Undefined identifier when using LibMdlStartCustomCode

Hi,

I'm using the function LibMdlStartCustomCode in a tlc file:

%<LibMdlStartCustomCode("aaa","trailer")>

However, I obtain the following error message at code generation:

Error: File: C:\Program Files\MATLAB\R2021b\rtw\c\tlc\mw\hookslib.tlc Line: 320 Column: 22
Undefined identifier System
Main program:
==> [00] C:\Program Files\MATLAB\R2021b\rtw\c\tlc\mw\hookslib.tlc:LibMdlStartCustomCode(320)

do anyone have an idea what is going on ?

Answer 1

[Kausthub]

Hi Stéphane,

I understand that you are facing an error while generating code using a custom TLC file which contains the “LibMdlStartCustomCode” function.

The provided error message tells us that the identifier “System” is undefined (https://www.mathworks.com/help/rtw/tlc/tlc-error-messages.html). You get this error because “System” is not part of “CompiledModel" which means that “System” is missing from your “model.rtw” file.

Some points to be noted:

• “System” is defined in the “model.rtw” file and does not require any additional assignment in the TLC file.
• Please verify whether “System” is defined in the “model.rtw" file and check whether “NumSystems” is greater than 0.
• There is one “System” for each nonvirtual subsystem in your Simulink model. So, please ensure that your model contains at least one nonvirtual subsystem.

Here are few resources that might give a better understanding of the issue:

• https://www.mathworks.com/help/ecoder/ug/introduction-to-the-model-rtw-file.html
• https://www.mathworks.com/help/rtw/tlc/build-process.html
• https://www.mathworks.com/help/rtw/ug/customizing-system-target-files.html

Hope this helps and solves your error!