A MES (Manufacturing Execution System) is the software that manages and documents production execution on the shop floor: work orders, production recording, quality and traceability. It sits between machine control (PLC, SCADA) and business planning (ERP), and answers what is being made, on which order, with which lot and at what quality.
What a MES is and what it does
In the ISA-95 reference model the MES occupies level 3, between process control (where the PLC and SCADA live) and the ERP. It receives planned work orders, sequences them on real lines, captures machine and operator data during execution, computes indicators such as OEE, keeps lot traceability and closes orders against the ERP without manual transcription.
In an industrial SME the MES gap is usually filled by paper production reports typed into spreadsheets at the end of the shift. Replacing that copy work with automatic recording, often through ERP integration, is where the value starts.
Frequently asked questions
- What is the difference between a MES and an ERP?
- The ERP plans and values: orders, inventory, costs, finance. The MES executes and records: which order runs on which line, with which materials and which outcome. The ERP works in days or weeks; the MES works within the shift, in real time. They complement each other and integrate.
- What is the difference between a MES and a SCADA?
- SCADA supervises the physical process in real time: variables, alarms, machine commands. The MES manages production execution: orders, lots, traceability, indicators. SCADA looks at process variables; the MES looks at orders and products, usually fed by data the SCADA or PLCs expose.
- Does an SME need a full MES suite?
- Not necessarily. Many SMEs cover the MES function with the manufacturing module of their ERP (for example Odoo) connected to plant data, starting with automatic recording of production and downtime on critical lines. A dedicated suite depends on routing complexity, traceability and sector regulation.
- What plant data does a MES need?
- At minimum: machine states (run/stop with reason), piece and reject counters, and material consumption per order. They can arrive automatically from PLCs and sensors through a connectivity layer, or be recorded on shop-floor terminals when no signal exists.