Key takeaways
Short answer: ERP (Enterprise Resource Planning) is the system of record for orders, inventory, finance, and master scheduling — it plans what should be made. MES (Manufacturing Execution System) is the system of record for shop-floor execution — it tracks what is actually being made right now. They integrate at the production order: ERP issues it, MES executes it, MES reports actuals back. Buying one expecting it to replace the other is the most common ERP/MES mistake. See also MES vs CMMS.
ERP runs the business layer of the manufacturer. Customer orders, supplier purchase orders, raw material inventory, finished goods, accounting, master production schedule, BOM (bill of materials), routings at the planning level. SAP, Oracle, Microsoft Dynamics, NetSuite, and Infor are the usual names.
Critical thing: ERP plans in time buckets — daily, hourly at best. It does not know what is happening on the line in real time. It knows what should happen.
MES runs the shop-floor layer. It receives the production order from ERP, breaks it into operations, dispatches each operation to a workstation or line, captures every operator action and machine signal, records WIP movement, enforces quality routings, and reports back actual production in real time.
Critical thing: MES operates in seconds and minutes, not days. It is the only system that knows ground truth about what is actually being made.
The handoff point is the production order:
This loop is what makes both systems valuable. ERP alone has no visibility into actuals. MES alone has no way to plan or close the financial loop.
Most ERPs sell a production module. It tracks production orders, BOMs, routings, and can record completions. It is not an MES for three reasons:
If your plant is small and your reporting needs are loose, an ERP production module may be enough. If you need real-time visibility, genealogy, or are regulated, it is not.
OEE software is closer to MES than ERP. It captures machine signals and reports Availability, Performance, and Quality in real time. A dedicated OEE platform may not have the full MES execution stack (dispatch, routings, electronic batch records) but it owns the real-time production-monitoring layer that ERPs cannot do.
For many SMB manufacturers, the right stack is: ERP for the business layer, OEE software for real-time production visibility, CMMS for maintenance. MES enters the picture when production complexity or regulatory requirements demand it.
1. Expecting ERP to replace MES. Vendors will tell you it can. It cannot for any non-trivial plant. The data resolution is wrong.
2. Buying MES without ERP integration scope. MES that does not integrate cleanly back to ERP creates a second source of truth for inventory and production, which causes audit nightmares.
3. Treating OEE software and MES as substitutes. They overlap on real-time monitoring but MES does dispatch and execution that OEE platforms do not. They are complements where MES is needed.
See how Fabrico captures this automatically — explore OEE for manufacturing or book a demo.
It depends on complexity. Simple discrete production with low SKU count may run fine on ERP + OEE. High-mix, regulated, or traceability-heavy production needs MES.
No. SCADA is the layer below MES, controlling and monitoring the equipment. MES is the layer above, managing the production order and operator workflow.
Between SCADA and ERP, overlapping with MES on real-time monitoring. For plants without MES, the OEE platform may be the closest thing they have to real-time production visibility.
Suite versions can be convenient but typically lag best-of-breed. Most successful MES deployments are best-of-breed MES integrated with the ERP via well-defined APIs.
Yes, that is part of the design. MES is meant to keep production running even when upstream systems are unavailable. It queues actuals and sends them when ERP comes back.
Login
Blog
