A PAS POU is a library of function blocks that have been developed by Yokogawa to facilitate the programming of control applications. These save users considerable time as the IEC61131-3 function blocks offer only the basic functions used in the IA field. (For example, advanced functions such as bump-less start have to be included in the PID block in the IA field even though the IEC function block does not have this function.) Users can easily construct the regulatory control logic and save time by combining PAS POU function blocks.