Making OPC UA Models Easier: Companion Specs and Custom NodeSets Without the Headache

SPONSORED BY: Software Toolbox

As industrial systems continue to move toward consistent and standardized solutions, organizations are increasingly embracing OPC UA (Open Platform Communications Unified Architecture) not just for communication but also for data modeling. OPC UA information models, especially those based on Companion Specifications and custom NodeSets, are increasingly becoming how modern equipment, software, and operations describe, share, and consume data.

More end users now depend on equipment, control systems, and digital tools sourced from dozens of vendors, systems integrators, and OEM partners. Proprietary structures and inconsistent tag naming do not scale well in environments where interoperability is becoming a requirement. This is why Companion Specifications and custom NodeSets that were once seen as a niche layer are now getting more use when standardizing industrial information.

A Smarter Path to Interoperability: Companion Specs and Custom Node Sets

Fragmentation becomes a problem when equipment from multiple vendors or OEMs arrives with its own data structures, naming conventions, units of measure, and integration methods. Without standardized OPC UA data models, engineers cannot rely on predictable structures or consistent formatting across machines. Each new asset introduces a unique set of tag names, event structures, and metadata, forcing SCADA, MES, analytics, and other systems to be reconfigured. This process is not only costly but also undermines agility, slows production, and complicates maintenance and expansion.

This forces engineering teams to spend a lot of time normalizing and remapping data instead of using it right away, and even small changes from one OEM to another can break downstream applications, dashboards, and analytics. In multi-vendor environments, the lack of standardization becomes a major operational and engineering burden, slowing deployment and increasing long-term maintenance costs.

What Standardized OPC UA Models Deliver

Standardized OPC UA information models define how industrial assets (e.g., machines, sensors, robots, meters, and more) should be represented in a consistent, structured way, providing context for what an object represents, how it behaves, how it relates to other components, and how its units, states, and alarms should be interpreted.

How Companion Specifications Help Standardize Industrial Data

Companion Specifications are standardized information models in OPC UA that act as blueprints, defining how specific types of equipment should represent themselves. They are developed by industry working groups that say: “Here is exactly how a machine tool should look,” “Here is how a robot should expose its data,” or “Here is how a process for this specific industry should be organized”. Different industries have different requirements and Companion Specs provide a shared language so that equipment can be understood consistently across companies and sites.

Custom NodeSets: Modeling That Fits Your Operation

Custom NodeSets are similar but more focused. They are vendor or company-defined OPC UA models that provide structured layouts for a specific namespace or server structure. While Companion Specs address industry-wide standardization, custom NodeSets allow organizations to capture their own processes, naming conventions, and operational requirements.

Leveraging OPC UA’s inheritance and type system, NodeSets create reusable patterns that unify how assets are described and consumed. The shift delivers results: instead of every vendor, integrator or OEM building their own structure, leading to inconsistent interpretations, endless mappings, and brittle scripts, a shared NodeSet defines the standard once, allowing all participating systems to exchange data in a common structure.

Why Companion Specs and Custom NodeSets are Gaining Traction

The reason why Companion Specs and custom NodeSets are emerging as a key solution is simple: they solve the “Tower of Babel” problem that we have had in automation for decades. When everyone speaks the same language, integration becomes a simple configuration task instead of custom development work.

Why this matters now

As industrial organizations scale their automation and digital initiatives, understanding the role of OPC UA, Companion Specifications and NodeSets have never been more important. Here’s why:

OPC UA adoption has reached critical mass. the question is no longer “Should we use OPC UA?” but “How do we use it effectively?” Companies realize that simply having OPC UA is not enough if each team or vendor continues to create data silos.
Industry 4.0 initiatives are exposing integration pain. Many organizations have invested heavily in IIoT platforms, cloud analytics, and AI/ML projects, but they are often overwhelmed by the effort required to normalize and integrate data. If more resources are spent on integration than on gaining actionable insights, the return on investment is lost.
Standards and Companion Specifications are now mature and proven. OPC UA has been around for decades, and standards bodies such as the OPC Foundation, VDMA, EUROMAP, and leading vendors have developed implementable Companion Specifications. These are no longer theoretical. Companies are deploying equipment with Companion Specs that work reliably in production, and more organizations are seeking guidance on leveraging them effectively.

Practical Steps and Best Practices for Adopting Companion Specifications and Custom NodeSets

When organizations begin adopting Companion Specifications or creating custom NodeSets, a few best practices can help ensure consistent, scalable, and maintainable OPC UA models.

Case Study: Eliminating Custom Integrations in a Multi-OEM Environment

A window and door manufacturer faced a familiar nightmare where their highly automated plants run equipment from dozens of OEMs, each delivering its own controller platform, networking approach, and data structure. For years, the engineering team relied on extensive custom mapping, scripting, and one-off integrations just to keep production running. This approach was costly, fragile, and difficult to scale.

To improve consistency, the manufacturer set a goal to standardize on the ISA-95 JobControl model (a manufacturing operations standard) so their MES could reliably generate and dispatch job orders to each machine. But with no shared Companion Specification in place, each OEM defined its own custom model. Delivering the right structures and semantics to every machine was slow, error-prone, and required constant rework.

Standardization became essential not just for efficiency, but for ensuring that job information could move cleanly from MES to machines, regardless of vendor or equipment generation.

To address the issue, the manufacturer deployed a shared OPC UA environment and required OEM partners to load Companion Specifications and custom NodeSets that fit the standard. By giving OEMs access to a common modeling environment, every machine could be integrated using the same standards that govern the rest of the production line and MES infrastructure.

The results were significant: vendor-specific mappings disappeared as every machine aligned to a unified OPC UA model. Onboarding new equipment became faster because OEMs knew how to structure their data. Engineering hours dropped thanks to the elimination of one-off integrations. OT/IT systems received data in a consistent format, and the entire architecture became flexible. By shifting from interpreting data to agreeing on the model, the manufacturer turned interoperability from a recurring challenge into a strategic advantage.

Start Standardizing Today

Inconsistent data becomes more costly over time. Every new device adds complexity, and for companies looking to modernize and scale, now is the time to explore Companion Specifications and custom NodeSets to create a consistent, reusable, and resilient data foundation.

As more OEMs, system integrators, and end users adopt model-driven architectures, Companion Specs and NodeSets are accelerating industrial connectivity and making modern tooling easier to build and deploy. Organizations investing in these models today are setting themselves up for flexible, maintainable, and scalable operations where data stops being a barrier and becomes a genuine competitive advantage.

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