How can I use a variable-size coefficient vector for a discrete FIR filter in a protected model?

I am using a Discrete FIR Filter block in a protected model. I want to make the filter accept a variable-size coefficient vector. I can make the coefficient vector tunable using the function "Simulink.ModelReference.protect":

https://www.mathworks.com/help/rtw/ref/simulink.modelreference.protect.html#mw_55b8df92-a122-4c93-ad9a-6068f222c3ca

However, this does not allow me to tune the length of the coefficient vector. Is there a way to tune the length of it in a protected model?

Answer 1

[MathWorks Support Team]

Using a variable-size tunable parameter is not supported in a protected model. However, there is a workaround available if the length of the vector can be constrained. By leveraging the mathematical properties of the filter, we can employ zero-padding for the vector.

Consider a protected model that includes a Discrete FIR Filter with a coefficient vector length of 5. In this scenario, the filter can effectively accommodate a coefficient vector with a length less than 5. For instance, providing the vector [0.2, 0.3, 0, 0, 0] is equivalent to providing [0.2, 0.3] since the zeros have no impact on the filter's operation.