OPC UA communication module

The Evolving Landscape of Industrial Communication

Industrial automation is undergoing a transformation. With the rise of Industry 4.0, manufacturers, utilities, and infrastructure operators are under pressure to modernize their data communication strategies. But while new devices support cloud connectivity and advanced analytics, millions of legacy assets still rely on outdated or proprietary protocols.

Enter OPC UA Communication Modules: specialized hardware or embedded components designed to bring secure, standardized, and interoperable communication capabilities to existing and new industrial devices. By enabling equipment to communicate using OPC UA (Unified Architecture)—the world’s leading industrial communication standard—these modules bridge the gap between operational technology (OT) and information technology (IT).

Whether they’re used in PLCs, sensors, robots, or edge gateways, OPC UA communication modules deliver features like robust security, hierarchical data models, and IT-friendly protocols—unlocking data silos and future-proofing equipment for digital transformation.

This article dives deep into what OPC UA communication modules are, why they matter, how they work, where they’re used, and how to select and deploy them effectively.

What is an OPC UA Communication Module?

An OPC UA Communication Module is a device or embedded hardware component that implements the OPC UA protocol stack, enabling equipment to expose data using OPC UA’s secure, standardized, and semantically rich interface.

Modules come in various forms:
• Plug-in modules for PLCs, like Siemens S7 or Rockwell ControlLogix, that add OPC UA capability.
• DIN-rail gateways that translate legacy protocols (Modbus, EtherNet/IP, PROFIBUS) to OPC UA.
• Embedded boards integrated into sensors, drives, or instruments.
• Software-based modules running on industrial PCs but sold as “virtual modules.”

Core functions include:
Hosting an OPC UA Server endpoint
Supporting OPC UA security policies (encryption, authentication)
Modeling device data in a hierarchical OPC UA address space
Enabling data subscriptions and event notifications
Managing sessions for multiple OPC UA clients

These modules standardize how industrial equipment communicates, enabling integration with MES, SCADA, historians, and cloud platforms—all while maintaining high levels of cybersecurity.

Why OPC UA Communication Modules are Critical

Achieving Interoperability

Industrial plants often use equipment from different vendors. OPC UA modules offer a vendor-neutral data model, allowing devices to integrate seamlessly.

Enhancing Cybersecurity

Legacy protocols lack encryption and authentication. OPC UA modules add TLS security, role-based access, and certificate-based authentication to protect data.

Enabling Cloud & IIoT Integration

Cloud services (AWS, Azure, Google Cloud) rely on modern protocols like OPC UA to pull data securely. Communication modules make even 20-year-old machines cloud-ready.

Supporting Rich Data Models

OPC UA’s information modeling lets devices expose structured data (Objects, Variables, Methods, Events) rather than simple flat tag lists—crucial for digital twins.

Simplifying Engineering & Maintenance

A standardized interface reduces custom coding, lowers integration costs, and simplifies future upgrades.

Types of OPC UA Communication Modules

PLC Plug-in Modules

Manufacturers like Siemens, Beckhoff, and Rockwell offer OPC UA-enabled CPU or communication cards. Examples:
• Siemens S7-1500 CPUs with integrated OPC UA server
• Beckhoff CX controllers with TwinCAT OPC UA runtime
• Rockwell’s 1756-EN4TR communication modules supporting OPC UA

Use case: Expose PLC tags directly as OPC UA nodes for SCADA or MES integration.

Protocol Gateways

DIN-rail or panel-mounted devices converting protocols (e.g., Modbus, EtherNet/IP, PROFIBUS) to OPC UA.

Vendors: Softing uaGate, HMS Anybus, Advantech WISE gateways.

Use case: Modernize legacy devices without modifying PLC logic.

Embedded OPC UA Modules

Compact boards or SoM (System-on-Module) devices that manufacturers integrate into sensors, analyzers, or VFDs.

Use case: Enable “OPC UA out of the box” for new smart sensors.

Software-Based Modules

Some vendors offer OPC UA runtime packages certified as “modules” to embed in Linux- or Windows-based devices.

Use case: Add OPC UA functionality to edge computers or industrial PCs.

Core Features of OPC UA Communication Modules

Feature
Why It Matters
OPC UA Server Endpoint
Acts as the primary communication interface for OPC UA clients.
Information Modeling
Allows structured representation of data beyond flat registers.
Secure Communication
TLS encryption, user roles, and certificates protect data.
Data Subscriptions
Push data updates efficiently rather than constant polling.
Event Support
Generate OPC UA Alarms & Events for device states or thresholds.
Method Invocation
Support OPC UA Methods to trigger device functions remotely.
Multiple Client Sessions
Allow multiple clients (SCADA, MES, analytics) to connect simultaneously.
Diagnostics Interface
Monitor communication health, errors, and performance.
Redundancy
Some modules support primary/secondary setups for high availability.

How OPC UA Communication Modules Work

Data Acquisition

Modules acquire data directly from a device’s memory, registers, or fieldbus protocols. For example:
• PLC module reads controller tags
• Protocol gateway polls Modbus registers

Data Modeling

Data points are structured into an OPC UA address space using OPC UA Objects, Variables, and Events. Metadata such as units, engineering limits, and quality status are added.

Security Management

Modules handle certificate exchange with OPC UA clients, maintain trust lists, and enforce user access levels.

Communication

Modules host an OPC UA server endpoint that clients connect to over opc.tcp:// or HTTPS. Clients can:
• Browse data hierarchies
• Read/write values
• Subscribe to data changes
• Receive event notifications

Event Handling

Modules can raise OPC UA Events for:
• Alarms (e.g., temperature > threshold)
• State changes (e.g., device offline)
• Diagnostic alerts (e.g., communication loss)

Use Cases for OPC UA Communication Modules

SCADA Integration

One of the most common uses is connecting PLCs or RTUs directly to modern SCADA systems via OPC UA. Instead of installing separate protocol drivers, SCADA clients can securely connect to the OPC UA module inside or beside the PLC.

Cloud Connectivity

Modules can feed real-time data to cloud platforms like AWS IoT, Microsoft Azure IoT Hub, or Google Cloud using OPC UA over MQTT bridges or via secure OPC UA clients deployed in the cloud.

Machine Builders & OEMs

OEMs embed OPC UA modules in new machines to offer customers a plug-and-play interface for integration with existing systems, enabling features like predictive maintenance, remote monitoring, and digital twins.

Brownfield Modernization

OPC UA communication modules allow old devices speaking Modbus, PROFIBUS, or other legacy protocols to participate in Industry 4.0 architectures—without replacing the original equipment.

Energy Management

Energy meters or power quality analyzers equipped with OPC UA modules expose measurements like voltage, current, harmonics, and consumption, enabling advanced energy analytics platforms to access standardized data.

Condition Monitoring

Modules embedded in vibration sensors or thermal cameras deliver structured data directly to maintenance systems, enabling predictive maintenance strategies.

Selecting the Right OPC UA Communication Module

Compatibility
• Verify the module supports the protocol stack needed for your devices (e.g., Modbus, EtherNet/IP).
• For PLC plug-in modules, confirm compatibility with your PLC model and firmware version.

OPC UA Features
• Look for support of latest OPC UA profiles like Data Access (DA), Alarms & Events (A&E), Historical Access (HA), or Methods.
• Confirm whether the module supports multiple concurrent sessions if multiple systems will connect.

Security
• Ensure the module supports strong encryption (Basic256Sha256 or stronger).
• Look for role-based access control and certificate management features.

Performance
• Review the maximum number of tags or data points the module can expose.
• Check supported update rates—some modules only support slow polling cycles, which might not suit high-speed applications.

Environmental Ratings
• For harsh environments, choose modules with wide operating temperature ranges, shock/vibration resistance, and IP65/IP67 ratings.

Vendor Support
• Evaluate the vendor’s documentation, firmware update policy, and technical support.
• Consider OPC Foundation certification as a quality indicator.

Challenges and Best Practices

Configuration Complexity

Detailed tag mapping and information modeling can be time-consuming. Use vendor-provided configuration tools or wizards to speed up deployment.

Network Security

Even with OPC UA’s security features, always place communication modules on a protected network segment or behind a firewall. Avoid exposing OPC UA endpoints directly to the Internet.

Certificate Management

Regularly rotate certificates and manage trust lists to maintain secure connections, especially in larger organizations where certificates may expire or need revocation.

Versioning

Standardize on compatible OPC UA versions between your communication modules and client applications to avoid interoperability issues.

Maintenance

Schedule periodic backups of module configurations, mappings, and certificates. Maintain a changelog for future audits or troubleshooting.

Vendor Solutions Overview

Vendor / Solution
Type
Highlights
Siemens S7-1500 CPU
PLC-integrated
Built-in OPC UA server, no extra module needed
Softing uaGate MB
Gateway module
Modbus RTU/TCP to OPC UA; DIN-rail
HMS Anybus OPC UA
Gateway module
Multi-protocol to OPC UA; flexible mappings
Beckhoff TwinCAT OPC UA
Software module
Supports embedded OPC UA server in controllers
Advantech WISE-710
Edge module
Modbus, REST, MQTT, and OPC UA integration
Moxa UC series
Edge computers
Pre-installed OPC UA runtime in rugged hardware

These options cover scenarios from PLC upgrades to brownfield integration to edge computing—all leveraging OPC UA.

Future Trends for OPC UA Communication Modules

Companion Specifications

More modules will support OPC UA Companion Specifications for specific industries (e.g., robots, pumps, compressors) to standardize data models and semantics.

Pub/Sub

Emerging OPC UA Pub/Sub support will enable event-driven communication with lower latency and bandwidth usage compared to traditional client-server polling.

TSN Integration

Time-Sensitive Networking (TSN) will allow OPC UA modules to participate in deterministic networks, opening new applications for real-time control.

Edge AI

Future modules will include AI/ML capabilities for local data processing, anomaly detection, and predictive maintenance—pushing intelligence closer to the machine.

Plug-and-Play

Standardization efforts will simplify auto-discovery of OPC UA devices and communication modules, reducing engineering hours during commissioning.

Conclusion

OPC UA communication modules are critical enablers of Industry 4.0, transforming legacy equipment and new devices alike into secure, interoperable data sources. Whether deployed inside a PLC, on a DIN rail, or embedded in a smart sensor, these modules expose rich, structured OPC UA data that feeds MES, SCADA, ERP, cloud analytics, and digital twins.

By understanding how these modules work, selecting the right solutions, and following best practices in configuration and maintenance, organizations can accelerate their digital transformation, improve operational efficiency, and future-proof their infrastructure.

As OPC UA continues to evolve with Pub/Sub, TSN, and standardized information models, communication modules will remain key to bridging the gap between today’s assets and tomorrow’s smart factories.

ANC-300e: Ethernet/IP & Modbus TCP to Serial Modbus RTU, DF1 Converter
The ANC-300e has the combined performance as an Ethernet and RS-485 serial converter. The gateway behaves like a protocol converter/translator that allows difficult data interchanges and connections between incompatible networks. Protocols include:

RS485 serial Protocols:
Modbus RTU, Modbus Sniffer, A.O. Smith AIN, A.O. Smith PDNP, BACnet MS/TP Client, BACnet MS/TP Server, TCS Basys Master, MSA Chillgard Monitor, DMX 512-Master, DMX-512 Slave, M-Bus Master, Metasys N2 Master, Metasys N2 Slave, Siemens FLN Master, Siemens FLN Slave, Sullair Master, Toshiba ASD Master, Toshiba PLC Master, DF1.

Ethernet Protocols:
Ethernet/IP Client/Server, AB CSP Ethernet Client/Server, Modbus TCP/IP, Profinet IO, BACnet/IP BBMD, BACnet/IP Client, BACnet/IP Server, Baumer VeriSens Client, CC-Link IE SLMP Client, MELSEC Client/Server, Generic Socket Client/Server & GreenFumeHood Client, Modbus TCP.

ANC-300e is an easily configurable Ethernet / RS-485 converter gateway, that provides integrated communication between all the above common industrial and commercial communication networks. As part of the ANC Gateway Converter Series, the ANC-300e provides a common platform which is convenient and easy to setup in all products.

The Automation Network ANC-300e Ethernet & Fieldbus Gateway Converter allows data to be seamlessly transferred between Ethernet to Ethernet and Ethernet to RS-485 networks with simple configuration.

Coming Soon: Need to get data from your EtherNet/IP or Modbus TCP/IP-based devices to your OPC UA clients? This ANC-300e additional functionality is coming shortly.