IEC PAS 62408:2005 pdf download Real-time Ethernet Powerlink (EPL)
1.1 Scope and general description
ETHERNET Powerlink (EPL) is a communication profile for Real-Time Ethernet (RTE). lt extendsEthernet according to the lEEE 802.3/1SO/IEC 8802-3 standard with mechanisms to transfer data withpredictable timing and precise synchronisation. The communication profile meets timing demandstypical for high-performance automation and motion applications. lt does not change basic principlesof the Fast Ethernet Standard lEEE 8023 but extends it towards RTE. Thus it is possible to leverageand continue to use any standard Ethernet silicon, infrastructure component or test and measurementequipment like a network analyzer.
1.1.1 Slot Communication Network Management(SCNM)
EPL provides mechanisms to achieve the following:
Transmit time-critical data in precise isochronous cycles. Data exchange is based on apublish/subscribe relationship. lsochronous data communication can be used for exchangingposition data of motion applications of the automation industry.Synchronize networked nodes with high accuracy.20Transmit less time-critical data asynchronously on request. Data exchange is based on a pointo-point relationship. Asynchronous data communication can be used to transfer lP-basedprotocols like TCP or UDP and higher layer protocols such as HTTP, FTP,…EPL manages the network traffic in a way that there are dedicated time-slots for isochronous andasynchronous data. lt takes care that always only one networked device gains access to the networkmedia. Thus transmission of isochronous and asynchronous data will never interfere and precisecommunication timing is quaranteed. The mechanism is called Slot Communication NetworkManagement (SCNM) SCNM is managed by one particular networked device – the Managing Node(MN) – which includes the MN functionality. All other nodes are called Controlled Nodes (CN).
1.1.2 EPL key features
EPL provides the following key features:
• Ease-of-Use to be handled by typical automation engineers without indepth Ethernet network knowledge.
• Up to 240 networked real-time devices in one network segment
• Deterministic Communication Guaranteed
o IAONA Real-time class 4 (highest performance)
o Down to 200µs cycle times
o Ultra-low jitter (down to <1µs) for precise sycnhronisation of networked devices • Standard Compliant o IEEE 802.3u Fast Ethernet o IP based protocols supported (TCP, UDP,...) o Integration with CANopen Profiles EN 50325-4 for device interoperability o Implementation based on standard Ethernet Chips- No special ASICs necessary • Direct peer-to-peer communication of all Nodes (Publish/subscribe) • Hot Plugging • Seamless IT-Integration – Routing of IP protocols EPL is based on the ISO/OSI layer model and supports Client/Server and Producer/ Consumer communications relationships. The ETHERNET Powerlink Standardization Group (EPSG) is working closely with the CiA (CAN in Automation) organisation to integrate CANopen with EPL. CANopen standards define widely deployed communication profiles, device profiles and application profiles. These profiles are in use millions of times all over the world. Integration of EPL with CANopen combines profiles, high performance data exchange and open transparent communication with TCP/UDP/IP protocols.

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