Process automation system

A process control or automation system is used to automaticly control a process such as chemical, oil refinerys, paper and pulp factories. The PAS often uses a network to interconnect sensors, controllers, operator terminals and actuators. A PAS is often based on open standards in contrast to a DCS (distributed control system), which is traditionally proprietary. However in resent times the PAS is considerd to be more assosiated with SCADA systems.

PAS is the lowest level of automation, while MES are considered to be directly positioned above a PAS