameter in mask of subsystm (types) and relate this popup with switch case in matlab function

Answer 1

[Fangjun Jiang]

Best way for this is to use "Variant Subsystem". See document and example

There is no need to add mask anymore, although you can still add mask to select the variant if you prefer.

https://www.mathworks.com/help/simulink/slref/variantsubsystemvariantmodel.html

Second option is to use that popup in mask to control the value of a String Constant block in Simulink. That Constant block is fed as an input (the "HE_Type" input) of your MATLAB function block. Then everything is linked together.

[Mostafa Kamel]

more explaination for the second option ,please ??

@Fangjun Jiang

[Fangjun Jiang]

The second option is just like any ordinary mask. You have a variable (for the value of the String Constant block) inside the subsystem. You bring it to the mask dialog. Based on the popuo option, the value of that String Constant block will change. Then inside your MATLAB Function, you read that String Constnat value (through input port) and use it in the switch-case statment.