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Industrial Ethernet Book 105

4.2018 industrial ethernet book Time synchronization in IEC 61850 substations under control! The most comprehensive range of advanced IEC 61850 and IEEE 1588 testing tools for substations and laboratories. OTMC 100p IEEE 1588/PTP Grandmaster Clock TICRO 100 IEEE 1588/PTP Time Converter www.omicron-lab.com/timing DANEO 400 IEC 61850 Signal Recorder & Analyzer EMCON 200 PTP-Transparent Media Converter www.omicronenergy.com/puc to assign preconfigured addresses. DNS (server): DNS is a mechanism to resolve descriptive names (i.e. host names) to IP addresses. All higher layer protocols and services, including engineering and configuration tools, can then use the easierto remember host names. Grandmaster clock The term originates from the IEEE 1588 standard for precise clock synchronization and has been adopted by IEEE 802.1AS. It refers to the most precise clock device in the network with master capabilities. It will either be selected automatically as the time master for the network by the Best Master Clock Algorithm (BMCA). Or, in .1AS, the clock hierarchy can also be predefined. OPC UA GDS The Global Discovery Server (GDS) of OPC UA is responsible for enterprise-wide administration of OPC UA servers. It fosters discovery via lists of “capabilities” and addresses, creates and distributes application certificates for secure connections. Directory services (optional) Such IT services (e.g. Microsoft’s Active Directory) are used for enterprise-wide asset, user and role management including personal data, access rights (to files, programs), certificate management and much more. Utilizing these in an OT environment constitutes a quick win in terms of organizational efficiency. TSN CUC The Central User Configuration (CUC) is a role defined in the IEEE 802.1Qcc standard with the task of configuring the end nodes (or their applications – the users of the network). This includes network configuration, for which it communicates with the CNC. PTCB The OPC UA Pub/Sub TSN Configuration Broker (PTCB) is a OPC UA standardized implementation of the CUC functionality. The PTCB forwards the requirements to the CNC, which schedules the streams and reports the result back to the PTCB. Finally, the PTCB reports back to the end station on how to use the scheduled streams. TSN CNC The Central Network Configuration (CNC) has two primary tasks: (i) calculating the network schedule and (ii) distributing the parameters of the network schedule to the infrastructure components (Ethernet switches). For the latter to support interoperability, the selection of the protocol is critical. As of today, NETCONF is the technology of choice because of its wide availability, technical maturity and the possibility to manipulate a shadow configuration. New device roles The following is a list of logical functions in a network inspired by today’s fieldbus architectures. Implementation of these roles is not strictly mandatory in order to operate an OPC UA TSN network. Without them, however, booting and operating a network would require frequent, substantial manual intervention. All device roles are vendor independent and thus interoperable. Application slave This is the role with the greatest number of instances. It basically features a state machine to manage its operation mode and some functions for remote configuration. Examples are I/Os, drives and valves. Application master The role for PLCs or Edge Controllers in a classic fieldbus network. From the perspective of network infrastructure, there is no difference between application slave and application master. In terms of computational performance, application features and TSN features, however, may differ considerably. Configuration server This can be seen as a (distributed) database containing version-controlled and signed binary artifacts used for firmware and configuration. The content of the files is vendor-specific and can be anything that should reside on a device – from bitstreams for FPGAs, compiled application code and configuration files to images, data sheets and maintenance videos. Network manager This role connects to the engineering tool and holds all the information about distribution of the application. The network manager guides all devices through the start-up process and triggers required actions like address assignment and firmware/configuration update. User roles In addition to the device roles (representing “users” on the network authorized to perform certain management functions like upgrading a device’s firmware), a set of predefined user roles for human interaction with the network should be available, like Administrator, User, and Maintenance. Security and certificates Security has the potential to be one of the key distinguishing features between OPC UA TSN and legacy fieldbus systems, since it cannot be just added to a system. An international


Industrial Ethernet Book 105
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