The aim of this thesis project was to develop a new control unit for basis weight valves. These valves are used in the paper industry to regulate flow of paper-pulp to the machine. The work was conducted at Peab Process AB, who mainly supplies and maintains valves in industries throughout the world. The reason for the development of a new control unit is to obtain a more precise control of the valve. Another objective is to make the product more versatile by making it possible to use several interfaces for transmission of the control singnal. The improvement of accuracy and interface implementation has brought a number of problems, which has to be solved. The results from this work consist of initial tests concerning compensation for torsion, also called shaft windup. There are also some initial results from tests regarding a regulator used for reducing errors, which are associated with absolute positioning without feedback. A large piece of the report consists of derivations and theories used to reach these results. The rest of the report has brief descriptions of the solutions made to implement signal-interfaces and vital software.