Manufacturing operations depend on sensors, actuators and PLCs to operate equipment, hit production targets and minimize waste. Typically, these devices come from many different manufacturers and use multiple methods of exchanging data and instructions. OPC UA provides a common language that enables this communication in a fast and reliable manner.
OPC UA—an acronym for Open Platform Communications Unified Architecture—was released by the OPC Foundation in 2008 to modernize industrial connectivity. Building on the foundation of OPC Classic, it delivers greater flexibility, enhanced security and advanced capabilities to support today’s smart manufacturing environments.
OPC UA uses internet communication technologies to enable information exchange between clients and servers. In a straightforward factory implementation, sensors and actuators are the servers and the PLCs are the clients.
Unlike its predecessor, OPC Classic, the information is shared with context (making it semantic data), rather than as values that require interpretation. This has simplified implementation and usage and supports activities like predictive maintenance.
Today, OPC UA is quickly becoming the preferred method for data exchange throughout manufacturing, linking PLCs to SCADA systems and even ERP and MES systems. It has become a core tool for achieving digital transformation and is part of Industry 4.0. It is also being adopted in other industries like building management, energy and agriculture.
How OPC UA works: Unified data communication
Unlike OPC Classic, which was limited to Windows COM/DCOM, OPC UA leverages modern internet technologies to remain platform-independent—connecting devices regardless of vendor, operating systems or programming languages. This flexibility is key for manufacturers seeking scalable, future-ready solutions.
Implementing OPC UA requires the sensor and actuator manufacturers to provide OPC server capability on their devices. In parallel, PLC makers provide the OPC client capabilities that enable information requests and command instructions. For legacy hardware and systems still using OPC Classic, add-on tools are available to extend communication capabilities. It is important to note that the use of transmission control protocol (TCP) means UPC UA is not a real-time technology. Rather, its function is for data exchange and not immediate, high-priority control.
OPC UA organizes data through a structured semantic model—adding timestamps and contextual details that clarify what the data represents, including units and descriptions. To make this process easier, industry groups have developed companion standards that define common data structures. These standards simplify integration and strengthen Industry 4.0 connectivity across diverse equipment and systems.
OPC UA vs. OPC classic
Following its release in 1996, OPC Classic gained widespread support for the ease with which it simplified connectivity between hardware from different vendors. Over time though, a number of limitations became apparent:
- Reliance on COM/DCOM technology restricted use to Windows-based devices
- Only effective for exchanging process data (lack of understanding of the values limited applications)
- Poor security, as it ran into conflicts with firewalls
- Limited scalability due to absence of semantic data and difficulty with firewalls
Rather than attempting to make tweaks and adjustments, the OPC Foundation chose to create OPC Unified Architecture. This retained the functionality of OPC Classic, but in switching to TCP, used a completely different method of data exchange.
In comparison to the original version, OPC UA is:
- OS/platform-agnostic, working with Linux, Apple and other operating systems
- Easier to connect between devices
- Based around use of rich, contextual data models
- Incorporates built-in encryption and authentication for higher security
- Able to save histories rather than simply transmitting data
- Designed for enterprise and cloud connectivity
In short, OPC UA is a shift from data access to data understanding, along with enhanced insights and reliability.
OPC UA was released in 2008 and was updated in 2018 with Publish/Subscribe (Pub/Sub) messaging. This increased speed but was still not true real-time communication. However, by using Time-Sensitive Networking (TSN) OPC UA can become a deterministic, real-time industrial communication system.
Core benefits of OPC UA for manufacturing operations
OPC UA delivers true interoperability—linking all data systems and technology used throughout a manufacturing facility. From sensors and actuators on the plant floor to PLCs, SCADA systems, Computerized Maintenance Management Systems (CMMS), and all the way through MES and ERP integration, it creates a unified data ecosystem. This seamless connectivity enables fast data sharing and precise command execution when it matters most.
In addition, OPC UA enables faster integration of new equipment into existing automation systems and lowers related costs. Plus, the baked-in security eliminates concerns over the potential for and risk of unauthorized access.
In terms of tangible benefits for manufacturing, increased data access and availability provides multiple improvement opportunities. These range from implementation of automated OEE reporting systems to improved quality reporting, faster problem detection and deeper insights into causes of loss and waste.
In addition, data from OPC UA systems can drive new Industry 4.0 maintenance strategies that improve equipment uptime, so increasing effective capacity and lowering costs. OPC UA data can also be fed into digital twins of the production system to enable better forecasting and evaluation of alternative production and maintenance schedules.
OPC UA and maintenance reliability
Most manufacturers operate some form of planned maintenance strategy. The idea is that breakdowns are avoided by conducting inspections and repairs to a schedule. However, there’s always the risk of performing the wrong maintenance, or doing it more often than is needed, which is where predictive maintenance comes in.
Predictive maintenance relies on continuous machine health monitoring, using condition-based insights to determine when work is needed to prevent failures. These systems rely on predictive maintenance sensors to track key indicators like vibration, temperature, electrical current, flow and pressure. By analyzing this real-time data, manufacturers can anticipate issues before they disrupt production and keep assets performing at their best.
Without OPC, connecting these sensors to a monitoring system, or to the CMMS, would be extremely difficult. With OPC UA, sensors can transmit data continuously or as called-upon. This feeds into the predictive maintenance system, enabling work orders to be raised and scheduled for times that minimize disruption to manufacturing. This in turn reduces unplanned stoppages and improves OEE. It can also facilitate use of asset performance dashboards that support work prioritization efforts and problem prevention.
As an example of how these predictive maintenance tools can work, consider a pump. When equipped with an OPC UA server, it can send vibration and temperature data that highlights anomalies and automatically triggers maintenance workflows.
Interoperability and the companion specification ecosystem
The goal of OPC UA is to provide a common language for communication between sensors and actuators and the machine control system and SCADA systems. However, this is complicated by the sheer variety of equipment used in manufacturing and the number of producers of each type of machine.
To avoid the problem of manufacturers of the same type of equipment—for example, a lathe or robot, each exposing different data to the OPC client—companion specifications were introduced. These provide a common data set for that particular type of equipment. This creates standardization and enables interoperability.
Today, companion specifications are available for many different types of equipment. Details are maintained on the OPC Foundation website.
As OPC UA has grown to integrate with SCADA, the same data language issues have arisen, especially with connection to MES and ERP systems. This is handled through models in the ISA-95 framework, which again provides a common language for data exchange.
Cybersecurity advantages of OPC UA
Security was not a major concern when OPC Classic provided only relatively straightforward connections between sensors and actuators and PLCs. However, as engineers wanted to create more connections and larger networks, security issues arose.
These stemmed from the COM/DCOM tools on which OPC was then based only being designed for use on a single PC. As connections spread, computers quickly ran into firewall problems when exchanging data. These were addressed, but only in ways that created opportunities for “bad actors” to access that data.
OPC UA resolved these problems through its use of technologies like TCP/IP, http and SOAP (Simple Office Access Protocol). These use certificate-based authentication to prevent unauthorized access, so providing edge-to-cloud secure communication.
Other security aspects of OPC UA are message signing and encryption that protect information integrity, and role-based access control that supports Zero Trust architecture.
Collectively, these features protect against ransomware and OT network infiltration.
Deployment considerations and challenges
OPC UA was designed for ease of integration with other applications. However, challenges remain when implementing it throughout a manufacturing plant.
The first of these is addressing the challenges posed by legacy equipment. Anything from before 2008 will at best only have OPC Classic capabilities or may have nothing at all. This is tackled by installing gateways or converters. These take the native data and transform it into OPC UA format.
A second problem often encountered is handling the increase in network traffic. This can quickly overwhelm the installed capacity within a plant, so expansion must be considered part of the implementation plan.
Most businesses find this dramatic increase in operational technology (OT) causes challenges for the IT team and often creates internal tensions. Accordingly, business leaders must work to establish responsibilities, boundaries and interfaces to ensure there is no overlap, competition or gaps in coverage.
Finally, when implementing OPC UA, the on-site controls engineers must have enough understanding of the technology to provide the support necessary. In parallel, the Maintenance team may also need training in how to take advantage of OPC UA capabilities. This will often mean providing specialist training for both groups.
OPC UA in Industry 4.0 & IIoT strategy
Digital transformation is seen as essential for every manufacturing business that wants to strengthen its competitive position. This entails adopting Industry 4.0 and Industrial Internet of Things (IIoT) technologies.
Industry 4.0 strategies depend on seamless communication between sensors, actuators, machines, and enterprise systems like CMMS, SCADA and MES/ERP. OPC UA provides the backbone for this connectivity—standardizing data exchange across every layer of your operation. While custom coding could achieve similar results, the complexity and cost make OPC UA the practical, scalable choice for manufacturers.
Once a business is using OPC UA, it has the foundations to support moves towards cloud and edge computing, and smarter automation and more autonomous operations. Digital twins and AI-powered analytics can be adopted, visibility is improved across the enterprise, and the whole system is readily scalable to handle future growth.
In conclusion, OPC UA is essential for Industry 4.0 and IIoT technologies. Businesses that don’t adopt it risk being left behind by those that do.
