SCADA — Supervisory Control and Data Acquisition
Supervision and data acquisition over wide infrastructure — power grids, pipelines, water utilities, smart grid, multi-site telemetry. Client/server or web architecture, long-distance communications (DNP3, IEC 60870, IEC 61850), historian, alarm management, IIoT and MQTT Sparkplug integration.
Core principles
Designed in the 1960s to remotely operate pipelines and electrical substations. Today omnipresent wherever you need to supervise scattered assets — water, energy, gas, rail, smart cities.
Multi-site supervision
Centralizes visualization and control of hundreds or thousands of remote assets (RTUs, PLCs, IoT sensors) from a single control room.
Polling-based acquisition
Cyclical query of remote stations (1 s to several minutes). Request/response pattern on telecom protocols — different from local real-time DCS.
Historian and long-term trends
Dedicated time-series database (PI System, AVEVA Historian, InfluxDB) — millions of points archived at high frequency, then compressed for 10-20 yr analytics.
Redundant architecture
Dual SCADA servers with automatic failover. Stateless HMI clients can reconnect to the surviving server. Separate control / supervision networks.
DCS vs SCADA
Frequent confusion. Here are the structural differences guiding the choice.
| Dimension | DCS | SCADA |
|---|---|---|
| Geographic span | One site (< 1 km radius) | Regional to nationwide (up to 1000s km) |
| Control loop | Fast local loop (ms) | No local loop — done at the remote RTU/PLC |
| I/O density | 10 000 – 500 000 / site | 100 – 10,000 per substation × N sites |
| Protocol | Proprietary / PROFINET / Modbus | DNP3, IEC 60870-5-101/104, IEC 61850, Modbus TCP |
| Typical target | Refinery, power plant, paper mill | Power grid, gas, water, rail |
Major vendors
| Brand | Platform | Strength / target | Region |
|---|---|---|---|
| Inductive Automation | Ignition | Modern web-native, unlimited licensing, MQTT Sparkplug. Strong growth. | Globale |
| AVEVA (Schneider) | AVEVA System Platform (ex-Wonderware) | Oil & gas, water. Mix on-prem and cloud (AVEVA Connect). | Globale |
| Siemens | WinCC OA / WinCC Unified | Energy, infrastructure, transport. WinCC OA for very large distributed SCADA. | EU |
| Rockwell | FactoryTalk View SE | US manufacturing, integrated with PlantPAx | Amériques |
| GE Digital | iFIX / CIMPLICITY | Water, energy, manufacturing. Historical installed base. | Globale |
| ICONICS | GENESIS64 / GENESIS Hyper Historian | Building, smart cities, energy. Cloud-first. | Globale |
| Open source | OpenSCADA / Rapid SCADA / FUXA | Community solutions for small installations. | Globale |
SCADA telco protocols
| Protocol | Layer | Use |
|---|---|---|
| DNP3 | App / TCP or serial | North America — electricity, water. Time-stamping at RTU, event class handling. |
| IEC 60870-5-101 | Serial | Europe (legacy) — electrical substations, serial. |
| IEC 60870-5-104 | TCP/IP | Ethernet evolution of -101 — European/Asian power grids. |
| IEC 61850 | Ethernet (MMS, GOOSE, SV) | Modern electrical substations — multi-vendor interoperability, real-time GOOSE. |
| Modbus TCP | TCP/IP | Universal, simple, open — secondary sites and basic sensors. |
| MQTT Sparkplug B | TCP/IP (broker) | New IIoT reference — pub/sub, state machine, rich metadata. Plug & play. |
2026 trends
Web-native SCADA
Ignition popularized native HTML5/JS browser access — end of the heavy Windows client era. Major vendors follow (WinCC Unified, AVEVA System Platform).
MQTT Sparkplug B
Becoming the de-facto standard to integrate tens of thousands of remote sites via lightweight pub/sub over cellular/satellite — auto-discovery, session state, far more efficient than DNP3 polling.
Cloud / hybrid SCADA
AWS, Azure IoT, Google Cloud IoT — real-time ingestion + ML analytics. Coexists with local SCADA for operational criticality. Control stays local, analytics moves up.
Convergence with OT cybersecurity
Exposed SCADA (water utilities, energy) become NIS2 attack target #1. Purdue segmentation, operator MFA, mandatory jump server — see OT cyber hub.
Standards
- DNP3 / IEEE 1815 — Distributed Network Protocol — US reference
- IEC 60870-5 — Telecontrol — European reference for power
- IEC 61850 — Substation communication — multi-vendor
- IEC 62443 — Industrial control systems cybersecurity
- ISA-101 — HMI design — applies to SCADA screens
- ISA-18.2 — Alarm management — rationalization, flood prevention