The OPC Foundation continues to grow in popularity. As of 24 April, the organization has 602 member companies - and the trend is rising. When announcing new developments, Stefan Hoppe quickly moves on to one of the most important topics that has been implemented: In February, the OPC Foundation released Part 14 of the OPC UA standard: known as Publish-Subscribe or 'PubSub' for short. The specification expands the scope of OPC UA to include a wide range of additional use cases down to the lowest field level.

Stefan Hoppe: "The new PubSub extension takes the OPC UA Eco system to a new level."

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In addition to the existing request/response procedure, which requires a 'standing' connection between OPC client (data consumer) and OPC server (data provider), there will be another communication mechanism based on the publish-subscribe principle in the future. This will allow OPC UA to be used in other application areas. For example, in sensor networks and cloud applications, a large number of devices typically send their data to one recipient (many-to-one). With the publish-subscribe method, a publisher (OPC server) sends its data into the network without a connection and many subscribers (clients) can receive this data without the need for a resource-intensive connection. In the Industrial Internet of Things (IIoT) and also in Industry 4.0 applications, communication can be realized via brokers in the cloud. Here, many hundreds or even thousands of devices can publish information and subscribers receive the messages from the broker in the cloud. Standard protocols such as AMQP and MQTT are used for this. In addition to a sensor or cloud connection in a many-to-one scenario, connectionless pub/sub communication offers further advantages. In local communication between known participants, such as industrial control systems, only small amounts of data often need to be transferred. In many cases, response times must be guaranteed and thus deterministic real-time requirements must be met. To achieve this, pub/sub communication is to be combined with the new Ethernet extensions for Time Sensitive Networks (TSN). Real-time communication between controllers from different manufacturers is then possible via TSN-capable network components (switches).

According to Stefan Hoppe, the first PubSub implementations could be realized in 8-bit controllers with only 2 kByte SRAM.

Euromap 77

Regulating the exchange of data between injection molding machines and host computers or MES - that is the aim of the newly published Euromap 77 standard. Specifically, Euromap 77 is the first OPC UA-based standard for digital interfaces in the field of plastics and rubber machines. Euromap 77 was published on May 4 and is available for download at http://www.euromap.org.

In order to increase production efficiency, more and more plastics processors worldwide are relying on the digital networking of machines and components. Equipment from different manufacturers is used in most production facilities. If the processor can rely on standardized interfaces for networking, the high configuration effort involved in adapting individual solutions is eliminated. Euromap, the European Committee of Plastics and Rubber Machinery Manufacturers, is developing these standards for cross-manufacturer communication based on OPC UA. OPC UA enables communication between acting and sensing systems and is therefore an important component of Industry 4.0," confirms Jonas Schwarz, Product and Technology Manager at Krauss Maffei.

Compared to its predecessor Euromap 63, the Euromap 77 standard offers an extended range of functionalities. With Euromap 77, machines from different manufacturers can be networked with significantly less effort, for example for monitoring, process data acquisition or job management. Prototype implementations of the release candidate have been available since spring 2018: The standard was tested during two plugfests by the companies involved in its development.

Companion specs for drives

The VDMA is currently working hard on Companion Specifications, so-called information models for products and their capabilities. The latest activity in this regard: The Industry 4.0/OPC UA Drive Technology working group started developing OPC UA Companion Specifications for drive technology on April 17. The OPC UA communication architecture serves as the basis for this. As an essential component of many machines and systems, drives determine their costs, energy efficiency and optimization potential in many ways. Intelligent drive components form an active part of Industry 4.0 applications and processes and are therefore the basis for networked services and business models of the future.

For this reason, the new VDMA Industry 4.0 / OPC UA Drive Technology working group has set itself the task of developing manufacturer-independent OPC UA Companion Specifications for the drive system - including the transmission elements. In order to dovetail with existing, relevant activities, the working group is in close coordination with industry-specific OPC UA committees. As an important additional step, the working group plans to join forces with the OPC Foundation as a Joint Working Group.