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Softing New Automation Concepts with OPC Unified Architecture

by VDE Verlag, etz, ed. 4-2011Page 1 of 3

Fig. 1. OPC UA allows multiplatform communication betweenapplications

New Automation Concepts withOPC Unified ArchitectureJrgen Lange, Softing Industrial Automation GmbH

The OPC UA technology complements the traditional OPC industrial standard byadding important characteristics such as platform independence, scalability, highavailability, and Internet capability. Many automation component vendors already offer

OPC UA clients or servers for their PLCs, process control systems, field devices, oroperator panels. An efficient and cost-effective way to develop conformant OPC UAproducts is to use OPC development kits like, for example, Softing's OPC UA toolkit.

OPC technology has evolved intoa de-facto standard for interope-rable data exchange betweenmulti-vendor software applicationsthat is applicable in a wide rangeof industries spanning from manu-facturing and process industries tobuilding automation and manyothers. Today more than 20,000OPC products from over 3,500different manufacturers are in useall over the world. OPC facilitatesthe data transfer between widelydistributed parts of a plant. TheOPC interfaces bridge the dividebetween heterogeneous automa-tion worlds.

With the introduction of theplatform-independent OPC UnifiedArchitecture (OPC UA), OPC tech-nology has started to conquer new

application areas, such as embed-ded systems or the IT world.Recently, the new technology hasestablished itself in areas whereOPC was hardly seen before, e.g.device parameterization. Thereason for this breadth of appli-cation is that the OPC UA tech-nology offers extended featureswhen compared to Classic OPC.OPC UA's platform independenceand, in particular, its scalabilityopens up many possibilities fornew and efficient automation

concepts.

Standardized communication

OPC UA facilitates the secure,reliable, and manufacturer-inde-pendent transport of raw data andpre-processed information from thefactory floor to the production plan-

ning or ERP system. The desiredinformation is provided to anyauthorized application and person,anytime and anywhere. This func-tionality is independent of themanufacturer that created theapplications, the programminglanguage they were developed in,and the operating system they runon. OPC UA is no longer DCOMbased, but uses a service-orientedarchitecture (SOA). This makesOPC UA easy to port. Today,OPC UA builds a bridge betweenthe enterprise level with Unixsystems and embedded auto-mation components running differ-

ent versions of Windows and non-Windows operating systems(Fig. 1).

OPC UA provides a set of featuresthat allows the implementation ofnew concepts for secure and

robust plant automation. Theyinclude:

Standardized communicationover the Internet and acrossfirewalls:OPC UA uses a dedicated UABinary protocol for data ex-change that is based on TCP;Web services and HTTP are alsosupported. Only one port needsto be opened in a firewall that'senough. Integrated securitymechanisms guarantee secure

Internet communication.

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Fig 2. OPC UA allows secure and robust information permeability from the sensor to the ERP systemFig 2. OPC UA allows secure and robust information permeability from the sensor to the ERP system

Protection against unauthorizeddata access:The sophisticated securityconcept provided by OPC UAtechnology ensures efficientprotection against unauthorizedaccess, sabotage, and faults

caused by negligent use.OPC UA security is based onglobal standards developed bythe World Wide Web consortium.It offers various possibilities toidentify applications, authenticateusers and protect against unau-thorized access, as well as signmessages and encrypt thepayload transferred.

Data security and reliability:The communication standarddefines a robust architecture with

reliable communication mecha-nisms, configurable timeouts,automatic fault detection, andrecovery mechanisms. Thecommunication link between aOPC UA client and server can bemonitored by both the client andthe server. If a connection istemporarily interrupted, the datacan be buffered in the server. Insecurity-critical areas, OPC UAdefines an additional redundancyconcept that can be used fordevices, servers and clients.

Platform independence andscalability:Using service-oriented basetechnologies ensures thatOPC UA is platform independentand opens up many possibilitiesfor new and cost-effective auto-mation concepts. Embeddedfield devices, process controlsystems, PLCs, gateways, oroperator panels are developedusing lean OPC UA server im-plementations that have beenported directly to operating

systems including embeddedLinux, VxWorks, QNX, RTOS,and many more.

Simplification by unification:OPC UA defines an integratedaddress space and an informa-tion model that maps processdata, alarms, historical data, andprogram invocations. In this way,even complex processes can befully described with OPC UA.While classic OPC requires threedifferent OPC servers DA, AE

and HDA with different seman-tics to acquire, for example, thecurrent value of a temperature

sensor, the event of excess tem-perature, and the historical aver-age temperature, OPC UA needsonly one component. This helpsto reduce configuration andengineering times.

High performance:

OPC UA is based on a binaryprotocol that is TCP-based. Thisvery efficient protocol allows fora fast data exchange that willmeet the high-performancerequirements of most applica-tions. The actual binary protocolimplementation is availablethrough the OPC Foundation andserves as the basis for allOPC UA servers and clients.

New application possibilities:The wide breadth of the

OPC UA technology allows im-plementing new vertical integra-tion concepts. By cascadingOPC UA components, informa-tion can be transported securelyand reliably from the factory floorall the way up to the productionplanning or ERP system (Fig. 2).For this purpose, OPC UAenabled client and server com-ponents at the automation levelconnect embedded UA serversat the field level with OPC UAclients integrated in ERP

systems at the enterprise level.The individual OPC UA compo-nents can be geographically

distributed and separated fromeach other by firewalls withoutproblems.

Developing OPC UA basedconcepts

Many automation componentvendors already offer OPC UAclients or servers for their PLCs,process control systems, fielddevices, or operator panels. Anefficient and cost-effective way tobuild OPC UA components is torely on conformant OPC toolkits,such as the OPC Toolbox UA(Fig. 3) from Softing [1]. Thissoftware allows the quick and easydevelopment of OPC UA clientsand servers for Windows, Linux,VxWorks and other embeddedoperating systems. OPC UA

specific functionality for creating,browsing, and managing anOPC UA address space; forcreating, deleting, reading, andwriting OPC UA objects; for eventhandling, method calls, and muchmore has been fully implementedin the compact OPC Toolbox UA.

With the toolbox, developers cansave several months of time andreduce the time-to-market for theirproducts.

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Fig. 3. OPC UA toolkits comprising platform dependent and platform independentparts allow implementing OPC UA clients and servers on almost any targetplatform

Conclusion

The future IEC communicationstandard OPC UA providesfeatures that offer new possibilitiesof embedding an internationallystandardized communicationinterface in disparate systemsranging from PLCs, process controlsystems, drives, gateways andoperator panels to MES or ERPsystems. The result is savings ininstallation, setup, commissioning,maintenance and operation. Com-munication structures can besimplified and vertical integrationconcepts consistently imple-mented. Toolkits like the OPCToolbox UA allow the cost-effectiveand efficient implementation ofOPC UA components underWindows and in embeddedsystems.

Bibliography

[1] Softing Industrial AutomationGmbH, Haar, Germany:www.softing-ia.com

by VDE Verlag. This article was

published in the German trademagazine etz, ed. 4-2011

Dipl.-Ing. Jrgen Lange is Market Segment Managerat Softing Industrial Automation. He also represents

the company at OPC Europe and at the TechnicalAdvisory Council of the OPC Foundation.

E-Mail: [email protected]

fae jl opcua 2011 04 etz

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