MES, ISA-95, MESA-11, cMES, NAMUR – Why So Many Standards?

MES is a loaded term. Ask two people in manufacturing to define it and you’ll likely get two different answers. The definition will depend on their vertical, current vendor, and which type of manufacturing operations they run.

This is because the acronym, which stands for Manufacturing Execution System, was coined after the underlying technology emerged and it quickly became a buzzword. As vendors jumped on the bandwagon, calling their disparate solutions ‘MES’, the term became diluted.

In this post, we’ll delve deep into the attempts from organizations such as the Manufacturing Enterprise Solution Association (MESA) and the International Society of Automation (ISA) at standardizing the definition to make it less trivial.

Understanding these models and standards can help you better understand manufacturing execution systems and evaluate their modern alternatives.

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The most widespread definition of MES is perhaps the MESA model, which defines MES by function areas.

MESA, was created in the 1990s to advise on the execution of MES systems and address their growing complexity.

In 1997, MESA formally defined the scope of MES through 11 core functions, called the MESA-11 model. These functions stem from the view of a plant and include:

1. Operations/Detailed Sequencing
2. Dispatching production units
3. Product tracking and genealogy
4. Labour Management
5. Quality Management
6. Maintenance Management
7. Resource allocation and status
8. Document control
9. Performance Analysis
10. Process Management
11. Data Collection and Acquisition
    

In 2004, the model’s focus increased to include business operations. In addition to core operations, the model included focuses like supply chain optimization and asset optimization. This update is the Collaborative MES, or C-MES.

According to MESA, this model focused on how core operations activities interact with business operations. The model takes into account increased competition, outsourcing, supply chain optimization, and asset optimization.

The C-MES interfaces with other business operation areas around the edges. These include supply focused systems (Procurement SCP); customer-focused systems such as CRM and service management; financial and performance-focused systems such as ERP and Business Intelligence BI software; product-focused systems such as CAD/CAM and PLM; logistics systems such as TMS and WMS; controls (PLC, DCS); and compliance systems (DOO management, ISO, EH&S).

Finally, in 2008, the model was expanded to its current version, which spans from production, to plant operations, to business operations, and even to strategic initiatives such as lean manufacturing, quality and regulatory compliance, product lifecycle management, real-time enterprise, asset performance management, and others.

At its core, MESA’s definition of an MES is a functional definition based on the different functions an MES should serve. In order for a system to be an MES, it must have all the functional groups or a reasonable combination of them. But the definition has evolved over time. With C-MES, the MES served as an intermediary between automation and corporate management, and also as a data and information hub. It is not only a collection of functions but an integration hub for information throughout the company.

ISA-95was jointly developed by the International Society of Automation (ISA), formerly known as the Instrumentation, Systems, and Automation Society, and the American National Standards Institute (ANSI). The development of the ISA-95 standard began in 1995 when computers began to penetrate manufacturing’s information and control systems.

Unlike the MESA model, which focused on business processes, the ISA-95 model focuses on information architecture. The ISA-95 model divides production systems into 5 levels, based on the Purdue Enterprise Reference Architecture (PERA) model.

In this way, the ISA-95 standard helps define boundaries between systems. Intelligent devices, such as sensors, belong to Level 1. Control systems such as PLCs, DCS, OCS, belong to Level 2. MES, belong to Level 3. ERP to level 4.

By situating MES on Level 3, ISA-95 implies that MES connects production with enterprise systems, manages workflows to produce end products, maintains records of production, and optimizes the production process.

The goal was to develop a standard that would enable efficient interfacing and integration between an ERP system and an MES. This would facilitate effective communication between stakeholders, lowering the total cost of ownership and enabling error-free integration.

As we’ve seen, MESA defines MES by function, and ISA-95 defines it by information architecture. However, since every industry and type of manufacturing operation has different requirements in their manufacturing, quality, business processes, and regulatory environment, MES vary by industry and type of manufacturing operations.

There have been industry-specific attempts at standardizing MES definitions. NAMUR, for example, is a group of end-users particularly involved in the process industry (chemical and pharma for the most part). Their recommendations are based on ISA-95, but the group makes more concrete definitions for their industry’s needs.

On a broader level, we can distinguish between Process and Discrete industry verticals. Naturally, each type of operation has a different set of requirements, so an MES serving each one will differ in important ways.

Process verticals thus view MES as the machine and plant control systems. While discrete industries view the MES as more of an online information system, feedback, and control system for production.

In addition to the standards we’ve covered so far, there are other standards such as the VDI standard. The VDI standard was developed by the Verein Deutsche Ingenieure in 2004 on the basis of the standards we covered above. As with all standards, the goal of VDI was to give MES a fixed meaning that would prevent vendors from trivializing the term for marketing purposes.

Recently, analysts have observed that MES are moving toward an applications and micro-services model. As a result, MES vendors are starting to move away from a position as all-encompassing solutions. Instead, they’re experimenting with selling modularized functionality. With the emergence of IIoT, many have even begun to question whether MES are still relevant in the digital era. Right now, the market is still evolving. But it will be interesting to watch which direction it moves in the next five years. IIoT applications? Traditional MES? Or both?

As you can see, there have been multiple attempts to standardize the MES definition. For the subject matter expert, these standards and models might be useful. However, for the regular end user of MES, they can be more confusing than illuminating. Perhaps a better way to define manufacturing execution systems is by the common features they tend to have, usually around 5 main areas: production functions, quality, human resources, data collection, and systems integration.

If you’ve ever tried to align your operations with an MES framework, you’ve probably encountered an alphabet soup of standards i.e. ISA-95, MESA-11, NAMUR, cMES. It’s fair to wonder how they all appeared and why so many exist.

The short version is that ‘manufacturing needed a shared vocabulary’.

During the 1990s, enterprise IT systems were expanding rapidly. That growth exposed a widening gap between business systems like ERP and the day-to-day activity on the shop floor. Every MES project had to start from scratch because no one agreed on what the system should actually do or how it should connect to other layers.

Industry groups stepped in to fix that.

MESA (Manufacturing Enterprise Solutions Association) released its first functional model called MESA-11, to describe MES capabilities such as scheduling, quality management, and production tracking.

ISA (International Society of Automation) followed with ISA-95, which defined how systems should link together, from machines (Level 0) to business systems (Level 4).

In parallel, groups like NAMUR focused on process industries, adding layers specific to regulated environments.

Each framework targeted a different part of the same puzzle: defining functions, clarifying system boundaries, and accounting for sector-specific needs. The result helped manufacturers move toward consistency, even if it also introduced some overlap and extra complexity.

At its foundation, MES standardization aims to make systems interoperable, define clear responsibilities, and create a common way to represent operations. But as production networks have grown more dynamic with multiple products, multiple sites - the limits of rigid, hierarchical standards have become clear.

Modern, modular approaches such as Composable MES build on those same principles of scope, integration, and governance, but adapt them to a flexible, app-based architecture better suited to current manufacturing realities.

Manufacturing moves fast. Product mixes shift, lead times shrink, compliance expectations tighten. Yet a lot of plants still run on MES architectures that were designed long before cloud computing, AI, or edge systems existed. Those frameworks did their job for years, but they weren’t built for the pace or complexity of modern production.

Composable MES (cMES) was developed to close that gap.

cMES breaks the idea of the single, all-encompassing MES into smaller, purpose-built apps. Each one handles a clear function i.e tracking, quality checks, maintenance, etc. and they connect cleanly with the rest. Instead of installing one rigid system, teams assemble a set of components that match how their operations actually work.You end up building the system around your process, not the other way around.

Extending and Replacing Legacy Standards

Frameworks like ISA-95 and MESA-11 laid important groundwork. They defined structure, data flow, and system boundaries when manufacturers first needed a shared playbook. cMES keeps that foundation but removes the fixed hierarchy that made older systems slow to change.

The difference shows up in practice. Traditional MES depends on top-down control and heavy customization. cMES distributes control across modular apps that run in the cloud. Engineers can adjust logic through configuration instead of waiting on a vendor or long IT cycle. Changes roll out in days instead of months, which matters when new product introductions or compliance updates can’t wait.

This isn’t only a new software model, it changes how production teams manage and improve their own systems.

Built for Modern Manufacturing

cMES technology mirrors how plants operate today:

• Cloud infrastructure – accessible across sites, scales with demand.

• Microservices – each function runs on its own, so updates stay contained.

• No-code environments – process engineers can build and modify apps directly.

• Open integrations – connects to machines, enterprise data, and edge devices without heavy middleware.

• AI-driven tools – support monitoring, diagnostics, and prediction inside the same environment.
  
  

This model lines up with digital twins, live data visibility, and global traceability efforts now taking hold across manufacturing. It adds flexibility where legacy systems enforced rigidity, while keeping the same expectations for accuracy and control.

It’s easy to get caught in the weeds when looking at MES standards. Underneath the technical language, most of them fit into four groups: functional, architectural, industry-specific, or modular.

The table below helps outline where each one applies and what it does best.

Each framework stems from a different mindset about how manufacturing systems should behave. MESA-11 focuses on functions. ISA-95 defines how systems connect. NAMUR refines those ideas for process industries. And cMES extends them into a modular, configurable environment that matches how modern plants evolve.

The underlying architecture is what’s shifting. cMES keeps the discipline of standard-based operations but allows faster adaptation, better visibility, and tighter alignment with digital manufacturing practices all without losing control or compliance discipline.

Each MES standard looks at manufacturing from its own angle. MESA-11 maps out what MES should actually do. ISA-95 lays down how systems talk to each other. NAMUR adds the detail needed for process industries. Different playbooks, same intent: make production data reliable, connect systems that never spoke well together, and keep operations consistent.

1. Data Integrity, Traceability, and Visibility
If the data isn’t right, nothing else matters. Every MES standard is built around that idea. You need records you can trust i.e. whether you’re tracing a batch, defending a deviation report, or figuring out why a line went down at 2 a.m.

Good MES design makes all of that visible. What used to live in paper logs or memory gets captured automatically: equipment states, operator inputs, quality results. When that information is consistent and complete, audits go faster and improvement work gets real traction.

2. Human-Centric Integration
Older systems were mostly written for machines. Operators were an afterthought i.e. press a button, clear an alarm, move on. The reality on the floor is more complicated.

Composable MES flips that focus. Tulip’s setup starts with people and workflows. Apps are shaped around how work actually happens, not how software thinks it should. That makes it easier to collect data at key points, guide steps interactively, and change things without rewriting code.

The system becomes a tool that helps people do their job, not one they have to fight.

3. Continuity Across the Digital Thread
Everyone talks about the “digital thread”, data flowing cleanly from the floor to planning systems, but getting there has always been messy. ISA-95 gave the layers names, but real-time connection has lagged behind.

Composable MES helps close that gap. Open APIs move data in both directions. Events on the line feed straight into analytics or ERP, and enterprise changes can flow back to execution. The thread finally behaves like a loop instead of a stack of disconnected files.

Beyond Standards : MES for the Next Decade
The MES world is changing fast.

For years, manufacturers worked inside rigid architectures that didn’t bend easily. The next decade looks different. Flexibility, connectivity, and embedded intelligence are now driving the conversation. Frameworks like ISA-95 and MESA-11 still matter, but they weren’t built for the volume of data, speed of iteration, or level of connectivity plants deal with today.

What’s showing up instead is a new kind of system that is modular, data-driven, and designed to evolve as operations do.

From Static Models to Composable Systems
In older MES setups, even a small process change could mean months of development and validation. A composable MES changes that dynamic. Teams can spin up or adjust apps in real time, right alongside production.

That’s not a concept, it’s already in motion. Gartner projects that most new MES rollouts within the next few years will rely on composable technology. Plants are seeing the payoff: less downtime between changes and more direct control in the hands of engineers.

Enabling Intelligence with AI and Digital Twins
AI has moved past the pilot phase. It’s turning up in operator guidance, in predictive maintenance, in quality inspection. Digital twins add another layer by mirroring live operations so engineers can test changes before they reach production.

Together, they form something that legacy MES never managed: a system that can sense, simulate, and adjust continuously. It’s less about replacing people and more about giving them better context and faster feedback.

Interoperability: The Hard Requirement
None of this progress matters if systems can’t talk to one another. OPC UA, REST APIs, and the new Open Process Automation standards are making that possible across vendors and layers.

Modern MES platforms have to plug into everything like machines, ERPs, quality systems, historians, analytics tools. Real performance gains come when data moves freely and keeps its context from the edge to the enterprise. That’s how manufacturers build visibility and resilience that last longer than the next product cycle.

MES standards still set the baseline by defining how systems function, connect, and fit specific industries. But they were created for a slower, more predictable manufacturing world. Composable MES gives manufacturers room to adapt. It keeps the structure and traceability of traditional systems while allowing rapid changes when products, lines, or regulations shift. Tulip carries that concept into practice. Its no-code, modular platform connects people, machines, and data so teams can adjust processes directly, without breaking compliance or waiting on long development cycles.

If you're interested in seeing how Tulip's MES can help improve the way you're running your operations, reach out to a member of our team today!