Implementation of simulink model using a .m script

Hi @Divyashree ,

Please see my response to your comments below.

Size computation for 'processed_data' failed. Unknown var 'N' used in size definition.Size computation for 'processed_data' failed. Unknown var 'N' used in size definition. In the from spreadsheet model there is no changes, the file name, sheet name, range and the output datatype is same as I've mentioned before and connected all the 38 signals of the spreadsheet to a bus creator. Also in the workspace model there are no changes. I made few modifications in the simulink model. I've implemented a .m script for the bus creator and the block parameter I've mentioned it as outputdatatype: Bus:MyBusType, mode: bus object, MyBusType. The .m script I've mentioned below. The reason I've created this object code is

defineBusObject.m
% Create the bus object
busElements(38) = Simulink.BusElement; 
% Preallocation for 38 elements

% Define each element in the bus
for i = 1:38
  busElements(i).Name = ['Signal' num2str(i)];
  busElements(i).Dimensions = 1;
  busElements(i).DataType = 'double';
end

% Assign to MyBusType
MyBusType = Simulink.Bus;
MyBusType.Elements = busElements;

% Save MyBusType in the base workspace
assignin('base', 'MyBusType', MyBusType);

After running the above object code, MyBusType will be in the base workspace.Before running the model, I executed the above script and made few modifications in the simulink model properties, that is Callback -> either in pre-loadfcn/InitFcn -> defineBusObject. After making this changes, I executed the model and I'm facing the above error.

Comments: Ensure that the variable N is defined in the MATLAB base workspace before running the Simulink model. You can do this by executing the following command in the MATLAB Command Window:

   N = 38; % or whatever value is appropriate for your model

Your script for creating the bus object appears to be correct. However, ensure that the bus object is indeed being created and assigned to the base workspace before the model runs. You can verify this by checking the base workspace:

evalin('base', 'whos') 
% This will list all variables in the base workspace

You mentioned using the InitFcn or PreLoadFcn callbacks to run the defineBusObject.m script. Ensure that these callbacks are correctly set up in the model properties. You can check this by right-clicking on the model background, selecting "Model Properties," and navigating to the "Callbacks" tab. Ensure that the script is correctly referenced:

defineBusObject

I've attached the snapshot of the model and the port and data manager. Also let me know should I need to make any changes in the ports and data manager of the matlab function. And also, Why am I geeting 1,1,1,1,1,1.... between the spreadsheet and buscreator model and '?' between bus creator and matlab function and workspace model.

Comments: If you are seeing unexpected values (like 1,1,1,1,1,1...) between the spreadsheet and the bus creator, it may indicate that the data is being interpreted incorrectly. Ensure that the data types in the Ports and Data Manager are consistent with what you expect. You can access the Ports and Data Manager by right-clicking on the bus creator block and selecting "Block Parameters." Check the data types and dimensions of the signals connected to the bus creator. To further debug the model, consider using the Simulink Debugger. You can set breakpoints in your model to inspect the values of variables at different points in the execution. This can help you identify where the unexpected values are being introduced. For reference, please click the link below.

https://www.mathworks.com/help/simulink/simulation-stepper.html

Regarding your issue with handling ‘?’ Between blocks, the ? symbol typically indicates a mismatch in data types or dimensions between connected blocks. Ensure that the output data type of the bus creator matches the expected input data type of the subsequent MATLAB function block. You can do this by checking the block parameters and ensuring that the data types are compatible. Can you please let me know, which data type is better to use? Double or string? Because it contains both alpha numeric characters. I've attached the snaps below.

Comments: Regarding your question about data types, if your data contains both alphanumeric characters, it is advisable to use a string data type. In MATLAB, you can use the string or char data types depending on your requirements. For example:

   myData = "Sample123"; % Using string data type

Hope this helps.