MES vs SCADA: two layers, one connected operation.
SCADA supervises and controls processes. MES coordinates execution, traceability, and work. The useful decision is not replacing one with the other, but defining how they share context.
Clarify responsibilities
Separate process control from production execution and work management.
Avoid brittle integrations
Connect events and data without forcing one layer to do another layer’s work.
Keep traceability
Relate plant signals to batch, order, operator, and outcome.
What SCADA is
Supervisory control and data acquisition: the system that shows process state, manages alarms and sends setpoints to PLCs. It lives at ISA-95 level 2 and works in seconds.
What MES is
The manufacturing execution system coordinates orders, materials, batches, quality, traceability and OEE. It lives at ISA-95 level 3, between control and ERP, and works in shifts and orders.
Five concrete differences
ISA-95 level (2 vs 3), time horizon (seconds vs shifts), user (control room operator vs production manager), data (process variables vs orders and batches) and question answered (what is happening now vs what we produced and how efficiently).
When you need each layer
Without SCADA there is no centralized process supervision. Without MES there is no automatic OEE, batch traceability or link between what was produced and what was planned. A plant with SCADA and Excel sheets has the first layer and lacks the second.
SCADA runs the process
It supervises variables, alarms and commands of the control layer. It is essential to operate, but it does not replace order coordination, traceability or procedures.
MES coordinates execution
It organizes what to produce, with which material, under which instruction and with which result. Its value appears when that execution is fed by reliable plant events.
Context is the bridge
iGromi relates OT sources and execution applications without turning every integration into an isolated project.
How they integrate
SCADA exposes variables over OPC UA or Modbus; a gateway publishes them into a unified namespace over MQTT; MES and analytics consume that single source. Control is not touched: it is read in parallel.
Related
Connect MES, SCADA, and industrial data
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