Answer
ERP manages resources across the whole company, SCADA collects data from equipment, and an MES sits between them: it turns an ERP order into tasks for the shop floor, collects actual execution data, and sends the result back to ERP. They are three levels of one chain, and none of them replaces the others.
What ERP does
ERP manages orders, purchasing, inventory, and finance across the company. It knows what has to be produced and by when, but it does not see work in progress on the shop floor: which order is falling behind right now, which operation is idle, where defects have been recorded.
What SCADA does
SCADA is part of a plant's industrial control system (ICS). It collects data on how equipment runs: status, parameters, signals. Without integration, this data is not linked to production orders: you can see that a machine was running, but not which order it was working on or with what result.
What an MES does
An MES works at the shop-floor level. It:
- Receives an order from ERP and breaks it down into operations according to the routing
- Assigns tasks to lines, work areas, and workstations
- Collects actual execution data from operators and equipment
- Records quality inspections, batches, and serial numbers
- Sends confirmed results to ERP
That is why an MES is useful even for companies that already have ERP and SCADA, if they need to see what is happening on the shop floor right now.
How SimpleMES does it
SimpleMES works between ERP and the automation layer. It connects to ERP systems via REST API and web services. Equipment data comes in through connectors such as OPC UA and message brokers such as RabbitMQ; the method is chosen to fit the interfaces of the customer's control systems. Other systems can exchange data with SimpleMES through files.
Operators work with the tasks for their workstation on a terminal, tablet, or PC on the shop floor: they start and stop operations and enter output, defects, batches, and parameters. This way, every equipment record is tied to the order and operation it belongs to.
How SimpleMES was designed is covered in the SimpleMES case study.
