This free interactive 3D model maps a complete industrial SCADA system onto the Purdue Enterprise Reference Architecture (ISA-95) — the standard way of layering operational technology. It shows how signals travel from field sensors and actuators up through PLCs/RTUs, the control network, SCADA/HMI servers and a historian, across an OT/IT DMZ, and into the MES and enterprise business systems. Click any component to see its role, the level it sits on, and how it connects to the layers above and below.
The explorer covers every Purdue level of a typical SCADA deployment:
• Level 0 — Field devices: sensors, transmitters, valves, motors and other actuators that touch the physical process. • Level 1 — Basic control: PLCs and RTUs that read inputs, run logic, and drive outputs. • Level 2 — Supervisory control: SCADA servers, HMIs and the control network that operators watch and act on. • Level 3 — Site operations: the historian (long-term process data), batch/MES systems and engineering workstations. • DMZ — the OT/IT demilitarized zone that brokers traffic between plant and business networks. • Levels 4–5 — Enterprise: ERP, business planning and corporate IT.
The Purdue model (formalized in ISA-95) splits an industrial system into hierarchical levels so each layer has a clear job and a defined trust boundary. At the bottom, field instruments (Level 0) feed PLCs and RTUs (Level 1) that execute real-time control. Those controllers report up to SCADA servers and HMIs (Level 2) over a dedicated control network, where operators supervise the process and historians log every tag. Site-wide operations and MES live at Level 3, and corporate IT/ERP at Levels 4–5. A DMZ between the OT side (0–3) and IT side (4–5) is the security chokepoint: it lets data flow up for reporting without exposing control equipment directly to the business network or internet.
1. Drag to orbit the architecture, scroll to zoom, and pan to move around. 2. Click any node — a sensor, PLC, RTU, SCADA server, historian or DMZ firewall — to highlight it and read its role and level. 3. Trace a signal upward: field device → PLC/RTU → control network → SCADA/HMI → historian → DMZ → enterprise, to see how the Purdue layers connect.
SCADA stands for Supervisory Control and Data Acquisition. It is the system of software and hardware that lets operators remotely monitor and control an industrial process — gathering data from field sensors and PLCs/RTUs, displaying it on HMIs, logging it to a historian, and sending control commands back down to the equipment.
A PLC (programmable logic controller) is optimized for fast, deterministic local control, typically within a plant or panel. An RTU (remote terminal unit) is built for remote, often geographically dispersed sites — it is hardened, low-power, and good at telemetry over long-distance or wireless links. The lines have blurred, but PLCs lean toward high-speed control and RTUs toward remote data acquisition.
The Purdue Enterprise Reference Architecture is a layered model (Levels 0–5) for structuring industrial control systems, adopted by the ISA-95 standard. It separates field devices, basic control, supervisory control, site operations, and enterprise IT into distinct levels with defined boundaries, which makes the system easier to design, manage and secure.
An HMI (human-machine interface) is the operator-facing screen of a SCADA or control system. It visualizes the live process — tank levels, motor states, alarms, trends — and lets operators issue commands. HMIs sit at Level 2 of the Purdue model, fed by the SCADA servers.
A historian is a specialized time-series database that records process tags (temperatures, pressures, flows, statuses) over long periods at high resolution. Engineers use it for trending, troubleshooting, reporting, and regulatory records. It typically lives at Level 3 of the Purdue model.
The DMZ (demilitarized zone) is a buffer network between the operational technology (OT) side of the plant and the corporate IT side. It hosts brokers, replicated historians and jump hosts so business systems can pull data without ever connecting directly to control equipment — a core defense for industrial cybersecurity.