industrial//industrial automation//automation pyramid
The classic ISA-95 stack of an industrial plant, from the physical world to the business, one level per kind of decision.
The classic ISA-95 stack of an industrial plant, from the physical world to the business, one level per kind of decision.
Level 0, physical process: temperature, pressure, flow, motors, pumps, valves, tanks.
Level 1, sensors and actuators: transmitters of temperature, pressure, flow, level, proximity and position; motors, valves, servos, contactors, drives.
Level 2, control: PLC, PAC or DCS, where the control logic executes ("if level is above 90 %, close the valve"). The strictest determinism and real-time requirements live here.
Levels 2 to 3, HMI and SCADA: the operator sees the process, changes setpoints, acknowledges alarms, watches trends; SCADA also acquires and aggregates data.
Level 3, MES or MOM: production orders, traceability, batches, quality, OEE, detailed scheduling, consumption, actual output. The bridge between OT and IT.
Level 4, ERP: purchasing, sales, inventory, logistics, finance, business planning.
The one-line summary: the ERP decides what to make, the MES organizes how to make it, and the PLC or DCS make it physically happen.
What each layer is for, in the plant's own words: PLC and DCS are base control; SCADA and HMI are real time, alarms and supervision; MES and MOM are orders, traceability, quality and productivity; ERP is finance, purchasing, sales, logistics and HR. That last level is the corporate one.
The whole story of industrial digitalization is getting data to climb from the bottom without turning the architecture into chaos: the modern version inserts an edge and a data layer between control and the upper levels (data).