OPC Foundation Updates Field Level Communication Specs and Launches Cloud Library

New specifications address OPC UA information models and networking services, while the OPC UA Cloud Library provides information model access for applications.


Interoperability is the challenge at the heart of Industry 4.0. With the basis for the Industrial Internet of Things (IIoT) being the networking together of previously isolated systems, standardized communication methodologies are vital to industry’s digital transformation.

With its wide adoption by technology vendors, the OPC Foundation's Unified Architecture (OPC UA) has proven to be a core element of industrial interoperability. OPC UA is a machine-to-machine communication architecture compatible with multiple operating systems, programming languages, and platforms. It helps integrators and end users ease the process of integrating disparate systems and equipment—often from various vendors—through the use of semantics to provide a common structural framework for various types of data exchange.

At the 2021 OPC General Assembly Meeting, developments pertaining to these goals were discussed, including the release of new specifications for OPC's Field Level Communication (FLC) initiative, as well as the announcement of a globally available OPC UA Cloud Library.

The purpose of the FLC initiative is to develop a general model of OPC UA architecture for use by technology suppliers in their automated field devices. The first set of OPC UA Field eXchange (OPC UA FX) specifications were announced at the SPS event in 2019. The newly released second set of specifications consists of four parts and focuses on enabling communication between automation components using both OPC UA client/server and publish/subscribe methodologies.

Those four parts:

  • Provide an overview and introduce the basic concepts of using OPC UA for field level communications.
  • Specify the base information model and communication concepts to meet the various use cases and requirements of factory and process automation.
  • Describe networking services, such as topology discovery and time synchronization.
  • Describe the data structures for sharing information required for offline engineering using descriptors and descriptor packages.

The OPC Foundation created a multi-vendor interoperability demo that uses components from 20 different manufacturers to illustrate the functionality of the new specifications. Focusing on horizontal forms of communication, such as controller-to-controller, the demo shows how process data is exchanged via UDP/IP using wired Ethernet or Ethernet TSN (time-sensitive networking), as well as in combination with a 5G wireless connection.

Cloud library

The OPC UA Cloud Library, developed in partnership with the Clean Energy and Smart Manufacturing Innovation Institute (CESMII) was also announced at the event. Drawing on contributions from all major cloud vendors, the cloud library contains 65 OPC UA information models.

   Read about other collaborative initiatives involving CESMII.

According to the OPC Foundation, this library allows applications to more easily access OPC UA information models and reportedly increases overall ease-of-use for end-users by making the entire collection of OPC UA companion specifications more widely available. While assets at the operations technology level are already able to access these information models from other devices and pieces of equipment, security concerns have limited the degree to which they can be delivered via the cloud. However, through the OPC UA Cloud Library, this difficulty can be surmounted.

Erich Barnstedt, chief architect for standards and consortia at Microsoft and chair of the OPC UA Cloud Library working group, explained how this new cloud library helps address security concerns. "The OPC UA Cloud Library is the missing link that makes OPC UA information models available in the cloud on a global scale without requiring a connection to physical machines," he said. "It enables OPC UA information models that are used as blueprints for industrial digital twins to be looked up and matched against time-series machine telemetry data provided by cloud-based analytics software, which is a common requirement in IIoT projects."

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