PTQ Q2 2026 Issue

control system (DCS) or programmable logic controller (PLC), without the limitations characteristic of specific sup - plier hardware or software lock-in. End users and others can design, operate, and expand functions with a wide range of interoperable software and hardware capabilities and com - ponents from multiple suppliers, using various technologies. By decoupling hardware and software and employing a service-oriented architecture, all software functions within the scope can be executed on many different hardware platforms or processors. If implemented according to an interoperability standard, not only can software applica - tions run in most hardware, but they can also access input/ output (I/O) in any form, increasing flexibility when design - ing a system. Understanding the O-PAS scope The O-PAS scope (see Figure 2 ) encompasses today’s DCSs and PLCs for continuous, batch, and hybrid process industries. It is not designed to cover the highest and lowest level networks. Consequently, business systems will con - tinue following normal IT practices. Similarly, device-level networks will remain largely intact. O-PAS avoids safety instrumented systems (SIS), as this requires separate, inde - pendent combinations of sensors, logic solvers, and final elements to conform with ISA84 and IEC 61511 standards. The first release, O-PAS Version 1.0, emerged in February 2019. It had five sections: • Part 1: Technical architecture overview : An informative overview providing perspective on the standard’s ultimate vision. It provided an explanation of the larger technical approach. • Part 2: Security : This was developed around ANSI/

O-PAS Scope

Business systems

Advanced Control MES

DCS/HMI

PLC/HMI

SIS

DCS I/O

PLC I/O

SIS I/O

Field devices / plant

DCS Distributed Control System PLC Programme Logic Controller HMI Human-Machine interface

SIS Safety Instrumented System MES Manufacturing Execution System I/O Input/Output System

develop, publish, and evolve an open architecture and spec- ification that will be supported by industry end users, sup - pliers, system integrators, and engineering firms (see Figure 1 ). O-PAS defines an open, interoperable, and secure archi - tecture for industrial process automation systems, using existing and emerging standards from both information technology (IT) and operational technology (OT) domains whenever possible to create a standard of standards. A control system built based on O-PAS is software-de - fined. It provides all the benefits of a traditional distributed Figure 2 O-PAS covers the space between field device networks and business systems, where real-time control is executed. It does not involve process safety systems

ISA 62443 (IEC 62443) to include cybersecurity from the outset. More specific nor - mative security requirements are also detailed in Parts 3, 4, and 5, along with associated conformance criteria. These requirements have been sta - ble for some time and are still in place. • Part 3: Profiles : This includes primary profiles for conformant components and how they contribute to inter - operability requirements for component connectivity and systems management. • Part 4: Open Connectivity Framework (OCF) : Spec- ifications for interfaces necessary to achieve base connectivity for client-server and publish-subscribe envi- ronments. It provides the underlying structure, so dis - parate components can inter - operate as a system using

START

External Certication evidence

Supplies initiates the O-PAS verication process

Conformance claim

Supplier contracts with Accredited Verication Lab

Accredited Verication Lab veries conformance

Verication Matrix

Supplier’s product

Product meets Conformance Requirements?

Yes

Verication report

Accredited Verication Lab submits Verication Report

END

Figure 3 Like other industrial standards, O-PAS has a verification process to ensure prod - ucts deliver the performance and interoperability required for real-world operation

PTQ Q2 2026