Understand Embedded OPC UA

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The OPC Foundation has been working to help solve communication and connectivity problems between plant and factory floor devices and host systems and applications since 1995.

Virtually every end user, OEM, and automation supplier employs OPC standards such as OPC Data Access (OPC DA), OPC Alarms and Events, (OPC A&E), and OPC Historical Data Access (OPC HDA), to establish communications and connectivity between disparate devices.

However, no longer is connecting devices at the field, control, and operations levels sufficient; today's users also need to connect plant devices, applications, and systems up to the enterprise level. Many OPC users have also expressed concerns about the security features of OPC communications, which previously were limited with the early versions of OPC classic communications. 

The OPC Foundation recognised the opportunity to enhance interoperability and provide platform interoperability by developing new specifications through participation by a new category of enterprise and embedded suppliers in OPC Foundation activities.

The new specification — OPC Unified Architecture (OPC UA) — has been demonstrated to improve secure interoperability between all plant equipment and systems and between the plant and enterprise, helping eliminate islands of information.

The questions are: Is OPC UA real? Have suppliers begun to incorporate it within their solutions? And, if so, how are users taking advantage of these solutions?

This article, based on the session, "Transforming Manufacturing with OPC UA: From Embedded to the Enterprise," at the recent ARC World Industry Forum in Orlando, Florida addresses these questions. 

The OPC UA specifications, initially released in 2006, integrates functionality from the existing OPC specifications (OPC DA, OPC A&E, OPC HDA) into a comprehensive service-oriented architecture. OPC UA adds essential new properties, including platform independence, scalability, high availability, new security mechanisms, and web services.

OPC UA has two dimensions:
1) to provide secure interoperability at the automation level by embedding the technology within plant-level devices and applications, and
2) to extend OPC communications from the device and automation levels up to enterprise applications and systems. 

Embedded OPC UA is based on an attractive lightweight architecture, with the minimal embedded OPC UA implementation using an efficient binary communication protocol. As a result, embedded OPC UA can be ported to many embedded operating systems, including proprietary real-time operating systems.

Liam Power, Technical Director at Embedded Labs, a software company based in Waterford, Ireland, presented "OPC UA on a Chip, Redefining Automation Architecture." Liam cited examples of OPC UA applications embedded on a chip being used to provide connectivity for scheduling, control, visualisation, logging, reporting, and productivity applications.

In his presentation, Christian Schulze, Business Development Manager for Beckhoff Automation, discussed how his company has incorporated embedded OPC UA into the architecture of its products. According to Christian, OPC UA has been embedded into its Automation Controller series, which includes PLC, motion control, and graphical user interface functionality.

The embedded OPC UA server is integrated with DA (data access), HDA (historical data access), and A&E (alarm & events). The embedded OPC UA client is already integrated with IEC61131-3 programming software function blocks. 

Embedded controllers acting as an OPC UA client can initiate communications to other OPC UA server-enabled field devices and, in the near future, to HMI/MES software acting as an OPC UA server.

Mitch Vaughn, Chief Technologist, HMI Center of Competence, Siemens Industry, presented how the company integrates its solutions using embedded OPC UA. According to Mitch, Siemens introduced its first OPC UA-based product in 2008. 

Today, one of its products has been certified as OPC UA-compliant, with ten more products in the immediate pipeline.

Mitch presented how Siemens uses or plans to use embedded OPC UA solutions at all automation levels. Future products will include numeric and motion control, drive management and diagnostics, industrial network management and analytical devices. 

From Mitch's perspective, the benefits of OPC UA include standard interfaces across all automation levels, operating system independency, and a higher degree of security compared to "classic" OPC.

He also believes that OPC certification for OPC UA products will help ensure better interoperability and higher customer satisfaction and that industrial extensions will improve robustness.

In his presentation, John Krajewski, Senior Product Manager HMI/Supervisory for Invensys Operations Management, discussed how embedded OPC UA will serve as a key enabler and one of the primary real-time system connectivity tools within the company's InFusion enterprise control system, including the ArchestrA System Platform, ArchestrA Workflow, Trident safety instrumented systems, and SimSci-Esscor ROMeo plant optimisation software. 

According to Krajewski, these encourage control excellence, people excellence, safety excellence, and asset excellence, respectively.

Katherine Voss, Executive Director of ODVA, presented a vision shared with the OPC Foundation for machinery integration in the manufacturing sector. ODVA, a vendor member organization founded in 1995, has approximately 275 global vendor members.

As a standards development organization and certification body, it manages and promotes EtherNet/IP, DeviceNet, and other ODVA technologies. In March 2011, ODVA announced a machinery initiative in partnership with OPC Foundation and Sercos International to foster cross-collaboration on topics of mutual interest for machinery applications.

[Craig Resnick is Vice President of Consulting, ARC Advisory Group.]