MESA-11

MESA-11 is the functional model of the Manufacturing Enterprise Solutions Association (MESA), published in the mid-1990s. It defines 11 core functions of a Manufacturing Execution System and answers the fundamental question: what should a MES do?

In contrast, ISA-95 primarily defines how systems and layers (ERP, MES, controls) are technically coupled. MESA-11 and ISA-95 were later merged in the ANSI/ISA-95 standard, where MES sits at Level 3 between ERP (Level 4) and SCADA/controls (Levels 0–2).

The 11 Core Functions According to MESA-11

1. Operations / Detail Scheduling (ODS): Detailed scheduling of orders on lines and machines – sequencing, lot sizes, changeover logic.

2. Resource Allocation & Status (RAS): Real-time tracking of availability and status of machines, tools, materials, and personnel.

3. Dispatching Production Units (DPU): Managing the flow of orders and materials based on current planning and shop floor conditions.

4. Document Control (DOC): Managing and distributing work instructions, drawings, specifications, and checklists on the shop floor.

5. Data Collection / Acquisition (DCA): Capturing quantities, times, machine states, and process values – the foundation for OEE, traceability, and analytics.

6. Labour Management (LM): Assigning staff by qualification and availability; tracking attendance and activities.

7. Quality Management (QM): Inspection plans, in-process controls, basic SPC, NOK handling, and audit documentation.

8. Process Management (PM): Controlling and monitoring process flows, routings, recipes, and process parameters during production.

9. Maintenance Management (MM): Supporting preventive maintenance, fault history, and condition data for maintenance decisions.

10. Product Tracking & Genealogy (PTG): Complete assignment of components, batches, process steps, and inspection results to lots or serial numbers.

11. Performance Analysis (PA): Evaluating OEE, lead times, scrap rates, and other KPIs for management and continuous improvement.

Relevance for Modern Cloud MES

Despite its 1990s origins, MESA-11 remains practically relevant: it provides a vendor-neutral checklist for MES requirements, helps avoid scope creep, and gives structure to RFI/RFP processes and specifications. Modern cloud MES approaches extend the model with IIoT integration, cloud analytics, and low-code configuration – but the 11 operational core functions remain the foundation.

FAQ

Does a MES have to cover all 11 functions? No. In practice, many solutions cover only a subset. What matters is that the business-critical use cases – such as OEE, traceability, or operator guidance – are properly addressed.

How does MESA-11 differ from newer MESA models? Newer models (e.g., the Smart Manufacturing Model) extend MESA-11 with supply chain and enterprise perspectives. The 11 original functions remain the operational core.

How does MESA-11 help with MES selection? It provides a vendor-neutral structure: which of the 11 areas does the system cover as standard? Where are add-ons like CAQ, WMS, or EAM needed? How well does the system align with ISA-95 across these functional blocks?