Modeling feedback-control-circuits with DSP-builder

Hello everybody,

I work on a feasability study for FPGA-application with "model-based-design" in Matlab/Simulink.

First of all I want to implement a simple PID-controller for controlling two proportional valves via PWM. Perhaps I want to compare the parallel implementation with the implementation using a softcore like NIOS II.

Has anybody gained some experience with implementing classic feeback-control-circuits with the DSP-builder ? What are the limitations in comparison with creating models for sequential hardware structures ? Is it necessary to use manual-vhdl-code for peripheral-devices like ADC's or can the code also be generated with the DSP builder ?

Thank you in anticipation !