How do I regulate/control S-Functions?

Hello,

I am implementing a water treatment module, microfiltration membrane, in a Level-2 Matlab S-Function. Currently I use the blocks 'SetInputPortSamplingMode', 'Outputs', and 'Derivatives'. In the beginning of Outputs I am initialising one ContState.

Right now I have the problem to regulate my system. I want to initialize a back wash process and a way to pause the treatment unit when it is not needed. I cannot figure out how to implement these.

Any help or recommendation is appreciated. Thank you in advance