# Manufacturing Execution System (MES)

Operations · `MES` · verification: source checked

A manufacturing execution system is the Level 3 layer in the ISA-95 model, where it manages manufacturing operations. It sits between the Level 2 monitoring and supervisory control devices, such as PLCs and DCSs, and the Level 4 business planning and logistics systems, such as ERP. ISA-95 primarily defines the interface between levels 3 and 4.

## Specification

| Property | Value |
|---|---|
| Kind | system |
| Origin | ISA-95 (ANSI/ISA-95, IEC 62264), Level 3 of the five-level model |

## Study notes

- ISA-95 is also published as ANSI/ISA-95 and adopted as IEC 62264.
- The ISA-95 model has five levels, 0 to 4, and is based on the Purdue Reference Model for computer-integrated manufacturing.
- Level 0 covers the physical production processes: machinery and other assets in the field or on the floor.
- Level 1 covers sensors, smart devices and valves that sense or affect production.
- Level 2 covers monitoring and supervisory control, including programmable logic controllers (PLCs) and distributed control systems (DCSs).
- Level 3 also includes supervisory control and data acquisition (SCADA) systems alongside MES.
- Level 4 covers business planning and logistics activities, including enterprise resource planning (ERP) systems.
- ISA-95 was established in the mid-1990s and is technology-agnostic, prioritising activities rather than technologies.
- The ISA95 committee oversees creation of the standards, aiming to define an abstract model of the enterprise and common terminology.

## Sources

1. [Manufacturing Execution System (MES) - Glossary | CSRC](https://csrc.nist.gov/glossary/term/manufacturing_execution_system) (accessed 2026-10-25)
2. [ISA-95 Standard: Enterprise-Control System Integration](https://www.isa.org/standards-and-publications/isa-standards/isa-95-standard) (accessed 2026-10-25)

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