Why do the parameters of the TcCOM instance not always change after a "Reload TMC/TMI" operation?

Observation:

TwinCAT 3 contains an existing instance of a TcCOM object.
As already explained, the model parameters, e.g. the parameters of a PID controller, can be modified in TwinCAT via the exported block diagram or via the Parameter (init) tab of the TcCOM object outside of Simulink. If you change your Simulink model in Simulink and create a new TcCOM object, you can, of course, update this via the call reload TMC/TMI by right-clicking on the corresponding TcCOM object in TwinCAT. In this case all links are preserved, as long as the process image remains unchanged.

A distinction is made between two different cases

Only model parameters were modified in Simulink, e.g. PID control parameters
Model parameters were modified, and further structural changes were made in the model

In the former case you will note that the parameters of your TcCOM object have not changed after the call Reload TMC/TMI. The startup values are taken from the previous TcCOM instance, so that your settings from TwinCAT for this module instance are not lost. To load the model parameters from Simulink, you can select them by navigating to the ModelParameters dropdown menu in the right part of the block diagram window: right-click on Startup value or Prepared and select Insert default value. The default values are loaded from the TMC file, so that the parameter settings are taken from Simulink.

Why do the parameters of the TcCOM instance not always change after a "Reload TMC/TMI" operation? 1:

Alternatively, you can delete the old TcCOM object and insert the new TcCOM object. In this case all previous model parameters are lost, and the newly added object has the same model parameters as the corresponding Simulink model.

If additional changes were made apart from the model parameters, the model code also changes, which means retention of the previous model parameters settings is only possible to a limited degree. In this case the TwinCAT module parameters from the previous instance are retained, and the System Manager is still able to assign them unambiguously.