OPC rarely operates in isolation — it sits at the intersection of plant-floor control systems and broader IT/OT integration. This section covers the surrounding systems and roles, such as SCADA, DCS, PLCs, and historians, that OPC is typically used to connect.
| Term | Definition |
|---|---|
| SCADA (Supervisory Control and Data Acquisition) | A control system architecture that gathers data from distributed sensors and field devices and presents it for centralized monitoring and control. |
| DCS (Distributed Control System) | A control architecture, typically used in process industries, that distributes control functions across networked controllers rather than relying on a single central processor. |
| PLC (Programmable Logic Controller) | An industrial computer that reads inputs from sensors and executes programmed logic to control outputs such as actuators and motors. |
| HMI (Human-Machine Interface) | The software interface, typically graphical, that lets an operator view process status and issue control commands. |
| RTU (Remote Terminal Unit) | A field device that collects data from sensors and equipment at a remote site and communicates it back to a central system, often over telemetry links. |
| MES (Manufacturing Execution System) | A software system that manages and tracks production processes on the plant floor, bridging the gap between business systems and control systems. |
| ERP (Enterprise Resource Planning) | A business software system that integrates manufacturing, finance, and other enterprise functions into a single information system. |
| Historian | A specialized database optimized to store large volumes of time-series process data, often using compression to manage storage volume. |
| IIoT (Industrial Internet of Things) | The use of internet-connected sensors, devices, and analytics in industrial settings to improve monitoring, efficiency, and decision-making. |
| IT/OT (Information Technology / Operational Technology) | Refers to the convergence of traditional business IT systems with the operational technology used to monitor and control physical industrial processes. |
| Edge Device | A device located close to physical equipment that performs data collection, processing, or communication before sending data further into the network. |
| Gateway | A device or software component that translates data between two different protocols or networks, such as bridging a legacy protocol to OPC UA. |
| Aggregator | A software component that consolidates data from multiple sources or servers into a single point of access for clients. |
| Bridge | A software or hardware component that connects two systems or networks, allowing data to pass between them. |
| DAQ / DAS (Data Acquisition / Data Acquisition System) | The hardware and software used to collect, measure, and process signals from sensors and instruments. |
| ESD (Emergency Shutdown System) | A safety system designed to automatically bring a process to a safe state in response to a hazardous condition. |
| Set-Point | The target value a control system attempts to maintain for a given process variable, such as a target temperature or flow rate. |
| LAN (Local Area Network) | A computer network confined to a relatively small area, such as a single plant or building. |
| WAN (Wide Area Network) | A computer network that spans a large geographic area, typically connecting multiple LANs across sites. |