TABLE OF CONTENTS Automation does not end with equipment control; it also includes higher levels of control that manage personnel, equipment, and materials across production areas. Effectiveness in manufacturing companies is not based solely on equipment control capability. Manufacturing companies must also be efficient at coordinating and controlling personnel, materials, and equipment across different control systems in order to reach their maximum potential. This is usually accomplished using software systems and documented procedures that are collectively called the "manufacturing execution system (MES)" layer. MES defines a diverse set of functions that operate above automation control systems, reside below the level of enterprise business systems, and are local to a site or area. This chapter explains the functions of the MES layer and how these functions integrate with other corporate business systems.
The ANSI/ISA-95.00.03 2005 Enterprise-Control System Integration, Part 3: Models of Manufacturing Operations Management standard defines 5 levels of activities in a manufacturing organization. Automation and control supports one level and MES supports a higher level, as shown in Figure 25-1.
Level 0 defines the actual physical processes.
Level 1 defines the activities involved in sensing and manipulating the physical processes. Level 1 elements are the sensors and actuators attached to the control functions in automation systems.
Level 2 defines the activities of monitoring and controlling the physical processes and in automated systems this includes equipment control and equipment monitoring. Level 2 automation and control systems have real-time responses measured in subseconds and are typically...
