SCADA (Supervisory Control and Data Acquisition) explained simply
Imagine you have a large, complex plant site or a utility system whose technical processes you want to monitor and control centrally – whether at the control panel in the office or even on the move. That is exactly what a SCADA system enables: it collects real-time data from sensors, controllers (PLCs, RTUs) and automatically derives control commands from them – or informs you if something is not running as planned. In short: SCADA is the central nervous system for smooth operation in industry, energy, water, transport and many other sectors.
Background information
A SCADA system (Supervisory Control and Data Acquisition) combines hardware and software components in order to monitor, control and record industrial processes centrally – locally or remotely. Sensor signals, control values and status information are collected via Remote Terminal Units (RTUs) or programmable logic controllers (PLCs). With the help of communication networks – increasingly based on Ethernet/IP or TCP/IP – this data is transferred to control centres, where it is visualised and analysed. Via HMIs (Human-Machine Interfaces), operators can monitor processes, set thresholds and intervene immediately if necessary.
SCADA thus fulfils a key role in the automation pyramid. At field level, sensors and actuators operate, above them PLCs/RTUs control individual machines. SCADA consolidates this information, provides higher-level process control, data archiving, alarm management and visualisation. At the next level are systems such as MESManufacturing Execution System - software for real-time control and monitoring of entire production., which take on production planning and quality management, and finally ERPEnterprise Resource Planning - software for integrated management of all business processes and resources. systems for long-term corporate management. SCADA therefore forms the “link” between technical process control and operational production control.
Technical architecture and components of a SCADA system
A SCADA system is typically divided into several layers and modules which together enable seamless process monitoring:
- Field level: Here sensors and actuators work, recording physical variables such as temperature, pressure or fill levels and executing control signals.
- Control level: This level is dominated by PLCs (Programmable Logic Controllers) and RTUs (Remote Terminal Units). They collect the sensor data, execute initial control logic and establish communication with the supervisory level.
- Communication level: SCADA systems use standardised or proprietary protocols (e.g. Modbus, DNP3, OPC UAOPC Unified Architecture - platform-independent communication standard for secure and cross-manufacturer data exchange between industrial systems.) to transmit data securely and reliably.
- Supervisory level (Control centre): Here resides the software with HMIs (Human-Machine Interfaces), historian databases and alarm management. Operators receive visual representations (e.g. process graphics, trends), can set thresholds and intervene in real time.
The strength of this architecture lies in the clear separation of data acquisition, transmission, storage and visualisation. In this way, SCADA systems can be scaled very flexibly – from individual production lines to large, geographically distributed networks such as power or water supply systems.
SCADA in the IIoTIIoT is the internet-based networking of industrial machines, systems, and devices for data collection and process optimization. world: integration, cloud and cybersecurity
With the rise of the Industrial Internet of Things (IIoT), SCADA has gained a new role. While classical SCADA systems often operated in closed networks, modern architectures are increasingly being integrated into cloud environments and edge systems. As a result, process data can be evaluated not only locally, but also across sites and used in AI-supported applications such as predictive maintenancePredictive maintenance using data analysis and AI to forecast machine failures before they occur..
However, this development brings challenges. Cybersecurity is one of the central issues, as SCADA systems are increasingly connected via standard networks such as Ethernet or even the Internet. Open protocols such as OPC UA do facilitate interoperability, but also increase the attack surface. Modern SCADA solutions therefore rely on encrypted communication, role-based access rights and continuous monitoring of suspicious activities.
In the IIoT world, SCADA is therefore no longer just a tool for process visualisation, but a data hub: it supplies data to MES and ERP systems, feeds analytics platforms in the cloud and serves as a real-time source for digital twins. SCADA thus becomes an essential component of the smart factoryIntelligent factory with fully networked machines and systems that self-organize and produce autonomously. – but only on the condition that integration and IT security are consistently implemented.
Further information and links
- COPA-DATA: What is SCADA? – explanation of the zenon software platform and examples of SCADA use
https://www.copadata.com/de/produkte/zenon-software-plattform/was-ist-scada/ - PTC: What is SCADA? – focus on the role of SCADA in the Industrial IoT
https://www.ptc.com/en/technologies/iiot/industrial-automation/scada - SCADA Info: History of SCADA – historical development and modern trends
https://www.scadainfo.com/history-of-scada/