ERP, MES & SCADA.
Who does what.
Three systems run a factory — and they answer three different questions on three different clocks. ISA-95 is the international standard that defines where each one ends, where the next begins, and how they exchange data. It is the foundation of every OT/IT integration programme. Here is the model, level by level.
Five levels.
Click each one.
ISA-95 organizes a manufacturing enterprise into functional levels, from the physical process at the bottom to business planning at the top. Every system in your plant belongs to exactly one of them.
ERP — the business clock.
The enterprise layer plans what to make, buy, ship and invoice. It thinks in orders, costs and inventory — not in machines. It has no idea what happened on Line 3 at 09:42, and it shouldn't.
ANSWERS
TIME HORIZON
SYSTEMS
CORE OBJECTS
MES/MOM — where Kaizen Tech lives.
The execution layer turns ERP orders into shopfloor reality: dispatching work, collecting machine and operator data, enforcing quality, tracking every lot. It is the only layer that speaks both languages — business above, machines below.
ANSWERS
TIME HORIZON
SYSTEMS
CORE OBJECTS
SCADA — the machine clock.
Supervisory control monitors and commands the process in real time: visualizing lines, raising alarms, logging process values. It knows everything about the machine and nothing about the order it is running for.
ANSWERS
TIME HORIZON
SYSTEMS
CORE OBJECTS
PLCs — the reflexes.
Controllers read sensors and drive actuators in millisecond loops. This is where control logic lives — and where modern protocols like OPC UA and MQTT expose clean, structured data upward.
ANSWERS
TIME HORIZON
SYSTEMS
CORE OBJECTS
The process itself.
Cork being ground, buses being assembled, milk being filled. Everything above this level exists for one purpose: to make this level run better — faster, safer, with less waste.
ANSWERS
TIME HORIZON
SYSTEMS
CORE OBJECTS
Three systems,
three clocks.
The cleanest way to understand the stack: each layer operates on a different time scale. Most integration failures happen when one layer is forced to answer questions on another layer's clock.
The same factory,
three perspectives.
None of these systems replaces another. An ERP that tries to run the shopfloor fails. A SCADA that tries to manage orders fails. The value is in the contract between them.
| ERPLEVEL 4 | MES / MOMLEVEL 3 | SCADALEVEL 2 | |
|---|---|---|---|
| Core question | What should we make, and what did it cost? | What is happening on the line right now — and was it done right? | Is the machine running inside its limits? |
| Time horizon | Months to days | Shifts to minutes | Seconds to milliseconds |
| Data granularity | Orders, totals, costs | Events, lots, units, reasons | Tags, signals, alarms |
| Typical users | Planning, finance, procurement | Operators, supervisors, plant managers | Control-room and automation engineers |
| Core objects | Production orders, BOMs, inventory | Work orders, genealogy, OEE, quality records | Setpoints, process values, interlocks |
| When it's missing | No plan, no costing, no procurement | The ERP-to-shopfloor gap: paper, Excel, and tribal knowledge | Blind process, manual control |
What actually flows
between the levels.
ISA-95 defines the exchange: plans flow down, reality flows up. The MES sits in the middle and translates — orders into work, signals into events, events into answers the business can use.
Common questions
about ISA-95.
What is ISA-95?
ISA-95 is the international standard (also known as IEC 62264) that defines the functional hierarchy of manufacturing automation systems — from physical processes (L0) to business planning (L4). It gives manufacturers a common vocabulary for defining where each system begins and ends, and what data flows between them.
What level does MES sit at in ISA-95?
MES/MOM sits at Level 3 — between the ERP's planning world (L4) and the SCADA and PLC control world (L1/L2). Level 3 is responsible for manufacturing operations management: dispatching work, collecting data, enforcing quality, and tracking every lot from start to finish.
What is OT/IT integration?
OT/IT integration is the discipline of connecting Operational Technology (the machines, PLCs, SCADA, and sensors on the shopfloor) with IT systems (ERP, cloud platforms, analytics). The MES/MOM at Level 3 is the primary integration layer — it speaks the languages of both worlds and translates machine signals into business-readable events.
Why do factories need an L3 MES layer?
Most factories have L4 (ERP) and L2/L1 (SCADA/PLCs), but no system connecting them. The gap is filled by paper, Excel, and re-keyed data — which is fragile, slow, and invisible to analytics. An MES at L3 closes that gap: it turns ERP orders into shopfloor work, collects real-time execution data, and returns confirmed actuals and genealogy back to the enterprise layer.
How does MES integrate with ERP systems like SAP?
The standard ISA-95 exchange between L4 (ERP) and L3 (MES) runs in both directions: production orders, BOMs, and schedules flow down from ERP to MES; order confirmations, actual consumptions, lot genealogy, and KPIs flow back up. Technically, this is delivered via middleware APIs, OData services, or direct database integration, depending on the ERP platform.
Most factories have L4 and L2. The gap in between is where value leaks.
Paper, Excel, and re-keyed data live in the missing L3. Implementing MES/MOM — and integrating it properly in both directions — is exactly what we do.