Simulink: Mask parameter fails to bind to block port

I'm currently working with a MATLAB Function block inside of Simulink, and I'd like to expose one of the function's arguments as a parameter in the Simulink UI. A mask seems to be the usual way of doing this, but upon adding a mask, it doesn't "bind" to the underlying block's port, as I would have expected.

Is this normal? If not, how might I go about troubleshooting this? If so, how can I prevent later users from connecting normal Simulink signals to the exposed port?

For reference, here are my mask parameters, as well as the underlying block (with the masked port exposed):

[Fangjun Jiang]

I am not following. "expose one of the function's arguments", what argument? what do you mean by "expose"?

[Lucas Ritzdorf]

The underlying MATLAB function has an argument (which appears as a port on the Simulink block) that specifies how many outputs it should produce. In the screenshot above, this is 24 — and for now, that's a hard-coded value inside the function. However, I'd actually like it to appear as a mask parameter, in the configuration parameters dialog that most standard Simulink blocks provide when double-clicked.

Answer 1

[Fangjun Jiang]

1. It is more involved for this task. I hope the attached model (in R2022b) make it easier.
2. In your model, the two inports are called input arguments, the two outports are called output arguments.
3. You need to make "num_outputs" as a "parameter data", not "input data".
4. You need to make "output" variable size and specify the max value as 24.
5. Make a mask and pass down the value for "num_outputs"
6. Run simulation and you will see 5 elements are non-zoro. Double click the masked MATLAB Function block, change the value from 5 to 3 to see the output display.

[Lucas Ritzdorf]

Perfect, thanks! That makes a lot more sense, and has made port binding work the way I'd expect.

Also, a note for anyone who might come across this later: if you need a parameter like this to be constant throughout the simulation (especially for code-generation purposes), be sure to un-check the "tunable" option for the parameter, which is found in the Model Explorer.