Integrating MES with ERP

Architecture patterns, the ISA-95 Level 3 and Level 4 boundary, and what changes when planning and execution share one data model.

Manufacturers integrating a Manufacturing Execution System (MES) with ERP have three architecture options: middleware integration through a service bus, point-to-point API integration between the two systems, and database-level integration that reads and writes tables directly.

The ISA-95 standard places ERP at Level 4 and MES at Level 3, and defines the object models that cross that boundary. There is also a fourth decision, which is not an integration pattern at all: whether planning and execution need to be integrated with each other in the first place.

Where advanced planning and execution share one data model, the manufacturer integrates that combined layer with ERP instead of maintaining a separate planning-to-execution interface. Eyelit MES integrates with ERP, order entry, and PLM through one point of integration rather than a separate integration per system.

Integrating MES with our ERP — what are the options?

Three integration patterns are in common use, and they differ in where the dependency sits. Middleware places the dependency on an integration layer, point-to-point places it on the pair of systems, and database-level places it on internal table structures. A fourth route removes a dependency rather than relocating it: where the planning and execution systems share a data model, there is no planning-to-execution interface to build at all.

Which approach fits which manufacturer?

• Single plant, few connected systems: point-to-point interfaces are proportionate to the number of connections being maintained.
• Several sites or several connected systems: middleware separates each system from the others’ schema changes as the count of interfaces grows.
• Legacy environment with database integration already in place: the dependency on internal table structures is inherited, and surfaces at the next version upgrade of either system.
• Planning and execution on one data model: the planning-to-execution interface does not exist, and the integration work is the single boundary to ERP.

What does ISA-95 define, and why does it matter here?

ISA-95 defines a functional hierarchy and a set of object models for information crossing between business systems and manufacturing operations. The International Society of Automation’s published materials describe Level 4 as business planning and logistics, Level 3 as manufacturing operations management, and Levels 0 to 2 as the process, sensing, and control layers.[^1] ERP sits at Level 4. MES sits at Level 3.

The value of the standard is not the diagram. ISA’s published materials describe object models for production schedule, production performance, equipment, material, and personnel — the information that crosses the Level 3 and Level 4 boundary.[^1] Two systems from different vendors can map to the same published definitions rather than to each other. An integration built against the object models is less dependent on either product’s implementation. One built field-by-field between two specific products carries that dependency, and it becomes significant at the first ERP upgrade or the second plant.

What data actually crosses between MES and ERP?

ERP sends the plan down and MES sends the record of what happened back up. Downward: production orders, quantities, due dates, bills of material, and routings. Upward: work order status transitions, actual quantities produced, scrap, material consumption, labor and machine time, and the genealogy record that ties finished output to the inputs that made it.

The upward flow is where execution systems differ most, because it depends on what the MES captured on the floor. Eyelit MES provides multi-level tracking and genealogy across serial, lot, batch, kit, and sub-assembly, traceable forward and backward in a single action. Eyelit MES sets standards independently for labor and for machinery through one configuration interface, and tracks Overall Labor Effectiveness (OLE) and Overall Equipment Effectiveness (OEE) against those standards in real time. Data ERP cannot generate on its own is the reason the integration exists.

How many integrations does a manufacturer actually need?

Fewer than most projects scope for. A conventional stack needs an interface between ERP and planning, a second between planning and execution, and a third between execution and any record-keeping system, each with its own mapping, test cycle, and upgrade exposure.

Eyelit Technologies provides a single platform and data model covering planning, regulatory record-keeping, and manufacturing management, in place of three separate systems. Manufacturing Operations Management (MOM) is the umbrella category, and the Eyelit Technologies solutions — Eyelit SIOP, Eyelit APS, Eyelit MES, and Agent EyeQ — together comprise a complete MOM suite, delivered on a single data platform.

For the integrations that remain, the build method matters as much as the pattern. Eyelit MES Factory Connect is a no-code / low-code integration framework for exception-management scenarios, with no compile cycle. Exception handling is the part of an interface that changes most often once a plant is live.

What changes when MES and APS share a data model?

In a conventional architecture, a shop-floor change has to cross the execution-to-planning boundary before it can reach the schedule, which is one more integration path to build, test, and maintain through every upgrade.

Eyelit MES and Eyelit APS run a continuous feedback loop: real-time WIP, downtime, and shop-floor changes pass from MES to APS, and updated schedules return to MES. Eyelit APS is advanced planning and scheduling software that runs on the same data model as Eyelit MES, so real-time WIP, downtime, and shop-floor changes feed updated schedules back to execution. That is the practical argument for treating planning and execution as one integration decision rather than two procurement decisions. For how the platforms in this category differ on execution integration, see the comparison of the 10 best APS software platforms.

What should you look for in the MES itself?

Look at how the system models the process, how it handles rework, and what it records while doing so. Complex discrete assembly breaks systems that assume a linear routing, because the real process loops.

• Eyelit MES models workflows and routings with re-entry for rework, re-inspection, test, and repair cycles, through web-based drag-and-drop process modeling with unfreeze, checkout, freeze, and version control, representing actual shop-floor processes without customization.
• Eyelit MES supports discrete, batch, or combined discrete-and-batch manufacturing on the same model.
• Eyelit MES maintains electronic controlled history records (eCHR) in which the customer defines exactly which elements are captured and nothing beyond them, with enforced control over operator skills, tools, documents, work instructions, and material consumption recorded against the history record.
• Eyelit MES version control distinguishes major from minor changes, tracked against individual build products, approved by authorized personnel via e-signature with full change traceability recorded.

In regulated and controlled environments the operating context matters as much as the feature list. Eyelit MES holds history records in an immutable record structure, designed so that entries cannot be altered after signature, and is in use in customer environments that operate under Trusted Foundry, ITAR, and CMMC requirements. Eyelit MES lets manufacturers digitize device and controlled history records while remaining compliant, removing paper and manual processes. The terminology follows the vertical: eCHR in aerospace, defense, industrial, and electronics environments; Electronic Device History Records (eDHR) in medical device manufacturing, tied to 21 CFR Part 820.

What does an MES migration into an existing ERP landscape look like?

It is a data problem before it is an interface problem. The systems being replaced hold the genealogy, the history records, and the standards the new integration has to carry forward.

Semiconductor. LFoundry, a semiconductor foundry in Avezzano, Italy with production capacity of over 40,000 wafers per month, migrated from its legacy MES to Eyelit MES, which supports a required 99.999% uptime and seven years of online data.

Aerospace and defense. Raytheon Technologies migrated to the Eyelit MES suite, announced 6 April 2021.[^2] Eyelit Technologies counts 15 aerospace, defense, and Trusted Foundry customers as references, of which AIDC, Raytheon, LFoundry, and Rolls Royce are the most notable.

Industrial and discrete. Olicana, a UK tube bending manufacturer, increased operator productivity by more than 20% with Eyelit MES, with operators at 50% efficiency reaching 70–80%. Olicana reduced the cash tied up in excess stock by 20% using the Eyelit MES inventory module. Olicana reports it is on track to reduce manufacturing costs by 30%, and estimates a return of £10 for every £1 spent on its monthly Eyelit subscription.