“On the one hand, an ERP system promises -by the force of its title- to link the entire enterprise together in a comprehensive resource plan. However, ERP systems in real life are far less ambitious. They are equivalent to software to automate a firm’s accounting and administrative systems. This narrowness of outlook has greatly hindered the vital overlap between a firms’ ERP system and the system governing the automation of its production planning and execution functions. The latter system is the firm’s manufacturing execution system (MES).” Meyer H., Franz F., Thiel K., (2009) Manufacturing Execution Systems (MES): Optimal Design, Planning, and Deployment
Manufacturing execution systems (MES) are computerized systems used in manufacturing to track and document the transformation of raw materials to finished goods. MES provides information that helps manufacturing decision-makers understand how current conditions on the plant floor can be optimized to improve production output. MES works as real-time monitoring system to enable the control of multiple elements of the production process (e.g. inputs, personnel, machines and support services).
MES may operate across multiple function areas, for example management of product definitions across the product life-cycle, resource scheduling, order execution and dispatch, production analysis and downtime management for overall equipment effectiveness (OEE), product quality, or materials track and trace. MES creates the "as-built" record, capturing the data, processes and outcomes of the manufacturing process. This can be especially important in regulated industries, such as food and beverage or pharmaceutical, where documentation and proof of processes, events and actions may be required.
The idea of MES might be seen as an intermediate step between, on the one hand, an enterprise resource planning (ERP) system, and a supervisory control and data acquisition (SCADA) or process control system on the other; although historically, exact boundaries have fluctuated. Industry groups such as MESA International - Manufacturing Enterprise Solutions Association - were created in the early 1990s to address the complexity, and advise on the execution of MES Systems.