The Fixed-Point Tool displays the subsystems that are in graphical masked subsystems, but does not display subsystems that are in functional masked subsystems. This is a known limitation in MATLAB releases up-to MATLAB R2009b,
A functional masked subsystem has its own mask workspace and mask parameters. A graphical masked subsystem has no mask workspace or mask parameters. By design, the Fixed-Point Tool does not allow you to control the Data Type Override or Fixed-Point Instrumentation Mode settings on subsystems under a functional masked subsystem.
In R2009b and earlier versions of the Fixed-Point Tool, this might not be clear if you:
Launch the Fixed-Point Tool with a model that has a graphical masked subsystem.
Convert the graphical masked subsystem to a functional masked subsystem.
Save and close the modified model.
Re-launch the Fixed-Point Tool with the saved model.
The Fixed-Point Tool does not update the tree hierarchy, Data Type Override, or Fixed-point Instrumentation Mode settings after conversion to a functional masked subsystem. This gives the impression that you can still set Data Type Override and Fixed-point Instrumentation Mode settings for subsystems under the functional masked subsystem. However, after you save and close the model and then re-launch the Fixed-Point Tool with the saved model, the subsystems under the functional masked subsystem are no longer accessible.
In R2010a, if you have the Fixed-Point Tool open and you convert a graphical masked subsystem in the model to a functional masked subsystem, the Data Type Override and Fixed-point Instrumentation Mode settings for subsystems under the functional mask are disabled after the dialog is refreshed by selecting a different tree node and then re-selecting the subsystem.
