Pneumatic control valves are employed in chemical engineering for regulating liquid and gaseous media. In order to achieve a constantly high level of process reliability, the flow rate must be controlled exactly. A slide is driven pneumatically, changing the opening
for the flow. An inductive displacement sensor, which measures the slide position, is joined to the slide. A microcontroller handles the control and evaluation of the displacement sensor along with the closed-loop control, parameterisation and bus linkage of the control valve. Due to the already existing controller, the position measurement is realised for practically no cost, apart from a few passive components.