ISA-95 levels

ISA-95 levels are the functional levels used to describe how manufacturing processes, control systems, operations systems, and business systems relate to each other. They are commonly used when discussing integration between shop-floor equipment, MES, ERP, quality systems, and other manufacturing applications.

In the ISA-95 model, the levels are typically described as:

• Level 0: the physical production process.
• Level 1: sensing and manipulating the process, such as sensors, actuators, and basic device interaction.
• Level 2: monitoring and control, such as PLC, SCADA, DCS, or HMI functions.
• Level 3: manufacturing operations management, often including MES, dispatching, production tracking, quality execution, and maintenance coordination.
• Level 4: business planning and logistics, such as ERP, scheduling, procurement, inventory planning, and financial functions.

The levels help define system responsibilities and data exchange boundaries. For example, an MES at Level 3 may receive production orders from an ERP at Level 4 and send instructions or status information to control systems at Level 2.

ISA-95 levels should not be treated as certification levels, maturity levels, or strict network security zones. They are functional groupings. In practice, they are often compared with the Purdue model, but the two are not identical in purpose: ISA-95 focuses on enterprise-control integration and operations information models, while Purdue-style diagrams are often used to discuss industrial architecture and segmentation.