Open Process Automation
Glossary

Hardware infrastructure layer — compute servers, network switches, I/O modules — built on COTS technology rather than proprietary industrial hardware.

Choosing optimal components from multiple vendors for each function. Enabled by OPA's open, standardized interfaces.

Transitioning an existing legacy DCS to OPA while maintaining continuous operations — the most common deployment scenario.

Identity verification using X.509 certificates for OPC UA connections between OPA components.

IEC 61131-3 compliant programming environment widely used for OPA control application development and deployment.

Centralized repository maintaining authoritative configuration state — control logic, alarm settings, tuning parameters, and version history.

A defined set of O-PAS requirements that a component must satisfy to be considered compliant and guarantee interoperability.

Communication layer enabling standardized data exchange between all OPA components. Built on OPC UA, replacing proprietary fieldbus protocols.

Compact variant of the COPA controller for smaller process units, skid-mounted systems, and distributed field applications.

O-PAS-compliant controller with IEC 61131-3 programming via CODESYS, OPC UA connectivity, and migration bridge for legacy I/O.

Standard commercial products (servers, switches, OS) used instead of proprietary equipment. Benefits from consumer-scale economics and frequent patches.

The core processing unit in OPA replacing the proprietary DCS controller. Executes real-time control logic using IEC 61131-3 and can be sourced from any compliant vendor.

Layered security strategy applying multiple controls at each architecture boundary, per IEC 62443.

Network communication with guaranteed, bounded delivery time. Critical for closed-loop process control. Achieved via TSN and OPC UA Pub/Sub.

Digital bidirectional field instrument protocol. OPA integrates existing devices through gateway modules in the connectivity framework.

Building a new OPA system from scratch, without legacy constraints. Allows full O-PAS compliance from day one.

Legacy field device protocol overlaying digital signals on 4–20 mA wiring. OPA supports passthrough via I/O marshalling.

Running OPA and legacy DCS simultaneously with gateway integration. Common during phased transitions.

Connecting physical field wiring to I/O cards. Electronic marshalling and universal I/O simplify engineering and commissioning.

International standard defining five programming languages for industrial controllers: Structured Text, Function Block, Ladder, Instruction List, and SFC.

International standard series for industrial automation cybersecurity. Mandated as the security framework within O-PAS.

A specification defining exact interfaces, data models, and behaviors required for plug-and-play operation between components from different vendors.

Structured evaluation of existing DCS ecosystem, dependencies, and organizational readiness. Produces prioritized roadmap with ROI projections.

Advanced control strategy using dynamic process models to predict behavior and optimize multi-variable control actions.

Lightweight messaging protocol for edge-to-cloud communication and IoT integration alongside OPC UA.

International association of automation technology users in the process industries. NAMUR NOA is a complementary architecture to OPA.

The foundational standard from The Open Group defining requirements for an open, interoperable process automation system.

Four-layer reference architecture: APP (hardware), DCN (control), Connectivity Framework (communication), System Orchestration (management).

The current major release introducing refined connectivity specifications, enhanced security requirements, and improved orchestration interfaces.

The industry consortium within The Open Group that develops and maintains O-PAS standards. Members include end users, system integrators, and technology vendors.

Primary communication protocol in OPA for secure, reliable data exchange. Platform-independent with built-in security and information modeling.

Running new OPA controls alongside legacy DCS for validation before cutover. Ensures confidence in control performance.

Incremental DCS-to-OPA transition where process units are migrated one at a time, with parallel operation and validation at each stage.

Fundamental single-loop feedback control algorithm. In OPA, PID blocks execute on DCNs with standard IEC 61131-3 function blocks.

Messaging pattern in OPC UA where producers broadcast and consumers receive relevant data. Enables efficient, scalable real-time distribution.

Steady-state economic optimization that sets targets for advanced controllers. Integrates with OPA via the connectivity framework.

Execution environment within a DCN providing deterministic, hard real-time control loop execution with guaranteed timing.

Duplicate components eliminating single points of failure. OPA supports hot standby, N+1, and voting architectures via System Orchestration.

I/O modules installed in the field near instruments, reducing cable runs and signal degradation. Connected via industrial Ethernet.

Process of applying OS and firmware updates to COTS-based OPA systems. Faster cycle than proprietary equipment.

Top management layer handling configuration, deployment, monitoring, versioning, and lifecycle control of all distributed components.

Standardized testing environment for validating OPA component conformance to O-PAS specifications before field deployment.

A global technology consortium that hosts and governs the O-PAS standard. Provides organizational structure, IP management, and certification programs for OPA.

Complete lifecycle cost including procurement, engineering, maintenance, upgrades, and decommissioning. OPA reduces TCO 25–40% vs. proprietary DCS.

IEEE 802.1 Ethernet standards providing deterministic, time-bounded data delivery for control-loop communication.

Software-configurable I/O modules handling any signal type (4–20 mA, TC, RTD, discrete, HART) without hardware changes.

Dependency on a single vendor's proprietary technology, limiting procurement options and increasing lifecycle costs.

Network segmentation from IEC 62443-3-3 isolating system components into security zones with controlled data paths.