Generate Code for unused Variables in Data Dictionary

is it possible to declare some variables as global inside a datadictionary and have these variables show up in a declaration file even if they are unused in the model?

Answer 1

[Abhas]

Hi @Jake Gareau,

In MATLAB, it is not directly possible to declare global variables in a data dictionary and have them appear in a declaration file if they are unused in the model. MATLAB's code generation processes exclude unused variables to optimize the generated code. However, there are workarounds:

1. Using Data Store Memory blocks: To declare such variables explicitly as global, you can create Data Store Memory blocks for them in your Simulink model. These variables will then appear in the code as global, but this requires integrating the Data Store Memory blocks within your model explicitly.
2. Simulink.Signal Objects: You can define these variables as "Simulink.Signal" objects in the base workspace or the data dictionary and mark them as "ExportedGlobal". However, if these signals are not referenced in the model, they may still not appear in the generated code. This approach is commonly used in conjunction with MATLAB Function Blocks for sharing variables across different parts of the model.

You may refer the below MathWorks documentation links to know more about the same:

1. https://www.mathworks.com/help/simulink/ug/simulink-signal-objects-matlab-function-blocks.html
2. https://www.mathworks.com/help/simulink/ug/data-store-memory-matlab-function-blocks.html

Answer 2

[Mark McBroom]

AFAIK this is not possible. One simple workaround would be to create global data stores in the model for each of these variables.

Answer 3

[Sivsankar]

Hi @Jake Gareau,

You might consider creating a MATLAB struct with all the parameters and adding that struct to the SLDD file. This approach ensures that even if only one of the variables is used by the model, all the variable values will be exported to the generated code. You can refer to the following MATLAB answer for a similar query:

https://www.mathworks.com/matlabcentral/answers/2023862-how-to-contain-all-paramters-in-one-sldd-file-when-generating-c-code-even-those-are-not-referenced?requestedDomain=

Here is a sample snippet illustrating how you can implement this workaround:

%create MATLAB struct
myParams = struct(...

     'param1',4,...

     'param2',5,...

     'param3',6);

%create bus object for the struct

Simulink.Bus.createObject(myParams)

myParamsType = slBus1;

%create Simulink parameter of the struct

myParams = Simulink.Parameter(myParams);

myParams.DataType = 'Bus: myParamsType';


%add the Simulink parameter created to the sldd file

myDictionaryObj = Simulink.data.dictionary.open('filename.sldd');

dDataSectObj = getSection(myDictionaryObj,'Design Data');

addEntry(dDataSectObj,'Params',myParams)

Now, whenever you reference at least one parameter from this MATLAB struct, the generated code will include all the variables from this struct.

Thanks.