industrial//industrial automation//automation pyramid
The automation pyramid is the classic ISA-95 stack of an industrial plant, from the physical world to the business, with one level per kind of decision. It runs from the physical process at level 0 to the ERP at level 4.
The automation pyramid is the classic ISA-95 stack of an industrial plant, from the physical world to the business, with one level per kind of decision. It runs from the physical process at level 0 to the ERP at level 4.
Level 0, physical processTemperature, pressure, flow, motors, pumps, valves, tanks.
Level 1, sensors and actuatorsTransmitters of temperature, pressure, flow, level, proximity and position; motors, valves, servos, contactors, drives.
Level 2, controlPLC, PAC or DCS, where the control logic executes (if the level is above 90 %, close the valve). The strictest determinism and real-time requirements live here.
Levels 2 to 3, HMI and SCADAThe operator sees the process, changes setpoints, acknowledges alarms and watches trends; SCADA also acquires and aggregates data.
Level 3, MES or MOMProduction orders, traceability, batches, quality, OEE, detailed scheduling, consumption, actual output. The bridge between OT and IT.
Level 4, ERPPurchasing, sales, inventory, logistics, finance, business planning.
The ERP decides what to make, the MES organizes how to make it, and the PLC or DCS make it physically happen.
Read as control, the pyramid is a loop hierarchy ordered by time scale, the factory version of hierarchical control. The drive closes current loops in microseconds, the PLC closes temperature, pressure and position loops in milliseconds, the operator at the SCADA screen adjusts setpoints over minutes, the MES replans in hours and the ERP in days. Each level treats the one below as an ideal actuator that does what it is told and the one above as a constant, and that separation of time scales is what lets each be designed on its own. When two levels come too close in speed, they fight. Compared with a drone, the plant has thousands of signals and lives for decades, and touching something that works needs a serious justification.
Numberings differ between sources: some count sensors and actuators as level 0 with the process and the PLC as level 1 (the Purdue model's habit), others split the process from the instruments as above. The order of the levels is the stable part, and the arrows are too: data and states climb, orders and setpoints descend. The pyramid is a map of responsibilities rather than a wiring diagram, and a modern plant rarely moves data strictly level by level.
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, the corporate level.
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).