Control System Simulation The simulation of instrumentation control systems includes measuring or detecting devices, the controllers, and the actuating or manipulating output elements. Most measuring devices may be simulated by one or more simple lags for dynamic representation, with added nonlinearities for device characteristics, sensitivity, or operating point modeling. For special functions, such as logarithmic input–output relationships (such as pH measurements), the general-purpose function-generating units may be used or the functions generated by implicit techniques. the measuring device puts out a discontinuous (pulse-type) signal, signal-generating circuits may be used, as discussed later in this section.