Case Histories Turbomachines performances control is strictly depending from the interactions between the system control logic and devices dynamic (i.e. valves, drivers, actuators, etc...) which can act or promote modification of main fluid systems parameters over all working conditions. In order to seamlessly link the physical behavior of the system components, the functional instructions must be properly exchanged through the same language. This is possible describing the real components evolution with a system of equations that control logic can understand. Manageable inputoutput relations are often achieved from simplification and most of them are usually taken as they are, without any possibility of improvements. Approximations errors are inherited from previous applications and because of these, many situations arise where machine do not work as expected with the need of fine tuning in the field. In the worst scenario errors propagation in transient run may cause system response drift which cannot be recovered, with unknown consequences. System Control logic enhancements through Fluid-Mechanical valve dynamic transfer functions