A manufacturing execution system (MES) records what actually happens on the shop floor — which work order started on which machine, how many parts came off the line, how many were scrapped, and how long and why a machine stopped — in real time and without paper. ERP manages the company's plan and money: orders, stock, purchasing, costing and accounting. In short, ERP answers "what are we going to make?" and MES answers "what really happened?"; neither replaces the other, and when they are integrated the gap between plan and reality closes.
What really happens on the shop floor
In many plants the picture is familiar. A work order is created in the ERP, printed and handed to production. During the shift, operators write output, scrap and stoppages on a paper form; at the end of the shift the forms pile up on the supervisor's desk, and the next day someone keys them into a spreadsheet or the ERP. Management sees yesterday's output at lunchtime today at the earliest — assuming it is correct.
Three things get lost along the way. Time: problems surface a day after they happen. Detail: "machine fault, 40 min" gets written down, but which component failed, at what time and why is gone, and five-minute micro-stoppages are rarely recorded at all. Trust: manually entered data carries a high error rate, and the ERP's product costing depends on it.
No matter how well your ERP is configured, it will not close this gap, because ERP was never designed to capture minute-by-minute events on the floor. That is exactly where an MES fits.
The cost of leaving it unsolved
The price of late, incomplete shop-floor data shows most clearly in downtime. According to Siemens' The True Cost of Downtime 2024, large plants average 25 unplanned downtime incidents a month and lose 27 hours of production a month.
The same report puts the cost of an hour of unplanned downtime at $2.3 million in a large automotive plant and $36,000 in fast-moving consumer goods (FMCG) plants. (Siemens, The True Cost of Downtime 2024)
Those are large-plant figures, and a mid-sized manufacturer's hourly loss is naturally smaller. The logic still holds: you cannot reduce stoppages whose causes you never record.
In Türkiye, the foundations are often missing too. According to the TurkStat ICT Usage Survey in Enterprises 2025, only 28.3% of enterprises with ten or more employees use ERP software — 76.5% of those with 250+ employees, but just 23.6% of those with 10–49. For many manufacturers, then, the real question is not "MES or ERP?" but "which one first?"
How MES and ERP differ
Industry usually explains the split with the ISA-95 model: sensors and PLCs at the bottom, SCADA above them, MES at the manufacturing operations level, and ERP at the top, in business planning. We explain what the SCADA layer does in what is SCADA, and how to choose a platform in commercial vs custom SCADA. In practice the difference looks like this:
| Aspect | ERP | MES |
|---|---|---|
| Core question | What will we make, when, at what cost? | What is happening on the floor now, and what happened? |
| Time scale | Days, weeks, months | Seconds, minutes, shifts |
| Data sources | Sales, purchasing, accounting, stock movements | Machine signals, barcode scans, operator terminals |
| Typical output | Orders, work orders, costs, invoices | Actual quantities, scrap, downtime reasons, OEE |
| Users | Planning, purchasing, finance, management | Operators, shift supervisors, production and maintenance managers |
| Traceability | Stock movements by batch | Which batch, on which machine, in which shift, handled by whom |
The takeaway: an ERP "production module" is usually good enough to open and close work orders and backflush materials, but it does not capture floor events at minute-level resolution. An MES, on the other hand, does not manage costing, invoicing or supplier accounts. The right relationship is a loop: ERP sends the work order to MES, and MES writes actual output, scrap and consumption back to ERP.
We cover ERP scope and selection for smaller businesses in our ERP guide for SMEs.
What an MES records
A well-built MES has these modules at its core:
- Work order management: work orders from the ERP are assigned to a machine and shift; the operator sees what to make on the terminal, starts the job and completes it.
- Downtime and scrap capture: every stoppage is logged with a reason category (breakdown, waiting for material, changeover, planned maintenance) and a timestamp; scrap quantity and cause are recorded.
- OEE: overall equipment effectiveness — availability × performance × quality — is tracked live for each machine. See how to calculate OEE for the detail.
- Material and batch tracking: the system records which raw material batch went into which work order, so a quality issue can be traced backwards. We cover the end-to-end lot and serial record in our production traceability guide.
- Shift reports: the end-of-shift report builds itself; nobody collects forms.
Data arrives three ways: directly from machines (PLC, counters, sensors), from barcode or terminal scans, and from short operator entries on a touchscreen. Designed well, an MES reduces the operator's workload — choosing a stoppage reason should take seconds. An andon system that alerts the right team at the same moment makes that entry a natural part of the MES.
The same records feed planning: once changeover times are captured per product transition, production scheduling with APS can sequence similar jobs back to back automatically.
Where to start: a five-step decision framework
- Map today's data flow. Where is a work order born, how does it reach the floor, and where does production data go back to — and how late? Mark every paper and spreadsheet step.
- Name the real pain. Is the problem stock, costing and orders (an ERP pain) or stoppages, scrap and late deliveries (an MES pain)? If it is both, ask which one distorts decisions more.
- If you have an ERP, define the integration surface. Which fields flow to MES (work order, bill of materials, product code) and which come back (actual quantity, scrap, consumption)? That list is the backbone of the project.
- Pick a pilot line. Instead of digitising the whole plant at once, start with a bottleneck line or a few critical machines and see downtime causes and OEE within the first weeks.
- Write success criteria up front. Set measurable targets such as "paperless shift reports", "every stoppage has a recorded cause" and "no manual production entry into ERP", then decide on roll-out against them.
An MES can make sense on its own for a business without ERP, as long as it is designed to connect to one later. The reverse also holds: if you are planning an ERP project, agreeing early on how shop-floor data will arrive protects you from one of the traps described in why ERP projects fail.
How we handle this at Digital Bridge
Rather than installing a packaged product, we start from how your production actually flows:
- We start on site. We offer a free site assessment for Industry 4.0 projects, looking at how work orders reach the floor, how downtime and scrap are recorded today, and which machine signals can be collected.
- We build an MES around your plant. Through our MES production management service we set up work order, downtime and scrap, OEE, batch tracking and shift reporting modules according to your line's real rules.
- We connect it to your ERP. Our MES integrates with Logo, SAP, Mikro (Logo and Mikro are widely used Turkish ERP packages) and custom ERPs. Together we define which data flows in which direction and how often, and remove double entry.
- We are candid about ERP needs. If you have no ERP, or it no longer fits, our ERP development service helps clarify scope and draw the line between MES and ERP from day one.
- Hardware comes from the same team. Because software and hardware sit in one team, machine signal capture, operator terminals and barcode infrastructure are not split across separate suppliers.
Every project begins with a needs analysis, and scope, phases and fees are set out in a written proposal. For the broader picture of connecting shop-floor data to business systems, see our MES service page and our Industry 4.0 roadmap for SMEs.
Next step
You do not need a big investment decision to begin. Next week, collect the shift forms from a single line and look for answers to three questions: how many stoppages have a recorded reason, are scrap reasons consistent, and how many hours pass before the figures reach the ERP? If the answers make you uneasy, get in touch and we will plan a site assessment together and define a concrete scope for your pilot line.