Digital Factory Superstructure Emerging with OPC UA

  • February 17, 2012
  • Feature
February 2012
By Bill Lydon, Editor
OPC UA is emerging as a fundamental technology for implementing Digital Factory concepts to increase production efficiency. This was reinforced at a half day session during the Sixteenth Annual ARC World Industry Forum Conference on February 9, 2012, organized by ARC and Tom Burke, President of the OPC Foundation. The session titled, Transforming Manufacturing with OPC UA: From Embedded to the Enterprise, featured a number of presentations reinforcing the value of OPC UA.
OPC UA technology provides an efficient and secure infrastructure for communications from sensor to business enterprise computing for all automation systems in manufacturing and process control. OPC UA is leveraging the accepted international computing standards putting automation systems on a level playing field with the general computing industry. OPC UA uses common computing industry standard Web Services which are the preferred method for system communications and interaction for all networked devices.   The World Wide Web Consortium (W3C) defines a Web Service as "a software system designed to support interoperable machine-to-machine interaction over a network.” This is precisely the task of automation systems.
Bridging Business & Real Time
Dennis Brandl, BR&L Consulting, discussed the OPC UA/ISA95 Companion Specification being developed based on the B2MML interface standards. He commented, “I am really glad that the OPC Foundation has picked this up and we have a couple of vendors helping work on this…” The new OPC-UA/ISA95 Specification and implementations will allow real time access to critical data serving as a bridge between the slow speed and occasional access requirements of corporate systems and high speed requirements of Manufacturing Operations Management (MOM) systems.  The OPC UA/ISA95 companion specification provides a standard means to bridge the enterprise with various automation systems including WMS, LIMS, MES, and Asset management systems. Brandl noted, “This is will drive integration costs down and improve production operations in a much more efficient manner.” Dennis Brandl has been involved in MES, batch control, and automation system design and implementation in a wide range of applications over the past 30 years and has been an active member of ISA’s SP95 Enterprise/Control System Integration committee from the beginning. 
Brandl explained that the OPC UA/ISA95 Companion Specification companion standard will take various pieces of the ISA95 model, based on the B2MML schemas, to define object models for information interchange using OPC UA. B2MML is an XML implementation of the ANSI/ISA 95 family of standards known internationally as IEC/ISO 62264.   B2MML consists of a set of XML schemas written using the World Wide Web Consortium's XML Schema language (XSD) that implement the data models in the ISA95 standard ( Brandl noted, “B2MML has been heavily used for the past 5-6 years at least to do integration between business level systems and the shop floor systems.” 
Brandl described a typical situation where a vendor in the supply chain communicates to the plant’s business system.  The example situation is - putting a hold on a production lot of material already shipped to the plant due to discovery of a supplier problem. This information needs to be conveyed to the shop floor systems immediately to make “just in time decisions” to avoid manufacturing defective product resulting in scrap losses. Another example situation is the communication of production equipment status to business systems so adjustments can be made as equipment goes out of service to modify manufacturing routings and optimize production efficiency. The new linkages created by the marriage of OPC UA/ISA95 standardize and simplify these communications.
Any company may use B2MML Schemas royalty free and can download B2MML Schemas.
Enterprise Integration
Reiner Bildmayer of SAP Research at SAP AG ( discussed the evolution of ERP systems driving the need for OPC UA as a modern mechanism for linking the plant floor to the enterprise. SAP Research is the global technology research unit of SAP, with a network of 19 research locations worldwide covering a portfolio of seven research practices. SAP Research has established a worldwide collaborative network with more than 800 partners from industry and academia. SAP Research’s own network consists of 500 employees (including PhD candidates) across five continents. Bildmayer is deeply involved with SAP’s PLANTCockpit project. Bildmayer described the value of the direct linkage provided by OPC UA to the enterprise and noted, “OPC UA for ERP fits perfectly because today’s manufacturing companies’ survival will not be supported any longer by ERP systems from 3 decades ago.” 
OPC UA from a User’s Perspective
Clinton Chapman, Drilling Automation Program Architect at Schlumberger, discussed OPC UA from a user’s perspective.   He is also the Deputy Chairman and leader of the Comms Team for the Society of Petroleum Engineers ( Drilling System Automation (DSA-TC) Technical Section.   The objective of this group is to accelerate the uptake of drilling systems automation by supporting initiatives that communicate the technology, standardize its nomenclature, promote lessons learned/best practices, and help define its value proposition. They are using OPC UA as part of this initiative and have completed a successful demonstration proving the value of OPC UA for drilling automation.  OPC UA allows the many organizations involved in drilling automation to have common communications. Chapman noted that OPC UA was chosen because of a push from Shell and general agreement that the OPC Foundation was a strong organization with broad industry support. 
PLC Programming Integration
PLCopen has an OPC UA function block standard as an extension to IEC 61131-3, developed from collaboration between the OPC Foundation and PLCopen (   The OPC UA function block standard encapsulates mapping of the IEC 61131-3 software model to the OPC UA information model and provides a standard way for OPC UA server-based controllers to expose data to OPC UA clients including HMIs, MES, LIMS, ERP and other systems.   The first step was demonstrated at the 2009 SPS/IPC/Drives Conference in Nuremberg, Germany. More Information.
Thoughts & Observations
Most everyone agrees that achieving more efficient and responsive production requires integration of business systems with industrial automation systems. The big question has always been how to make it happen? OPC UA on its own provides a great way to bridge the gap. Using OPC UA to implement the vision of ISA95 down to the automation level really completes the picture.
Based on my experience and observations, the integration of manufacturing and business systems has been a labor intensive task with the creation of custom programs that require a great deal of ongoing support. OPC UA provides an efficient standard linkage between the control loop and information loop that simplifies this process.
OPC UA brings the digital plant into focus and out of the dark ages into open computing industry standards.

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