n OPC requires a complex DCOM configuration.n OPC requires separate complex firewall settings.n Scalable and platform-independent communication standard specified in IEC 62541.n Standardization of classic OPC specifications with integrated security concept.n The OPC UA security concept includes user and application authentication, messagesigning, and encryption of transmitted data.n IP-based, optimized, binary protocol for Internet and firewall communication via oneport (4840).n With OPC UA, any type of information is available at any time and place for anyauthorized application and authorized person. For example, raw data and prepro-cessed information can be transported safely from the sensor and field level to thecontrol system and into the production planning systems.n SOA (Service Oriented Architecture) replaces the Microsoft DCOM technology withopen, platform-independent protocols with integrated security mechanisms.– Communication takes place via standardized services based on the Informationmodel of OPC UA.– The services are divided into different task groups.– Based on a basic model, arbitrarily complex, object-oriented extensions of theservices can be carried out, without affecting interoperability.n An OPC UA server provides information within a network that can be retrieved froman OPC UA client.n The data exchange can take place via security certificates, which have to be storedaccordingly in the server.n The OPC UA server provides basic services such as data exchange or navigationthrough the address space.n The OPC UA configuration is used to define the variables or contents that anOPC UA server should provide.n The OPC UA configuration is done via an external tool such as for CPUs from VIPAthe OPC UA Configurator from VIPA.OPC UA clients are programs with the following functionality:n Read or write access to information of the OPC UA server.n Access is controlled by access rights.n Execute services on the OPC UA server.n Client/Server– An OPC UA client accesses information from the OPC UA server via services,provided by the OPC UA server. Here a fix defined connection is used.– Example: OPC UA client retrieves status of an input in the CPU.n Publisher/Subscriber– A Publisher sends to unknown Subscriber (clients) without a fixed connection.– Example: Sensors send data to the cloud.7.2.2 Information modelingn Information models are used to describe devices and their data.n The basis is the Core specification. The Core specification describes the structure ofthe address range and of the services, such as the entry points for the clients in theaddress space of an OPC UA server.OPC UA - Open PlatformCommunications UnifiedArchitectureOPC UA serverOPC UA clientCommunication typesInformation modelVIPA System SLIO Deployment OPC UABasics OPC UA > Information modelingHB300 | CPU | 013-CCF0R00 | en | 19-30 185
