Closed Loop with optimisiation problem

I would like to do a closed loop simulation with a FMU block and solving a optimisation problem.

1. Solve a optimisations problem, call cplex solver from a Matlab M-file 2. Hold the signal constant for T=…min (solution optimisation), and give it as a input for the FMU block 3. Take the output from FMU block and solve the next Optimisation problem

My question is, is a Matlab function the right way to do that? Of course, the system on the attacked picture does not work, because the optimisations problem is called every solver time step…

Does anyone know how to fix that easily, or must I do it completely different ?

(Called MPC, but I can’ t use the MPC block in matlab)