The levels are 0 (process / field devices), 1 (basic control: PLC), 2 (supervision: SCADA/HMI), 3 (site operations: MES, historian), 4 (business planning) and 5 (enterprise). A DMZ, often called “level 3.5”, sits between IT and OT so traffic terminates there instead of passing straight through. Because modern IIoT and cloud connections can bypass levels, the model is today used as a flexible roadmap.
What is Purdue Model?
The Purdue Model is the reference architecture that layers industrial control system networks from the process itself up to the enterprise network and underlies segmentation.
