Industrial Ethernet Technologies Page 1 © EtherCAT Technology Group, August 2011 Industrial Ethernet Technologies: Overview Classification Profinet Ethernet/IP CC-Link IE Sercos III Powerlink Modbus/TCP EtherCAT Summary © EtherCAT Technology Group Industrial Ethernet Technologies Editorial Preface: This presentation intends to provide an overview over the most important Industrial Ethernet Technologies. Based on published material it shows the technical principles of the various approaches and tries to put these into perspective. The content given represents my best knowledge of the systems introduced. Since the company I work for is member of all relevant fieldbus organizations and supports all important open fieldbus and Ethernet standards, you can assume a certain level of background information, too. The slides were shown on ETG Industrial Ethernet Seminar Series in Europe, Asia and North America as well as on several other occasions, altogether attended by several thousand people. Among those were project engineers and developers that have implemented and/or applied Industrial Ethernet technologies as well as key representatives of some of the supporting vendor organizations. All of them have been encouraged and invited to provide feedback in case they disagree with statements given or have better, newer or more precise information about the systems introduced. All the feedback received so far was included in the slides. You are invited to do the same: provide feedback and – if necessary – correction. Please help to serve the purpose of this slide set: a fair and technology driven comparison of Industrial Ethernet Technologies. Nuremberg, August 2011 Martin Rostan, [email protected] Industrial Ethernet Technologies Page 2 © EtherCAT Technology Group, August 2011 Industrial Ethernet Technologies: Overview Classification Profinet Ethernet/IP CC-Link IE Sercos III Powerlink Modbus/TCP EtherCAT Summary © EtherCAT Technology Group Industrial Ethernet Technologies All Industrial Ethernet Technologies introduced in this presentation are supported by user and vendor organizations. EPSG and ETG are pure Industrial Ethernet organizations, whilst the others have a fieldbus background and thus members primarily interested in the respective fieldbus technology. All technology names as well as the names of the organizations promoting and supporting those are trademarked. The trademarks are honored. Page 3 © EtherCAT Technology Group, August 2011 Basic Slave Device Approaches Classification Profinet ITApplics Principle applied by: Ethernet/IP • SNMP (CbA) Sercos III • DHCP Layer 5..7 •… Hardware Modbus/TCP and Real-Time Data Automation API TCP/UDP Layer 4 Powerlink Application Parameter-Data • HTTP Software CC-Link IE A • Completely TCP/UDP/IP based • Ordinary Ethernet Controllers and Switches Layer 3 IP Layer 1+2 Ordinary Ethernet Controller Slave Device Architecture Industrial Ethernet Technologies EtherCAT Summary © EtherCAT Technology Group Industrial Ethernet Technologies Depending on the real time and cost requirements, the technologies follow different principles or approaches. This comparison tries to group those approaches in three different classes by looking at the slave device implementations: Class A uses standard, unmodified Ethernet hardware as well as standard TCP/IP software stacks for process communication. Of course some implementations may have modified „tuned“ TCP/IP stacks, which provide better performance. Class A approaches are also referred to as „best effort“ approaches. The real time performance is limited by unpredictable delays in infrastructure components like switches – no just due to other traffic on the network. The by far largest obstacle to better real time performance however is provided by the software stacks (TCP/UDP/IP). Page 4 © EtherCAT Technology Group, August 2011 Basic Slave Device Approaches Classification Profinet • Process Data: Parallel Channel to TCP/UDP/IP • TCP/UDP/IP Timing Controlled by Process Data Driver • Ordinary Ethernet Controllers and Switches (or Hubs) ITApplics CC-Link IE (RT) Software Ethernet/IP Sercos III Application • HTTP Parameter Process • SNMP Data Data • DHCP Layer 5..7 Layer 4 Automation API •… TCP/UDP IP Powerlink Hardware Layer 3 Modbus/TCP Layer 1+2 B Process Data Protocol Timing-Layer Ordinary Ethernet Controller Slave Device Architecture Industrial Ethernet Technologies EtherCAT Summary © EtherCAT Technology Group Industrial Ethernet Technologies Class B approaches still use standard, unmodified hardware, but do not use TCP/IP for process data communication. A dedicated process data protocol is introduced, which is transported directly in the Ethernet frame. TCP/IP stacks may still exist, but typically their access to the Ethernet network is controlled and limited by what can be considered a timing layer. Of course this description is pretty generic – but more details are given in the technology specific sections. Page 5 © EtherCAT Technology Group, August 2011 Basic Slave Device Approaches Classification Profinet • Process Data: Parallel Channel to TCP/UDP/IP • TCP/UDP/IP Timing Controlled by Process Data Driver • Special Realtime Ethernet Controllers or Switches ITApplics CC-Link IE (IRT) Software Ethernet/IP Sercos III Application • HTTP Parameter Process • SNMP Data Data • DHCP Layer 5..7 Layer 4 Automation API •… TCP/UDP IP Powerlink Hardware Layer 3 Modbus/TCP Layer 1+2 C Process Data Protocol Timing-Layer Special Realtime Ethernet Controller Slave Device Architecture Industrial Ethernet Technologies EtherCAT Summary © EtherCAT Technology Group Industrial Ethernet Technologies Class C approaches aim even higher with regard to performance. In order to achieve these goals, dedicated hardware has to be used (at least on the slave device side). In case of Profinet IRT, the Special Real-time Ethernet Controller is more a Special Switch Device – but the result is the same: better performance due to better hardware integration. This does not exclude the use of TCP/IP and the Internet Technologies. Industrial Ethernet Technologies Page 6 © EtherCAT Technology Group, August 2011 PROFINET Overview Classification Profinet PROFINET – PI / Siemens Ethernet Solution Three different varieties: Version 1 (2001) CbA: Ethernet/IP A „Component based Automation“ Version 2 (2004) RT: Version 3 (2005) B Soft Real Time (Software Based) CC-Link IE IRT: C Isochronous Real Time (Hardware Based) Sercos III Powerlink Modbus/TCP EtherCAT Summary Pictures sourced from PTO/PNO website © EtherCAT Technology Group There are 3 PROFINET-Versions: Version 1 („Component Based Automation“), a Class A approach Version 2 ((Soft) Real Time“), a Class B approach Version 3: („Isochronous Real Time“), a Class C approach Profibus International (PI) tries to move away from the terms RT/IRT and introduced the term Profinet IO for both RT and IRT… Industrial Ethernet Technologies Page 7 © EtherCAT Technology Group, August 2011 PROFINET Performance Classification Profinet Communication cycle time + Jitter PROFInet PROFInet V3.0 (IRT) V2.0 (SRT) PROFInet V1.2 (TCP/ IP) Ethernet/IP CC-Link IE C B A Sercos III Powerlink 15% Modbus/TCP EtherCAT 0,25...1,0 msec 10 msec* 100% t 100 msec * Depending on configuration, 1 ms has been demonstrated Summary Pictures sourced from PI website © EtherCAT Technology Group Not all IRT devices support cycle times < 0.5 ms, e.g. Siemens Sinamics Controller. Industrial Ethernet Technologies Page 8 © EtherCAT Technology Group, August 2011 PROFINET V1 (CbA) Classification Profinet Ethernet/IP CC-Link IE Sercos III • Initial Profibus Answer to the Ethernet Hype: Profinet V1 • Remote Procedure Calls on TCP/IP originally using DCOM • Access to Profibus Networks via Proxy Devices • For Parameter Data only, not for Process Data • since DCOM will not be advanced by Microsoft any more, Profinet CbA V2 has SRT Protocol Adaptation • few known Products. Engineering, HMI Internet Powerlink Modbus/TCP EtherCAT A Automation device Engineering, HMI TCP/IP- Ethernet Intelligent field device Proxy PROFIBUS Intelligent drive Summary Pictures sourced from PI website Automation device Field device Drive © EtherCAT Technology Group Initially the PNO/PTO message was: protect your investment and continue using Profibus, for Ethernet connectivity we provide a transparent gateway. Work on the gateway (proxy) concept was started as early as 1999. First spec (V0.9) published in March 2001 (Ethernet/IP was first introduced in 2000). Industrial Ethernet Technologies Page 9 © EtherCAT Technology Group, August 2011 Component Based Programming Approach Engineering Interface Classification Data Interface Profinet Information Ethernet/IP Vendor A Bottle Cleaning Vendor B Filling CC-Link IE PROFIBUS • PROFINET CbA comprises more than just the communication • Approach may be fine for 50 variables, but how do you handle 500 variables this way? PROFIBUS PROFInet Connection Editor Sercos III Powerlink Modbus/TCP Bottle Cleaning Filling EtherCAT Summary © EtherCAT Technology Group Industrial Ethernet Technologies Pictures sourced from PI website Profinet CbA (Component Based Automation) comprises more than just a communication protocol: the CbA programming approach with graphical mapping of variables to establish communication links. Industrial Ethernet Technologies Page 10 © EtherCAT Technology Group, August 2011 PROFINET V2 (RT) Classification Profinet Ethernet/IP CC-Link IE Sercos III Powerlink Modbus/TCP EtherCAT Originally named „Soft Realtime“ (SRT) B „Best Effort“ Protocol with 5 .. 10 ms typical cycle time and 15% jitter Modified Stack bypasses TCP and IP for Realtime-(process)data Aimed at and suited for PLC type applications (including drive control, but not motion control) • Requires substantial amount of software (Field device: ~ 1MByte) Limitations: • Soft Realtime Solution with • • • • – Influence by TCP traffic – Inpredictable Queue delays in switches – Stack delays • Standard Controllers are sensitive for IP Multicast Traffic Summary Pictures sourced from PI website © EtherCAT Technology Group Industrial Ethernet Technologies Profinet V2 was initially called SRT (Soft Real-time). The term „soft“ was later dropped for marketing reasons. Profinet RT is also addressed as Profinet I/O (together with IRT). Siemens has started to communicate that Profinet RT will provide similar performance as Profibus. Even though this is optimistic (typically Profibus is faster and provides better node synchronization), one can read this statement as follows: If Profibus performance is sufficient, but Profibus is not expensive enough, Profinet RT is an alternative ;-) Industrial Ethernet Technologies Page 11 © EtherCAT Technology Group, August 2011 PROFINET V2 (RT) and V3 (IRT) Classification Profinet Ethernet/IP CC-Link IE Sercos III Powerlink Modbus/TCP V2 Real-Time (RT) • Software Solution with Standard Controller • Usage of Standard Network Components • Real-Time as good as provided by – Switching Technology – VLAN-Tagging (Prioritization, IEEE802.1q) V3 Isochronous Real-Time (IRT) • Synchronization of all nodes • Bandwidth reservation for isochronous Data • Requires Special Hardware ASIC B C EtherCAT Summary © EtherCAT Technology Group Industrial Ethernet Technologies Profinet IRT is a class C approach which introduces special hardware in order to achieve sufficient performance and synchronicity for motion control applications. Industrial Ethernet Technologies Page 12 © EtherCAT Technology Group, August 2011 PROFINET V3 (IRT) Features Classification Profinet Ethernet/IP CC-Link IE Sercos III • • • • Timeslicing Approach by special Switch ASICs C Switches can be integrated into devices Topologies: Line (up to 25 nodes), Branch, Tree supported Cycle Time 250 µs to 4 ms, 1 µs jitter IRTchannel (TCP/IP) Cycle 1 IRTchannel (TCP/IP) Cycle 2 Cycle n Powerlink e.g. 1 ms position control loop Modbus/TCP EtherCAT Synchronization Deterministic communication IRT- Data Summary open communication TCP/IP- Data Pictures sourced from PI website © EtherCAT Technology Group Industrial Ethernet Technologies The minimum cycle time is determined by the approach to include generic TCP/IP traffic in a gap wide enough for the largest Ethernet frame. This approach leads to limited bandwidth utilization, since even though most applications only have sporadic TCP/IP communication, the bandwidth remains reserved for this kind of traffic. Even though the specification allows for cycle times starting from 250µs, some Siemens IRT master devices only support cycle times starting from 500 µs. Industrial Ethernet Technologies Page 13 © EtherCAT Technology Group, August 2011 PROFINET V2 (RT) and V3 (IRT) Classification Profinet Ethernet/IP CC-Link IE Sercos III Both versions can be mixed, if • supported by master • only IRT switches are used • enough bandwidth available IRT channel Standard channel Cycle 1 IRT channel Standard channel IRT channel Cycle 2 = time window Cycle 1 e.g. 2 ms position control loop Powerlink isochronous communication Modbus/TCP RT communication Standard communication EtherCAT Summary © EtherCAT Technology Group Industrial Ethernet Technologies In principle both varieties (RT+IRT) can be mixed. Since IRT switches have to be used then, one can say: RT devices can be integrated in IRT networks, if there is sufficient bandwidth and if the master supports this. Siemens recommends in the current System Manual* to position the RT devices at the end of the Profinet system, outside of the IRT sync domain. Synchronization between the RT and IRT devices is not possible (“if you want to synchronize with IRT, the respective Profinet devices must support IRT communication”). * Source: Siemens Profinet System Description, page 153, “Setting up Profinet with IRT”, 07/2010, A5E00298288-05 Industrial Ethernet Technologies Page 14 © EtherCAT Technology Group, August 2011 PROFINET IRT System Planning (I) Classification Profinet Ethernet/IP CC-Link IE Sercos III Powerlink Modbus/TCP EtherCAT Input for planning/configuration of the network: • the topology of the network • For every connected port of every device in the IRT network the partner port has to be configured – configuring the cable length or signal delay time is also recommended for better results • and for every transmission the optimization algorithm needs: • the source- and the target node, • the amount of transmission data, • projected features of the connection path (e.g. Redundancy) Output of the projection for every transmission and device respective switch: • Ports and exact transfer time timing for each frame Summary © EtherCAT Technology Group Besides hardware costs, the crucial issue of Profinet IRT is the complex system planning. Industrial Ethernet Technologies Page 15 © EtherCAT Technology Group, August 2011 PROFINET IRT System Planning (II) Classification Profinet Ethernet/IP CC-Link IE • Complex recursive optimization problem • Configuration and System Planning is a process executed by a central Algorithm in the Engineering System. • Small change in input (e.g. one more node) may lead to big change in output (cycle time and thus performance), due to unpredictable behavior of optimization algorithm Sercos III Powerlink Modbus/TCP Strong interdependency between topology and performance EtherCAT Summary © EtherCAT Technology Group For each node all communication relationships have to be known and scheduled. Of course there are strong interdependencies between the schedules. Therefore the system planning is a complex recursive optimization problem without a straightforward solution – even with fairly simple topologies. Due to the complex nature of this problem the optimization algorithm may come up and be satisfied with a relative rather than the absolute optimum – which means, that a small change in the configuration (e.g. adding just one more node) may result in large changes in the network performance. The algorithm was developed by Prof. Dr. Ulrich Lauther and has 23.000 lines of code, according to Siemens. A license for the planning algorithm (in dll format) can meanwhile be obtained by PI members – it remains a black box algorithm, however. Industrial Ethernet Technologies Page 16 © EtherCAT Technology Group, August 2011 PROFINET IRT Performance Classification Published… Profinet Ethernet/IP CC-Link IE Sercos III Powerlink but… Modbus/TCP EtherCAT Valid for a network CLUSTER (4 networks) only, not for a single network… Summary Pictures sourced from PI website © EtherCAT Technology Group For several years, this was the performance data table published for Profinet IRT. However, the table is valid only for a cluster of networks: 150 nodes sharing 50% bandwidth at 1ms cycle time means 500 µs / 150 = 3,33 µs per node. The shortest Ethernet frame takes 7µs to transmit. This is not to state that Profinet IRT was not fast enough for most applications... Industrial Ethernet Technologies Page 17 © EtherCAT Technology Group, August 2011 IRT Topology – and some conclusions Classification Profinet Ethernet/IP CC-Link IE Sercos III Powerlink Modbus/TCP EtherCAT • Line, Branch, Tree Topology is supported • Cascading of switches in a line has limit of 20 - 25 devices • → this means: branch/star topology is the common design, whether desired or not • For any installation with more than 20 - 25 devices, network branches are required • The network topology layout requires a top-down approach • The planning process will mandate the layout and wiring of a configuration • performance data is true for a specific topology ONLY • Topology restrictions apply when designing a network with a required performance Summary Pictures sourced from PI website © EtherCAT Technology Group The non-linear and even unpredictable interdependency between topology and performance may require several iterations (or „try and error“ steps) when designing a network layout for a required performance. Industrial Ethernet Technologies Page 18 © EtherCAT Technology Group, August 2011 Profinet IRT, RT, IO + RT Classes B Classification Profinet Ethernet/IP Software based Profinet (Profinet RT) Sercos III Powerlink Soft Real Time Modbus/TCP Hardware assisted Profinet (Profinet IRT) RT Class 1 Best effort approach based on standard network components: CC-Link IE C RT Class 2 RT Class 3 time slicing without topology planning: Soft Real Time with Hardware Support PLC Type Applications with topology oriented network planning + defined timing for each connection path: Hard Real Time Motion Applications All variants are called EtherCAT Profinet IO Summary © EtherCAT Technology Group In order to avoid the complex topology network planning process, an intermediate approach had been introduced: RT Class 2 (within Siemens also called IRT “Flex” or “IRT with high flexibility”) using Profinet chips (e.g. ERTEC). High priority network traffic is sent in the IRT time slice, but without predefined timing for each connection. Low priority communication is handled in the NRT time slice. Profinet chips have to be used throughout. Cyclic behavior can be achieved if the network load is low and the application tasks are synchronized with the communication cycle. The downside is that there is unused bandwidth that is exclusively reserved and cannot be used for other communication. IRT Flex was intended as a simplified Profinet IRT variety for PLC type applications that utilize ERTEC profinet chips (Siemens Simatic S7). However, due to incompatibility issues, IRT Flex is not promoted or recommended by Siemens any more. RT Class 3 (also called IRT “TOP” or “IRT with high performance”) is the variant formerly referred to as Profinet IRT. This approach provides hard real time behavior but requires the detailed network planning (topology editor) and the optimization algorithm: the topological information from the configuration is used for planning the communication. Siemens is adopting this variant for PLCs as well. PTO/PNO generally downplays the differences between the Profinet variants, summarizing all of them with the term “Profinet IO”. Industrial Ethernet Technologies Page 19 © EtherCAT Technology Group, August 2011 Profinet Conformance Classes Classification B Software based Profinet (Profinet RT) Profinet Ethernet/IP CC-Link IE RT Class 1 Best effort approach based on standard network components: Soft Real Time C Hardware assisted Profinet (Profinet IRT) RT Class 2 time slicing without topology planning: RT Class 3 with topology oriented network planning + defined timing for Soft Real Time with each connection path: Hardware Support Hard Real Time Sercos III Conformance Class A Conformance Class B Conformance Class C Powerlink with Topology Recognition with LLDP (no SNMP) MRP optional with Topology Recognition (SNMP, LLDP-MIB) MRRT optional with Topology Recognition (SNMP, LLDP-MIB) CutThrough Switch Behavior Mandatory 4 Priorities Mandatory MRPD mandatory Modbus/TCP EtherCAT PLC Type Applications All variants are called Profinet Summary Motion Applications IO © EtherCAT Technology Group In addition to the RT classes, Profinet has introduced (see IEC 61784-2) Application Classes (Isochronous for motion control, Non-isochronous for factory process + building automation), Redundancy Classes (MRP: Media redundancy protocol; MRRT: Media redundancy for real-time (dropped in Profinet V2.3); MRPD: media redundancy for planned duplication) and Conformance Classes. The Conformance Classes predominantly define the support for the topology recognition features. Redundancy Classes and Conformance Classes are interlinked. Topology Recognition originally was required for Conformance Class B + C, only; meanwhile this is required for Conformance Class A (but without LLDP-MIB). It was found that there are issues when using unmanaged switches with Profinet Class A (in B managed switches are mandatory): common COTS switch chips forward LLDP (Link Layer Discovery Protocol) frames to all ports, which leads to substantial additional network traffic (the frames are handled like broadcast frames). Conclusion: even for Conformance Class A Profinet networks, in reality managed switches have to be used (for LLDP) - and they have to be selected very carefully (IT support required). see also EFTA 2007 Conference Paper by Iwan Schafer + Max Felser, Berne University of Applied Sciences: “Topology Discovery in PROFINET”: http://www.felser.ch/download/ETFA-01-2007.pdf Industrial Ethernet Technologies Page 20 © EtherCAT Technology Group, August 2011 Profinet Robustness (I) Classification Profinet Ethernet/IP CC-Link IE Sercos III • Profinet can be vulnerable if certain non-Profinet network traffic occurs, such as high density of (short) ARP requests • This applies to RT as well as to IRT, since in IRT the NRT channel is used for supporting services, such as: • Synchronization (IEEE1588) • All acyclic services (which are used by some masters in a cyclic way). • Discovery protocol (LLDP) Short Frames Bus Powerlink Modbus/TCP EtherCAT Summary Isochronous Real-Time CPU Non Real-Time Synchro nization IRT CPU busy • Therefore Profibus International has published a spec/guideline called „PROFINET IO Net load“ • Thus the Profinet user is now responsible to ensure that certain network load limits are not exceeded. © EtherCAT Technology Group Profinet marketing has always claimed that Profinet provides (quote from PI “Profinet Benefits” presentation): • “Unlimited IT communications parallel to real-time communications • Easy use and integration of standard Ethernet applications” However, since the Profinet technology itself (unlike e.g. EtherCAT) has no means to control or restrict incoming “unlimited IT communications”, there can be rare overload situations that cause the network to fail. If the communication processor of a drive is too busy to handle e.g. an occasional burst of broadcasted ARP frames and therefore cannot keep up with executing the IEEE1588 services, the synchronization fails (of this drive, and all nodes further downstream) and the master will consider these nodes to have an error – the system stops. One could consider this an implementation problem that can be avoided by providing sufficient processing resources throughout – but it is a problem that occurs in reality, especially in large networks. It can be challenging to ensure that certain network load limits are not exceeded. If e.g. a service notebook starts to scan the network for IP addresses at high pace, who knows what kind of load condition this generates? By the way: Industrial Ethernet technologies that tunnel other Ethernet traffic - such as EtherCAT – remain in control of the additional network load and avoid such situations by design. Industrial Ethernet Technologies Page 21 © EtherCAT Technology Group, August 2011 Profinet Robustness (II) Classification Profinet Ethernet/IP CC-Link IE Sercos III Powerlink Modbus/TCP EtherCAT Summary Screenshot from Profibus International website : http://www.profibus.com/nc/downloads/downloads/profinet-io-net-load-1/display/ © EtherCAT Technology Group There are reports suggesting that exceeding 5% ARP load for 1 ms can already be an issue. Industrial Ethernet Technologies Page 22 © EtherCAT Technology Group, August 2011 Profinet / EtherCAT Comparison by Profibus International (PI) Classification Profinet Ethernet/IP CC-Link IE Sercos III Powerlink Modbus/TCP EtherCAT • On press conferences in Nov 2007, PNO/PI published performance comparsions with EtherCAT • It was found that in typical application scenarios (line structure, 50 nodes, < 60Bytes cyclic data per node) EtherCAT is substantially faster than Profinet IRT • According to the PNO, Profinet IRT is faster if the average payload per node exceeds 60 Bytes • However, some features of EtherCAT (such as full-duplex frame usage and pipelining of frames) were not considered Summary Picture sourced from PNO press kit © EtherCAT Technology Group Within the research project “ESANA”, funded by the German Federal Ministry of Education and Research, Siemens, Phoenix Contact and some other parties were looking for performance enhancement possibilities for Profinet. This is remarkable, since it documents that in PNO/Siemens/Phoenix view the current Profinet IRT is not fast enough to succeed. The performance comparison shown on this slide is at least questionable: even with very favorable assumptions for Profinet it was not possible to reproduce the results. EtherCAT is substantially faster than shown, since several EtherCAT features were not taken into account: - EtherCAT can use the same bandwidth for input and output data (full-duplex usage of the frame). - EtherCAT can send the next frame before the first one has returned (pipelining of frames). One of the authors of the study has meanwhile admitted this shortfall. So in fact EtherCAT is faster than Profinet IRT, regardless of the payload per node. Furthermore, all the Profinet calculations do not include the local stack performance in the slave devices. Unlike with EtherCAT, in a Profinet IRT slave device a communication µC (ERTEC: ARM) is taking the data from the MAC interface and makes it available to the application. With EtherCAT, this is done on the fly in hardware, the data is made available in the DPRAM or Input/Output of the EtherCAT Slave Controller without further delay. Industrial Ethernet Technologies Page 23 © EtherCAT Technology Group, August 2011 Profinet / EtherCAT Comparison by Profibus International (PI) Classification • When taking all EtherCAT Features into account, the performance comparison looks different: Profinet Ethernet/IP CC-Link IE Sercos III Powerlink Modbus/TCP EtherCAT • EtherCAT is faster, regardless of the payload per node Summary © EtherCAT Technology Group This slide shows the relative performance comparison if all the EtherCAT Features are taken into account (purple line). This calculation was confirmed by a conference paper of Dr. Gunnar Prytz, ABB Research Center, at ETFA 2008 („A performance analysis of EtherCAT and Profinet IRT“), which can be downloaded from the ETG website: http://www.ethercat.org/pdf/english/ETFA_2008_EtherCAT_vs_PROFINET_IRT.pdf The blue line shows the comparison according to the PNO paper. ETG was asked to provide a statement regarding the PNO press conference. Here it is: •We are pleased that the PNO has chosen EtherCAT as performance benchmark and thank for the associated publicity. •The PNO acknowledges our statement, that high-end performance with cycle times significantly below 1 ms is a relevant selection criteria for an Industrial Ethernet solution. •The PNO analysis shows clearly, that in typical application scenarios EtherCAT is much faster than the fastest Profinet variant IRT class 3. •We congratulate the PNO on having found a special scenario (comb structure, in which the nodes in the branch lines are not updated in each cycle), in which a future version of Profinet IRT seemingly matches or exceeds EtherCATs performance. •This comb structure was compared with an EtherCAT line structure – and not with an EtherCAT comb structure, in which the nodes in the branch lines can be updated in each cycle. •EtherCAT is and remains the fastest Industrial Ethernet solution. •EtherCAT does not need and will not need the complex network planing and optimization that current and future Profinet IRT variants require. Industrial Ethernet Technologies Page 24 © EtherCAT Technology Group, August 2011 Next Generation Profinet IRT Classification Profinet Ethernet/IP CC-Link IE Sercos III Powerlink Modbus/TCP • In November 2007 also a new Profinet IRT Version was announced: originally named IRT+, this version can be considered Profinet V4 • In the new version intends to improve the performance in line topologies by – Shortening the frames as they pass through subsequent nodes (Dynamic Frame Packing DFP), which requires new datagram structure with multiple CRCs – Changed interpretation of the Ethernet MAC address (Destination address contains Frame ID) to reduce forwarding time in IRT ASICs (“Fast Forwarding“) • This new Version requires new Profinet ASICs • In Oct 07 the price for the old ASICs was reduced by 40% EtherCAT Summary © EtherCAT Technology Group Profibus organization PNO showed a Profinet V4 demonstrator in April 2008 at Hannover Fair. According to a PNO press release of Nov 26, 2008, “The specifications will be finished in the second half of 2009“. Similar to RT and IRT version that are summarized as “Profinet IO” in order to play down the many varieties of the technology, the Profinet organization does not use the term IRT+ (or Profinet V4) any more. The features of the new version which requires new chips are contained in the Profinet specification V2.3, which was published in October 2010. Since EtherCAT achieves a better bandwidth utilization (less overhead per node), it will remain the fastest Industrial Ethernet technology, even though there may be scenarios with just a few nodes where a carefully optimized network consisting of Profinet V4 nodes may come close to the performance of an EtherCAT with default settings. Industrial Ethernet Technologies Page 25 © EtherCAT Technology Group, August 2011 IRT+: Dynamic Frame Packing (DFP) Classification DFP aims to enhances Profinet IRT Performance in Line Topologies – Frame Efficiency will be improved by shortening frames dynamically in node (only in line topology) – In DFP-Lines, IP-Frames (other Ethernet Traffic) will be fragmented – just as with EtherCAT Profinet Ethernet/IP CC-Link IE Sercos III Powerlink Modbus/TCP EtherCAT Summary Picture: Phoenix Contact @ SPS/IPC/Drives Congress 2009 © EtherCAT Technology Group DFP will work in line topologies, only. With DFP Profinet introduces the layer 2 fragmentation of IP-Frames – another feature that EtherCAT has introduced and which Profinet marketing used to condemn… Industrial Ethernet Technologies Page 26 © EtherCAT Technology Group, August 2011 IRT+: Fast Forwarding (FF) Classification Profinet Ethernet/IP CC-Link IE Sercos III Powerlink Modbus/TCP • Fast Forwarding (FF) will reduce Cut-Through Forwarding Time by introducing Multicast MAC Adresses with integrated Profinet Address – Cut Through Switch can decide („forward to which port?“) after reception of Profinet destination address (FID, frame ID) DA Header SA VLAN ET FID Datagram FCS Datagram FCS Decision Time without FF FID DA Header SA VLAN ET FID Decision Time with FF EtherCAT Summary © EtherCAT Technology Group For introducing Fast Forwarding the address usage had to be modified. The goal is to reduce the „per-node-delay“ of Profinet. Since Profinet Version 2.3 the FrameID is part of the OUI (Organizationally Unique Identifier) in the MAC address, with the first two bits set to “1” (= Locally Administered Group Address). Industrial Ethernet Technologies Page 27 © EtherCAT Technology Group, August 2011 Profinet V2.3 – and IRT+ Timeline Classification Profinet • Next Generation Profinet (IRT+) was announced in 2007 • End of 2010, Profinet IRT V 2.3 Specification was released • V2.3 contains the IRT+ Features DFP + FF, plus more changes such as Ethernet/IP CC-Link IE Sercos III Powerlink Modbus/TCP • • Fragmentation of NRT Frames (Profinet now also makes use of Tunneling) • Configuration in Run Mode • Network Scan and Parameter Upload • Media Redundancy added • Boot-Up for IRT (Class 3) modified However, Devices supporting Dynamic Frame Packing and Fast Forwarding (IRT+) are not expected before 2013 EtherCAT Summary © EtherCAT Technology Group As of August 2011, the conformance test cases for IRT+ are scheduled for mid of 2013. So far there is not even Profinet Master ASIC officially announced that will support DFP and FF – it is understood, though, that Siemens is working on a next generation ERTEC chips, which will most likely support these features. These nextGen ERTECs are not expected before 2013 either, so the Profinet community will have to wait some more years for IRT+. Industrial Ethernet Technologies Page 28 © EtherCAT Technology Group, August 2011 New Profinet Chip TPS1 “Tiger” Classification Profinet Ethernet/IP • Developed by Phoenix Contact (+ inIT), distributed by Renesas, marketed by KW Software • Goal: Simpler to integrate than Siemens ERTEC200 • DFP - Dynamic Frame Packing + FF - Fast Forwarding not (yet) supported • PHYs + Protocol CPU integrated, but no Application µC • Aimed at I/O and Drives • Initially announced for 2009, first samples mid of 2011, series production expected for Q1/2012 • Marketing: “Joint Development of Phoenix and Siemens” in order to stress compatibility with ERTEC CC-Link IE Sercos III Powerlink Modbus/TCP EtherCAT Summary Picture sourced from KW Software Website © EtherCAT Technology Group TPS1 is also called “Tiger” chip, since it was planned to be released in the Year of the Tiger (2/2010 – 2/2011). Even though it will now be released in the Year of the Rabbit (or Hare), no plans are known to officially rename it the “Rabbit” chip. The Tiger aka TPS1 (aka Rabbit) chip is a Phoenix Contact development (subcontracted to the Institut Industrial IT (inIT) of the University of Applied Science Westfalen Lippe) – and Phoenix Contact (not Siemens) also was the driving force behind Profinet V4 (IRT+). So the TPS1 was intended to be the first chip supporting the new Profinet version. But end of 2009 it looked that Siemens was unhappy about Phoenix trying to take the lead in Profinet advancement and therefore forced Phoenix into a lengthy consensus building process within PNO in order to delay the availability of Profinet V4. Meanwhile Siemens seems to have recognized that this strategy backfired on Profinet in general. So in March 2010 PNO held a press conference where in total contrast to the statements of Nov 2009, where Siemens had denied any involvement in the TPS1 development, Siemens and Phoenix Contact called the TPS1 a joint development of both companies which they plan to use also in the future in devices of their own product portfolio. Nevertheless, PNO committees changed the Fast Forwarding technology again in fall 2010 and thus too late for the first version of the TPS1 chip. So the TPS1 chip will initially not support the DFP and FF – which is not such a big problem, since there is no master in sight supporting these features anyhow. As mentioned before, Siemens is believed to be also working on a next generation Profinet chip, which is not expected before 2013 – and it seems that Phoenix accepts that this chip will be the first one to support DFP and FF. The TPS1 is for slave devices only. The integrated “Profinet CPU” is an ARM core and executes the time critical parts of the Profinet protocol. Digital I/O can be connected directly to the chip. For communication with the application (host) CPU the chip contains internal DPRAM, which can be accessed via serial or parallel interface. Since its cyclic process data image is limited to 340 bytes, it is hardly suitable for bus couplers of modular I/O devices or other more complex devices. KW Software claims that with this chip the interface hw costs can be reduced to 13€ (~19$). Industrial Ethernet Technologies Page 29 © EtherCAT Technology Group, August 2011 PROFINET ASIC Pricing Siemens/NEC ERTEC 200 ERTEC 400 Functionality PROFInet RT + IRT IEEE 1588 ARM 9 Processor 2 Port Switch with PHY PROFInet RT + IRT IEEE 1588 ARM 9 Processor 4 Port Switch, no PHY PCI Interface RMII Interface (4port) CC-Link IE Application field Single drives Comparable field devices High-end Motion Controller Network components Sercos III ASIC Technology 0.15 µm Technology 304pin BGA 19 x 19 mm 0.15 µm Technology 304pin BGA 19 x 19 mm Powerlink Pricing (since Oct 2007) 12.57 € @ order size 350 units 30.00 € @ order size 350 units Classification Profinet Ethernet/IP Modbus/TCP EtherCAT Pricing shows that PROFInet is more on the „complex“ field device network side than on the cost efficient I/O system side. Summary © EtherCAT Technology Group Industrial Ethernet Technologies First samples of the ERTEC 400 were shipped in May 2005, first samples of the ERTEC 200 were shipped in May 2006. Initially, the ERTEC 400 was sold for 38€ and the ERTEC 200 for 19 € per chip (@ 10.000 units/year). As of Oct 1st, 2007, Siemens lowered the prices substantially, presumably since the next generation IRT which requires new ASICs is under development. 12.57€ respective 30€ per chip still exceeds fieldbus cost levels not only for simple devices, in particular if one considered the amount of memory needed: A Profinet slave device needs about 1 MByte of Code for the communication part. For implementation with ERTEC chips, a VxWorks license is required: the stack is provided as object code for this RTOS. Industrial Ethernet Technologies Page 30 © EtherCAT Technology Group, August 2011 PROFINET and INTERBUS Classification Profinet the Interbus View… Management Level Ethernet/IP CC-Link IE Sercos III Powerlink Modbus/TCP Control Level Ethernet TCP/IP Complex field devices Simple field devices EtherCAT …there is life below PROFINET… Summary Picture sourced from Interbus Club website © EtherCAT Technology Group Due to system complexity and costs Interbus as well as Profibus expect life below Profinet. Industrial Ethernet Technologies Page 31 © EtherCAT Technology Group, August 2011 IRT and Siemens Motion Control Classification For closed loop motion control Siemens is using Drive-CLiQ, not Profinet IRT… Profinet Drive-CLiQ: Siemens Motion Control Network based on 100 Mbit Ethernet Ethernet/IP CC-Link IE Sercos III Powerlink Modbus/TCP EtherCAT Summary Pictures sourced from Siemens website © EtherCAT Technology Group Interesting enough, Siemens has also developed another Ethernet based motion control network: Drive-CLiQ. Drive-CLiQ is used to connect the Sinamics motion controller containing the path planning algorithm (trajectory controller) with the drives, the position sensors (encoders, tachometers, resolver) and also with terminal modules (HMI). Profinet IRT and Profibus are used to network and synchronize several such motion controllers – so primarily for controller/controller communication. End of November 2010 Siemens announced that they are is now even opening Drive-CLiQ to feedback sensor manufacturers who are invited to implement this interface in their encoders, resolvers, tachometers and linear position sensors. Siemens also provides a special chip for that purpose. Industrial Ethernet Technologies Page 32 © EtherCAT Technology Group, August 2011 PROFINET Adoption Rate Classification Profinet Ethernet/IP CC-Link IE Sercos III Powerlink Modbus/TCP EtherCAT • As of July 2011, Profibus International claimed that the online product guide meanwhile contains 500 Profinet devices. • However, as of August 15, 2011, there were 428 entries, out of which 170 are cables and connectors, 41 are services and tools, 46 are interface boards, chips and switches, and 25 are fieldbus-independent I/O terminals – and 70% of the remaining devices are Siemens… • Also, the product guide lists only 3 Profinet drive vendors besides Siemens – and none of them supports IRT (RT Class 3) Summary © EtherCAT Technology Group Given that the first version of Profinet was introduced 10 years ago, and that it is promoted by the market leading automation giant, the adoption rate of Profinet is poor. As of August 2011, there are very few non-Siemens Profinet masters – in particular non-Siemens IRT-masters are difficult to find. Also, there are no known non-Siemens IRT drives. Industrial Ethernet Technologies Page 33 © EtherCAT Technology Group, August 2011 PROFINET Summary Classification • 3 different Versions: Proxy Approach, Soft Real Time, Isochronous Real Time Profinet • Proxy Approach: vaporware Ethernet/IP • RT: rather complex Profibus replacement, but will have market share due to support by Siemens CC-Link IE • There will be underlying networks (for cost reasons) Sercos III • IRT for motion control: meets motion control requirements but very complex and expensive Powerlink • IRT expected to be predominantly Siemens only (like Profibus DPV2 for Motion Control) Modbus/TCP EtherCAT Summary © EtherCAT Technology Group Profinet RT is not low cost, requires a lot of code and is not high performance, but in the long run it will be a success – regardless of the technology, simply due to the Siemens (+ PNO/PTO) market position, just like Profibus. The German car makers have announced to use Profinet in car assembly lines „if it provides technological and economical advantages“ (quote). Daimler, e.g., has clearly stated that this announcement does not cover the power train business, where CNC and other motion control applications are in place. Furthermore, there will be underlying fieldbus systems in the car assembly line, too. But certainly the auto makers announcement gave Profinet (RT) a marketing push. The situation is different for Profinet IRT: A solution with sufficient performance, but with rather expensive chips and a very complex network planning and configuration tool where the key algorithms are not open. IRT is positioned at servo motion control applications and will therefore be – just like Profibus MC – a Siemens motion control solution with limited support from third party vendors (just like Profinet MC). Plus, Siemens latest Motion Control product line prefers a different communication link for closed loop control: DriveCliq, which uses Ethernet physical layer, only. Industrial Ethernet Technologies Page 34 © EtherCAT Technology Group, August 2011 Ethernet/IP: Overview Classification Profinet Ethernet/IP • ODVA (Rockwell) Approach: „IP“ stands for Industrial Protocol • CIP (Common Industrial Protocol): common object library for Ethernet/IP, ControlNet, DeviceNet, CompoNet • Follows Approach A. Device Profiles CIP Motion Valves CIP CIP Message Routing, Connection Management Transport EtherCAT Other CIP Data Management Services Explicit Messages, I/O Messages Application Powerlink Modbus/TCP Robots CIP Application Layer Application Object Library CC-Link IE Sercos III I/O A Encapsulation TCP UDP ControlNet Transport DeviceNet Transport CompoNet Transport Network IP Data Link EtherNet CSMA/CD ControlNet CTDMA CAN CSMA/NBA CompoNet Time Slot Physical EtherNet Physical Layer ControlNet Phys. Layer DeviceNet Phys. Layer CompoNet Phys. Layer Summary © EtherCAT Technology Group Ethernet/IP claims to use the same application layer as Devicenet, Controlnet and CompoNet. This may be beneficial for those that are familiar with those fieldbus networks. However, taken from the experience when implementing Devicenet and Controlnet, the synergy effects are expected to be somehow limited, since the communication technologies and even the protocols differ substantially. Industrial Ethernet Technologies Page 35 © EtherCAT Technology Group, August 2011 Ethernet/IP Functional Principle Classification Profinet Consumer / Producer Model • Advantage: very efficient for slave-to-slave Communication • Disadvantage: requires Broadcast communication and thus filtering in each device Ethernet/IP CC-Link IE producer consumer consumer accept consumer accept Sercos III prepare filter filter filter send receive receive receive Powerlink Modbus/TCP broadcast communication EtherCAT Summary © EtherCAT Technology Group By applying broadcast or multicast communication, the switches cannot forward incoming frames to a single destination port only - so they act like (full-duplex) Hubs, but with larger delay. Industrial Ethernet Technologies Page 36 © EtherCAT Technology Group, August 2011 Ethernet/IP Switch + Router Issues Classification Profinet Ethernet/IP CC-Link IE Sercos III Powerlink Modbus/TCP EtherCAT from a technical paper found on the ODVA website Summary http://www.odva.org/Portals/0/Library/Publications_NotNumbered/Utilization_of_Modern_Switching_Technology_in_EtherNetIP_Networks.pdf © EtherCAT Technology Group This paper by Anatoly Moldovansky, a senior engineer from Rockwell Automation (and a nice guy!), highlights some of the issues with Ethernet/IP: there is a need for routers with multicast/broadcast control features, and there is no standard way to implement or configure these. IGMP snooping constrains the flooding of multicast traffic by dynamically configuring switch ports so that multicast traffic is forwarded only to ports associated with a particular IP multicast group. Furthermore, high-end switches typically have high-end prices. Rockwells documentation states that switches for Ethernet/IP have to support IGMP snooping as well as port mirroring (for troubleshooting). They should also support VLAN and SNMP – so manageable switches are required. Industrial Ethernet Technologies Page 37 © EtherCAT Technology Group, August 2011 Ethernet/IP Topology Classification Profinet Ethernet/IP CC-Link IE • Standard Switched Ethernet Topology • By nature: unpredictable Switch + Stack Delays • Network separation by Router with IGMP snooping • Limited Real Time Capabilities Router Sercos III Powerlink Modbus/TCP EtherCAT Summary © EtherCAT Technology Group Even though the switch delays are unpredictable by nature, the delays introduced by the software stacks are much more significant. Industrial Ethernet Technologies Page 38 © EtherCAT Technology Group, August 2011 Ethernet/IP Device Level Ring (DLR) Classification Profinet Ethernet/IP CC-Link IE • Cable Redundancy Technology based on Ring topology • Dedicated Ring Supervisor Node and DLR protocol for network management • Devices with special embedded switches • Introduced in 2008, first DLR products in 2009 • DLR unaware nodes should be connected through 3-port protocol aware switches Sercos III Powerlink Modbus/TCP EtherCAT Summary Picture: Rockwell Automation Press Release, Oct. 2009 © EtherCAT Technology Group DLR technology first published in Nov 2008 version of Ethernet/IP spec. First products in Q3 2009. Requires special nodes who support the DLR protocols Ring supervisor node monitors network status with “Beacon frames”, per default every 400µs. In case of failure, ring supervisor actively reconfigures the network (e.g. by remotely opening or closing ports) ODVA recommends to connect “DLR unaware nodes” through 3-port protocol aware switches. Fault recovery time for a 50-node network: about 3 ms. Enhances the Ethernet/IP topology options, also supports combinations of several rings and combinations of redundant rings with classical Ethernet star topologies – at the price of special nodes. Industrial Ethernet Technologies Page 39 © EtherCAT Technology Group, August 2011 Ethernet/IP Performance Classification Profinet • Minimum Cycle Time (RPI; Requested Packet Interval) is dependent on number of CIP connections • Each Device can have multiple CIP Connections min_RPI = (number of connections x 2) / (no. of frames/second)* * (assumed all connections request same “RPI” scan time). Ethernet/IP CC-Link IE No. of Min_RPI (ms) Connections with 5000 Frames/sec Min_RPI (ms) with 10000 Frames/sec Min_RPI (ms) with 25000 Frames/sec (standard scanners) (high performance scanners) (ultra high performance scanners) 4 1,6 0,8 0,32 8 3,2 1,6 0,64 16 6,4 3,2 1,28 32 12,8 6,4 2,56 64 25,6 12,8 5,12 Sercos III Powerlink Modbus/TCP EtherCAT Summary These theoretical cycle times do not take switch and remote stack delays into account; Rockwell quantifies the switch delay at 0,1 ms per switch. © EtherCAT Technology Group Industrial Ethernet Technologies Ethernet/IP distinguishes CIP and TCP Connections. A CIP connection transfers data from an application running on one end-node to an application running on another end-node. A CIP connection is established over a TCP connection. A single TCP connection can support multiple CIP connections. Most Rockwell Ethernet/IP devices support up to 64 TCP connections, the number of CIP connections differs from device to device (e.g. 1756-ENBT: 128 CIP connections, 1756-EN2T and later: 256 CIP connections). All Rockwell scanners support a maximum of 32 multicast tags (producer/consumer I/O connections). For communication with an I/O device, typically more than one CIP connection is used (e.g. one for implicit messaging, one for explicit messaging). The Rockwell Automation (RA) publication “Ethernet Design Considerations” (ENET-RM002A-EN-P, July 2011) shows the complex process of how to predict the network performance. There is also an “EtherNet/IP Capacity Tool“ available. Rockwell also recommends to add scanner cards to the controller and divide the scanning function between the cards if the throughput is not sufficient. The Packet Rate Capacity (packets/second) of most Rockwell Ethernet/IP scanners is 5000 Frames/sec – with the exception of the ControlLogix series, where Rockwell is constantly increasing the scanner card performance. As of August 2011, the latest generation (firmware >3.6) scanners support up to 25.000 frames/second (see Table 9 of Rockwell Automation Publication ENET-RM002A-EN-P, July 2011). With these new high end scanners (1756-EN2xx, 1756-EN3xx) the right hand column of the cycle time table applies – and it is obvious that the system real time performance remains comparatively poor. The standard ControlLogix Ethernet IP Bridge (1756-ENBT) still supports 5000 Frames/sec. The release notes (Publication 1756-RN591Q-EN-P - January 2008) of this device contain the following passage: Performance Considerations: In general, the 1756-ENBT module is capable of supporting 5,000 packets/seconds. However, it is possible in some applications, depending on the combination of connection count, RPI settings, and communication formats, that the product may be able to achieve only 4,000 packets/seconds. See also: Rockwell Automation (RA) publication “Ethernet/IP Performance” (ENET-AP001D-EN-P, released October 2004, according to RA website still valid in Aug 2011) Industrial Ethernet Technologies Page 40 © EtherCAT Technology Group, August 2011 Ethernet/IP + CIP Sync Classification Profinet Ethernet/IP CC-Link IE Sercos III • Ethernet/IP has limited Real Time Capabilities: – limited Cycle Time Performance, limited Determinism – acceptable Throughput (for large Data Units) • CIP Sync adds Time Synchronization, but does not reduce cycle time or process data performance • Distributed Clock Protocol: IEEE 1588 • CIP Sync: announced April 2003, added to CIP spec in May 2006 (Version 3.0). First products shipping since 2009. Powerlink Modbus/TCP EtherCAT Summary © EtherCAT Technology Group CIP sync was introduced to improve the real time behavior of the system. The marketing message given by ODVA tries to tell that by adding synchronization the real time capability is achieved – but time synchronization does not improve cycle time, throughout or performance. CIP sync was announced in April 2003, and included in Version 3.0 of the CIP spec in May 2006. First CIP sync products from Rockwell Automation are the sequence of events (SOE) data capture modules that support timestamps. The version with CIP sync support is shipping since mid of 2009. Industrial Ethernet Technologies Page 41 © EtherCAT Technology Group, August 2011 What is IEEE 1588? Classification Profinet Ethernet/IP • A method for precision time synchronisation tailored to requirements of distributed measurement and control systems. Widely independent of transport protocol. • 1588 on Ethernet: Version 1 (2002) based on UDP/IP, Version 2 (2008) also with direct Ethernet (Layer2) option CC-Link IE Sercos III Powerlink Modbus/TCP EtherCAT Summary Source: introduction_to_1588.pdf by IEEE © EtherCAT Technology Group IEEE 1588, officially entitled "Standard for a Precision Clock Synchronization Protocol for Networked Measurement and Control Systems" , is a technology for time synchronization that is or will be used by a variety of systems: Ethernet/IP, Profinet, Powerlink,... EtherCAT also supports gateways to IEEE 1588 systems for external time synchronization. The first version of IEEE1588 was published in November 2002. Version 2 (IEEE 1588-2008) followed in March 2008 and added various features, including the layer 2 transport option (embedded in the Ethernet frame without UPD/IP) and the “transparent clock” approach which improves the accuracy for linear systems (line topology) since it eliminates cascaded clocks. V2 of the standard is not directly interoperable with V1. IEEE supports an annual international symposium on 1588 technology. In conjunction with this symposium a plug fests for improving interoperability is held. Industrial Ethernet Technologies Page 42 © EtherCAT Technology Group, August 2011 IEEE 1588 Hardware Support Classification Profinet • In order to achieve good results hardware timestamping is required • This functionality can be implemented in MACs, PHYs or integrated solutions. Ethernet/IP CC-Link IE Sercos III Powerlink Modbus/TCP EtherCAT Summary Source: Dirk Mohl, www.ieee1588.com © EtherCAT Technology Group In general the stack processing times limit the accuracy in case of pure software implementations. For good results hardware with built in IEEE1588 timestamp support has to be used – and the corresponding switches. First silicon was introduced by Intel and Hyperstone, meanwhile National Semiconductor, Freescale, Zarlink and others provide processors, MACs and PHYs with such features. FPGA-IP with IEEE1588 timestamp functionality is also available. Industrial Ethernet Technologies Page 43 © EtherCAT Technology Group, August 2011 CIP Sync in ISO/OSI Model Classification Profinet Ethernet/IP Layer 5...7 Layer 4 CIP Synchronized Clock Value TCP 1588Extension UDP (User Datagram Protocol) CC-Link IE Sercos III Layer 3 „explicit Messages“ Powerlink Modbus/TCP Layer 1 and 2 EtherCAT IP „Real-TimeI/O-Data“ n oC OTS H (Internet Protocol) W any m o re optional Hardware Support for better Accuracy Ethernet according to IEEE 802.3 C A ? CIP...Common Industrial Protocol Summary © EtherCAT Technology Group In order to make the time synchronization independent from software jitters and stack performance, at least the time stamp functionality had to be implemented in hardware (directly in or at the Ethernet MAC). This turns the class A approach “Ethernet/IP” into the class C approach “Ethernet/IP with CIP Sync”, even though silicon with direct timestamp support may be considered COTS technology at some stage. Industrial Ethernet Technologies Page 44 © EtherCAT Technology Group, August 2011 Ethernet/IP + CIP Sync I/O Drive I/O Controller I/O Drive I/O Drive Controller Drive Powerlink I/O Controller Sercos III Drive CC-Link IE Limited No. of Connections Bus cycle time is typically 5 .. 10 ms Reaction time is typically 15 .. 30 ms Determinism is added via system-time-synchronized actions and timely non-deterministic communication. Drive Ethernet/IP • • • • I/O Profinet Best suited and typically used as Controller to Controller network Drive Classification Modbus/TCP EtherCAT Summary Example Ethernet/IP Network © EtherCAT Technology Group Even though it is more and more used for I/O communication as well, the nature of Ethernet/IP clearly shows that this technology is aimed at the controller to controller level. The synchronization capabilities of CIP Sync are suitable for synchronizing motion controllers, but the communication performance is not sufficient for closed loop servo drive communication. Industrial Ethernet Technologies Page 45 © EtherCAT Technology Group, August 2011 CIP Motion + CIP Sync Classification Enhances CIP networks for motion control Profinet • Ethernet/IP Premise: Full duplex, switched Ethernet with QoS Prioritization, IEEE 1588 Synchronization and time stamped data transmission is deterministic enough for motion control Ethernet/IP • Motion Control Device Profile included in CIP Spec since 2006 CC-Link IE Sercos III Powerlink Modbus/TCP • First products shown in fall 2009, started shipping in 2010 • Performance limitation of Ethernet/IP leads to trajectory generator in drive • Same approach as with legacy non-motion fieldbus systems EtherCAT Summary © EtherCAT Technology Group Beginning of 2006, ODVA announced an initiative to enhance the CIP protocols by CIP Motion for motion control over Ethernet/IP. ODVA acknowledges that three main ingredients are required: Synchronization services: for this purpose IEEE1588 time synchronization (CIP Sync) will be employed Timely Data Transfer: The goal is to use standard Mechanisms to ensure this: - Full-Duplex 100-BaseT or 100BaseF “Fast” Ethernet. - Ethernet switches to eliminate collisions. - QoS frame prioritization to eliminate queuing delays Motion Control Device Profiles: have been added in V3 of the CIP spec. The goal is to achieve high-performance motion control over standard, unmodified, Ethernet. Even though ODVA aims to achieve timely data transfer in the sub-millisecond cycle time range, this is in total contradiction to the “real life” Ethernet/IP performance. It may be possible to achieve sufficient results in very small, isolated and well engineered networks with carefully selected components. But real life applications will almost certainly be limited to open loop motion control with the trajectory generator in the drive – which is also possible with legacy fieldbus systems like DeviceNet. Whilst the CIP Motion Device Profile is mapped to Ethernet/IP only (and not to DeviceNet, ControlNet), most parameters and mechanisms of the profile clearly have been included to compensate for lack of short cycle times: they describe local trajectory generation. Compared to other drive profiles of IEC 61800-7, the profile is therefore rather complex. Introducing CIP Motion products implies that Rockwell – a Sercos vendor in the past – has turned down Sercos-III and tries to push an own motion bus approach. Industrial Ethernet Technologies Page 46 © EtherCAT Technology Group, August 2011 CIP Motion + CIP Sync Classification Profinet Ethernet/IP CC-Link IE Sercos III Powerlink Modbus/TCP EtherCAT CIP Motion Profile: ongoing project C • At the ODVA general assembly in 2009, major changes in the CIP Motion Profile were announced, since the requested performance could not be achieved with the original version of the spec • Among other changes, Host CPU CIP Motion Object CIP the Startup Procedure was modified TCP UDP 1588 • The Drive-to-Controller IP Process Data assembly was reduced from 120(!) Ethernet MAC Bytes to 36 Bytes • It is now recommended CIP Motion Hardware Assist FPGA to use a „CIP Motion BRP Ring CIP Motion Assist Hardware Assist FPGA“ Support Support (Packet Extraction / Insertion) for implementing a CIP Motion drive Embedded 1588 Assist • Thus CIP Motion now (Time Stamping) Switch Support a Class C approach PHY Summary PHY © EtherCAT Technology Group It is interesting that ODVA now recommends to use an FPGA for implementing the protocol: at the 2007 ODVA general assembly the presentation “Why CIP Motion, Why Now?” claimed that CIP Motion – unlike its competitors – was using “COTS Ethernet hardware, no proprietary ASICs or processors”. First CIP Motion products were previewed at the Rockwell Automation Fair in November 2009 and became available in 2010. In September 2010, RA published a comprehensive CIP Motion Reference Manual (286 pages) and a CIP Motion Configuration and Startup user manual (298 pages). See also: http://www.odva.org/Portals/0/Library/CIPConf_AGM2009/2009_CIP_Networks_Conference_Technical_Track_CIP_ Motion_Implementation.pdf Industrial Ethernet Technologies Page 47 © EtherCAT Technology Group, August 2011 Ethernet/IP Complexity Classification Profinet Ethernet/IP CC-Link IE Sercos III Powerlink Modbus/TCP EtherCAT • In July 2011, Cisco and Rockwell Automation published a Design and Implementation Guide for Plantwide Ethernet/IP Networks. • The document has 548 (!) pages and specifically addresses Plant Managers and Control Engineers as well as IT Managers. • One can either consider this guide • a pretty voluminous manual, or • an indicator for the complexity of implementing Ethernet/IP in manufacturing environments Summary © EtherCAT Technology Group Industrial Ethernet Technologies The guideline (ENET-TD001D-EN-P) can be found here: http://literature.rockwellautomation.com/idc/groups/literature/documents/td /enet-td001_-en-p.pdf Or here: http://www.cisco.com/en/US/docs/solutions/Verticals/CPwE/CPwE_DIG.p df Industrial Ethernet Technologies Page 48 © EtherCAT Technology Group, August 2011 Ethernet/IP Summary Classification Profinet Ethernet/IP CC-Link IE Sercos III Powerlink Modbus/TCP EtherCAT Conclusions: • Network made for many Bytes of information per connection • Initially not intended for Drives and I/O (Bit-sized connections) Technical Issues: • Performance not convincing („use ControlNet“) • Ethernet/IP uses broadcast telegrams • requires complex router configuration (e.g. IGMP snooping) to avoid frame flooding of connected manufacturing and corporate networks • Filter algorithm implementations differ within switches, therefore IT specialist may be needed in real life situations Strategic Issues: • Relatively slow adoption rate outside Rockwell world Summary © EtherCAT Technology Group Industrial Ethernet Technologies A quote from a Rockwell employee: if you need more performance, use Controlnet... Adoption rate: as of August 2011, about 12 years after publication of the spec, the ODVA website listed 100 “non Rockwell”- product guide entries (141 altogether), out of which 27 are switches, cables and connectors. For comparison: 6 ½ years after publication of the spec, the EtherCAT (ETG) website lists 272 “non-Beckhoff” product guide entries (308 altogether, 14 switch, media converter, cable and connector entries). Industrial Ethernet Technologies Page 49 © EtherCAT Technology Group, August 2011 CC-Link IE: Overview Classification Profinet Ethernet/IP • CC-Link is the legacy Fieldbus developed by Mitsubishi in 1997 and since 2000 promoted by CC-Link Partner Association (CLPA) • CC-Link IE: „IE“ stands for Industrial Ethernet • Follows Approach C – needs special interface chips. C CC-Link IE Sercos III Powerlink Modbus/TCP EtherCAT Summary © EtherCAT Technology Group Industrial Ethernet Technologies Source: CLPA Brochure Nov 2010, www.cc-link.org CC-Link is an RS485 based fieldbus technology introduced by Mitsubishi Electric in 1997. In 2000, the CC-Link Partner Association (CLPA) was founded, and since then CC-Link is promoted as an open technology. CC-Link is intended for I/O type communication – not for motion control (for this purpose Mitsubishi uses SSCNET). CC-Link LT is the CLPA technology focusing on simplified wiring and intended for simple I/O devices; it competes with Componet and AS-Interface. CC-Link Safety is the CLPA network for functional safety. Unlike other functional safety protocols, CC-Link Safety is not making use of the “black-channelapproach” but requires a separate network: CC-Link Safety cannot be transported via CC-Link or CC-Link LT. CC-Link IE is the Industrial Ethernet technology of CLPA. There are two versions: 1.CC-Link IE Control (also named CC-Link IE Controller) is intended for controller/controller communication 2.CC-Link IE Field is intended for I/O type communication (similar to CC-Link). The 3rd CC-Link IE version, CC-Link IE Motion, is on the roadmap. In July 2011 a Functional Safety Protocol for integration into CC-Link IE Field was announced by CLPA. Industrial Ethernet Technologies Page 50 © EtherCAT Technology Group, August 2011 CC-Link IE Control: Overview Classification Profinet Ethernet/IP • CC-Link IE Control: for Controller/Controller communication (CLPA: „in-factory backbone“) • Media Access Control: Token Passing • One Control Station, up to 119 Slave Stations • Process Images exchanged by Shared Memory Approach CC-Link IE Sercos III Powerlink Modbus/TCP EtherCAT Summary © EtherCAT Technology Group Industrial Ethernet Technologies Source: CLPA Brochure Nov 2010, www.cc-link.org Token Passing Approach: A CC-Link IE network consists of a single control station and multiple slave stations. As in standard token passing networks, the control station manages the network and starts the token passing sequence by sending the token to the first slave station on the network. The slave station that receives the token performs its cyclic transmission, and then passes the token to the next station in the sequence. After the last slave station completes the process, it passes the token back to the CC-Link IE control station where the entire sequence is started again. A general problem of Token Passing is the error recovery: if the token frame is lost for any reason, the entire token passing system has to be reconfigured – of course the real time behavior is then gone temporarily. Industrial Ethernet Technologies Page 51 © EtherCAT Technology Group, August 2011 CC-Link IE Control: Protocol ¾Classification • CC-Link IE Frame is embedded in Ethernet Frame ¾Profinet • Frame layout is configured at boot up and fixed at run-time ¾Ethernet/IP • Token holder writes to pre-assigned area of the frame • Frame Format is not published ¾CC-Link IE ¾Sercos III ¾Powerlink ¾Modbus/TCP ¾EtherCAT ¾Summary © EtherCAT Technology Group Industrial Ethernet Technologies Source: CLPA Brochure 2009, www.cc-link.org The CC-Link IE Control frame is directly embedded in the Ethernet frame. In addition to the MAC address there is a node number and a network (in the CC-Link IE Header), which are primarily used for addressing. Unfortunately the CLPA CC-Link IE Control specification does not cover the transport layer and the network layer, protocol details are not published. According to an article published by CLPA Europe (IEB Issue 49, November 2008), “TCP/IP communications is supported by way of the transient/acyclic communication function.” However, the specs do not mention this option – it seems that the authors refer to the SLMP over TCP/IP option (see below). Industrial Ethernet Technologies Page 52 © EtherCAT Technology Group, August 2011 CC-Link IE Control: Topology Classification Profinet Ethernet/IP • Topology: Ring • Ring Topology provides Cable Redundancy • Physical Layer: 1000BASE-SX Multimode Optical Fiber 50/125µm (IEEE 802.3) • Connectors: LC Connectors (Duplex) LC Duplex Connector CC-Link IE Sercos III • Max Distance between nodes: 550m • Up to 120 nodes per network, multiple networks can be coupled Master Slave Slave Slave Slave Slave Slave Slave Powerlink Modbus/TCP CC-Link IE Control cannot make use of existing Ethernet Backbone: requires separate Network EtherCAT Summary © EtherCAT Technology Group Industrial Ethernet Technologies Picture: Wikimedia Commons Unlike most other Industrial Ethernet technologies, which use a standard Ethernet network (which is in place in many factory automation environments already), CC-Link IE Control needs a dedicated and separate network of its own. Only ring topology is supported – switches cannot (and need not) be used. CC-Link IE Control products may limit the max. no of nodes. Example: as of 8/2011, only one Mitsubishi CC-Link IE Control Interface supports 120 nodes, the others support 64 nodes. Industrial Ethernet Technologies Page 53 © EtherCAT Technology Group, August 2011 CC-Link IE Control: Implementation Classification • CC-Link IE Control requires special interface ASIC by Mitsubishi, standard Ethernet MACs cannot be used. Profinet • ASIC is not mentioned on CLPA or Mitsubishi Ethernet/IP Websites and Brochures • CC-Link IE Control Specification is available for CLPA Members CC-Link IE on request: Sercos III • Spec is very „lean“, data link layer is missing, interface Powerlink ASIC not mentioned For third parties, implementation of CC-Link IE Control obviously is not enouraged Modbus/TCP EtherCAT Summary © EtherCAT Technology Group Industrial Ethernet Technologies The information about the special ASIC is difficult to find: neither the CC-Link IE website, nor the brochures nor the spec provide any information about this fact. Also, detailed information regarding the CC-Link IE Control chip – which is not the same as the CC-Link IE Field chip CP220 - itself is not available. „Lean“ Specification (as of August 2011, CLPA distributes the first version of the spec, dated Dec 2007): •Device Profile Spec: 1 page •Implementation Rules Spec: 3 pages •Application Layer Service Definition: 41 pages •Application Layer Protocol Definition: 115 pages •Communication Profile Specification: 2 pages The application layer specs are relatively comprensive as they have been prepared for inclusion in IEC61158 – CC-Link IE is going to be type 23. Publication of the edition of this standard containing CC-Link IE is expected for end of 2013. Data link layer/transport layer/network layer with key features such as boot-up, network management and error control are not specified. The Implementation Rules Spec, the Device Profile Spec and the Communication Profile Specs are not sufficient for implementing the technology, the chip seems not to be available outside Mitsubishi. The 2011 presentation „How to Develop CC-Link Compatible Products – Overview“ of CLPA Europe does not mention CC-Link IE at all. Thus the conclusion is that, four years after the introduction of CC-Link IE Control as open network technology, the implementation of CC-Link IE Control is not encouraged – if not impossible – for third parties, at least not outside Japan. CC-Link IE Control thus cannot be considered an open technology. Industrial Ethernet Technologies Page 54 © EtherCAT Technology Group, August 2011 CC-Link IE Control: Performance Classification Performance Examples: Profinet Ethernet/IP CC-Link IE Sercos III 100 MBit No of Nodes Size of exchanged I/O process image per node [Bytes] No of Devices with asynchronous Communication Link Scan Time (=Cycle Time) [ms] EtherCAT [ms] 8 128 0 1,6 0,1 16 256 0 2,0 0,37 16 256 16 3,0 0,42 32 32 32 4,8 0,14 50 64 50 7,9 0,34 256 50 8,0 1,25 50 Powerlink Gbit Cycle Time Computed with Formulas from Mitsubishi Reference Manual CC-Link IE Controller Network Modbus/TCP EtherCAT • CC-Link IE Control Cycle Time is sensitive to number of nodes, but hardly influenced by amount of data exchanged. • Link Refresh Times αT+ αR (Σ typically 1..2ms) and Line Control Time Nc (50…100ms) were not considered. Summary © EtherCAT Technology Group Industrial Ethernet Technologies Due to using Gigabit Ethernet physical layer, CC-Link IE Control cycle time is hardly influenced by the amount of data exchanged. In contrast, due to its functional principle, EtherCAT is hardly influenced by the number of nodes – and is much faster anyhow, in spite of using 100Mbit technology. In order to have a fair comparison, the dedicated and separated CC-Link IE Control network was compared with a dedicated and separated EtherCAT (Device Protocol) network, which can also be used for controller/controller communication. However, in many cases the EtherCAT Automation Protocol (EAP) will be used for that purpose, since EAP can be transmitted via an already existing Ethernet backbone (which is of course not limited to 100Mbit/s). Since EAP is making use of standard Ethernet switch technology, the EtherCAT cycle times listed above are not achieved with this approach. The Link Scan Time (=Cycle Time) formula used was taken from Chapter 7.1 (Link Scan Time) of the “MELSEC Q series/Programmable Controller/Reference Manual (CC-Link IE Controller Network)” SH(NA)-080668ENG Version E of 01.10.2008. We used formula (1) with LY=0, T=2 (default value) and the Line Control Time Nc (Time required for reconfiguring the data link when network is disconnected and reconnected) =0. Usual values for Nc given in that manual are 50ms (Normal) and 100ms (Worst). For error case considerations this time has to be added. For Cyclic Transmission Delay Time the Link Refresh Times have to be taken into account as well. Industrial Ethernet Technologies Page 55 © EtherCAT Technology Group, August 2011 CC-Link IE Field: Overview Classification Profinet • • • • CC-Link IE Field: for I/O type communication Media Access Control: Token Passing All Frames are broadcasted (Switches act like Hubs) One Control Station, up to 120 Slave Stations Ethernet/IP CC-Link IE Sercos III Powerlink Modbus/TCP EtherCAT Summary © EtherCAT Technology Group Industrial Ethernet Technologies Source: CLPA Brochure Nov 2010, www.cc-link.org CC-Link IE Field is the adaptation of CC-Link IE Control to the field level. The functional principle – token passing - is shared by both variants. CCLink IE Field uses copper based Gigabit Ethernet, and supports non-ring topologies such as star and line. 120 Slave stations: the specification allows for up to 253 slave devices; however, current implementations only support 120 slave devices. Industrial Ethernet Technologies Page 56 © EtherCAT Technology Group, August 2011 CC-Link IE Field: Frame Types Classification • CC-Link IE Frames are directly embedded in Ethernet Frame • There are three basic frame types Profinet Transient Transmission Frame, for acyclic Parameter Communication Ethernet/IP CC-Link IE Cyclic Transmission Frame, for process data exchange Sercos III Powerlink Transmission Control Frame, for Token Passing and Network Management EtherCAT Ethernet Header 890F Modbus/TCP CC-Link IE Field Network Frame (46..1500 Bytes) CRC Summary © EtherCAT Technology Group Industrial Ethernet Technologies CC-Link IE Field uses Ethernet frames according to IEEE 803.2 and the Ethertype 0x890F. As of August 2011, the CC-Link IE Field Data Link Layer specification contains no further information than this. The format of the transmission control frame, of the transient transmission control frame and the cyclic transmission control frame are not published. Industrial Ethernet Technologies Page 57 © EtherCAT Technology Group, August 2011 CC-Link IE Field: Phases Classification Profinet Ethernet/IP CC-Link IE Sercos III Powerlink Modbus/TCP EtherCAT CC-Link IE Field has three communication phases a)Initialization Phase: Master establishes Token Passing Route 1. Master finds Slave Devices 2. Master collects information about Slaves 3. Master distributes Token Passing Route 4. Master distributes Parameters 5. Master instructs Slaves to reflect the Parameters 6. Master verifies Slave Parameter Reflection Status b)Refresh Phase: Cyclic and Acyclic Data Exchange 1. Each node, after receiving Token, first sends Status Frame 2. Then sends Cyclic Data Frame(s) 3. Then sends Acyclic Data Frame(s) 4. Then sends Token frame to next Token holder c)Return Phase: New nodes are detected and included in Token Passing Scheme. Master decides when to start Return Phase. Summary © EtherCAT Technology Group Industrial Ethernet Technologies The CC-Link IE Field specification describes the phases in general and also shows the sequence of frames that are exchanged – but it does not contain the frame formats itself. Industrial Ethernet Technologies Page 58 © EtherCAT Technology Group, August 2011 CC-Link IE Field: Refresh Phase Classification Profinet • Process Data Exchange takes place during Refresh Phase. • Cyclic Transmission size of each node is fixed during runtime. • Upper limit of acyclic frames per node is fixed during runtime. Ethernet/IP CC-Link IE Status Frame Cyclic Transmission Frame Acyclic („Transient“) Transmission Frame Token Frame Cycle („Link Scan“) Master Sercos III Slave 1 Powerlink Slave 2 Token Passing Modbus/TCP Slave 3 EtherCAT Slave 4 Summary © EtherCAT Technology Group Industrial Ethernet Technologies After receiving the token, the slave device first sends its status frame, then one or more cyclic transmission frames, optionally followed by acyclic frames (for the so called transient communication). The number of acyclic frames per node and cycle can be limited in order to avoid cycle time violations. Lastly, the node sends the Token Frame to the next token holder. All Frames are broadcasted: nodes with two ports send all frames to both ports, and switches are used like hubs (making use of broadcast MAC addresses). CC-Link IE distinguishes different node types, which differ by maximum process data size as well as features such as support of acyclic communication: e.g.: •“Remote Device Stations” are limited to 128 bits of cyclic I/O data (+ register data) and do not support client functionality in acyclic communication. •“Remote I/O stations” are limited to 64 bits of cyclic I/O data (no register data) and do not support acyclic communication at all. Industrial Ethernet Technologies Page 59 © EtherCAT Technology Group, August 2011 CC-Link IE Field: Topology Classification Profinet Ethernet/IP • • • • • Topology: Combination of Line and Star Topology, or Ring Physical Layer: 1000BASE-T (IEEE 802.3) Connectors: Shielded RJ-45 Max Distance between nodes: 100m Up to 120 nodes per network, multiple networks can be coupled CC-Link IE Sercos III Powerlink Modbus/TCP EtherCAT Summary © EtherCAT Technology Group Industrial Ethernet Technologies Source: CLPA Brochure Nov 2009, www.cc-link.org The topology of CC-Link IE Field is more flexible than the CC-Link IE Control topology. As of August 2011, ring topology is not supported by (Mitsubishi) CC-Link IE Field products yet. Industrial Ethernet Technologies Page 60 © EtherCAT Technology Group, August 2011 CC-Link IE Field: Implementation Classification • CC-Link IE Field also requires special interface ASIC by Mitsubishi: CP220 (BGA256, 17x17mm) Profinet Standard Ethernet MACs cannot be used. Device-side Hard- and Software • CC-Link IE Field Specification is available for CLPA Members on request: Reception Buffer CC-Link IE Field Communication Control Ethernet MAC interface PHY RJ45 • Spec is pretty „lean“, but more Trafo Powerlink Transmission Buffer Trafo Sercos III Cyclic Communication Buffer and Transient Communication Buffer RJ45 CC-Link IE CC-Link IE Field Controller • ASIC is not (yet) available in Europe PHY Ethernet/IP comprehensive than CC-Link Modbus/TCP IE Control spec. EtherCAT For third parties, implementation of CC-Link IE Field looks challening Summary © EtherCAT Technology Group Industrial Ethernet Technologies CP220 Picture: Mitsubishi Japan Website According to Mitsubishi Electric Germany, the CC-Link IE Field chip CP220 is not (yet) available in Europe. „Lean“ Specification (as of August 2011, CLPA distributes the version BAP 1605 of May 2010): •Device Profile Spec: 8 pages •Implementation Rules Spec: 7 pages •Data Link Layer Spec: 2 lines (not pages) •Application Layer Service Definition: 56 pages •Application Layer Protocol Definition: 153 pages •Communication Profile Specification: 15 pages The application layer specs are relatively comprensive as they have been prepared for inclusion in IEC61158 – CC-Link IE is going to be type 23. Publication of the edition of this standard containing CC-Link IE is expected for end of 2013. With the CP220 manual it may be possible to implement a slave device, but since there is no information about the Data Link Layer a master device cannot be implemented by third parties as of now. Thus the conclusion is that as of August 2011 the implementation of a CC-Link IE Field slave device by third parties is very challenging, at least outside Japan. Industrial Ethernet Technologies Page 61 © EtherCAT Technology Group, August 2011 CC-Link IE: SLMP FTP Profinet • SLMP stands for Seamless Message Protocol HTTP Classification Common Application Protocol, SLMP TCP/UD P IP Ethernet/IP CC-Link Ethernet RS-485 CC-Link IE Sercos III Powerlink Modbus/TCP EtherCAT Summary • SLMP is independent of the data link layer and can be implemented on CC-Link IE and TCP(UDP)/IP • According to CPLA, legacy CC-Link also supports a similar protocol • SLMP supports • Client/Server communication: for remote access to parameters or status information • Remote Control of Devices • Event driven communication („on-demand communication“) © EtherCAT Technology Group Industrial Ethernet Technologies By introducing SLMP aims to install a common protocol layer and thus a “cross-media” communication option for all CC-Link technologies. This can be seen as the attempt to provide an approach similar to CIP (ODVA) – however, SLMP does not contain device profiles. Thus, it may provide a common “how to communicate” protocol, but lacks a “what to communicate” definition. Industrial Ethernet Technologies Page 62 © EtherCAT Technology Group, August 2011 CC-Link IE Field: SLMP Classification Profinet • For devices that do not support a dedicated CC-Link IE Field chip, CLPA suggests using SLMP protocol through TCP/IP SLMP SLMP Ethernet Ethernet TCP IP Ethernet/IP CC-Link IE Sercos III Powerlink Master Switch Slave Slave Ethernet Device Gate way Switch Gbit Slave Slave SLMP Ethernet Device Modbus/TCP Ethernet Device 10/100MBit Ethernet or Gbit Device Ethernet Device EtherCAT Summary © EtherCAT Technology Group Industrial Ethernet Technologies CLPA suggests to use the SLMP via TCP/IP approach for devices such as RFID controllers, HMI, Barcode readers or Vision Sensors. Of course this approach is non-real time. To make this very clear: According to the available specifications, CC-Link IE Field cannot transport other Ethernet traffic such as TCP/IP. The SLMP via TCP/IP approach simply means that the SLMP protocol of CC-Link IE can also be transported via TCP/IP, and Ethernet TCP/IP devices also supporting the SLMP protocol can exchange information with a CC-Link IE network via a gateway. Industrial Ethernet Technologies Page 63 © EtherCAT Technology Group, August 2011 CC-Link IE Field: Performance Gbit 100 MBit Classification Performance Examples: Profinet No of Nodes Size of exchanged I/O process image per node [Bytes] No of Devices with asynchronous Communication Link Scan Time (=Cycle Time) Normal | High Speed Mode [ms] EtherCAT [ms] 8 16 0 0,9 | 0,3 0,03 16 16 0 1,1 | 0,5 0,05 16 16 16 2,2 | 0,6 0,05 32 16 32 3,6 | 0,9 0,09 64 8 64 6,4 | 1,5 0,14 64 16 64 6,5 | 1,6 0,18 64 32 64 6,6 | 1,8 0,26 120 16 120 11,4 | 2,8 0,33 Ethernet/IP CC-Link IE Sercos III Powerlink Modbus/TCP EtherCAT Summary Cycle Time Computed with Formulas from Mitsubishi CC-Link IE Field Network Master/Local Module User‘s Manual • CC-Link IE Field Cycle Time is sensitive to number of nodes, but hardly influenced by amount of data exchanged. • EtherCAT is about 10 x faster than CC-Link IE Field in High Speed Mode © EtherCAT Technology Group Industrial Ethernet Technologies The Mitsubishi CC-Link IE Field Master supports two modes: Normal Mode – which is the default - performs both cyclic and acyclic (transient) transmission without losing their inherent speed performance, while High Speed Mode preferentially performs cyclic transmission for high-speed communications and reduces processing speed for transient transmissions. In High Speed Mode the maximum data size for register communication is reduced. Similar to CC-Link IE Control, the cycle time of CC-Link IE Field is hardly influenced by the amount of data exchanged. In contrast, due to its functional principle, EtherCAT is hardly influenced by the number of nodes – and is much faster anyhow, in spite of using 100Mbit technology. The Link Scan Time (=Cycle Time) formula used was taken from Appendix 5.2 (Link Scan Time) of the “MELSEC Q CC-Link IE Field Network Master/Local Module User’s Manual” SH(NA)-080917ENG-E(1107)MEE of July 2011, found on www.meau.com (Mitsubishi Electric Automation Inc, USA). Please note that it is not (yet) possible to download this manual from within Europe – it looks like you have to have an American IP Address to access it. We used the link scan time formula with Ka=25,8 (Normal Mode)|18,5 (High Speed), Kb=655 (NM)|168(HS), Kc=160+60*(no_of_nodes_with_acyclic_comm)(NM)|80(HS), Ni=0 and Kd (Maximum data link processing time when the station is disconnected from or returned to the network) =0. Using recommended values for Kd leads to additional ~20ms cycle time. For error case considerations this time has to be added. For Cyclic Transmission Delay Time the Link Refresh Times have to be taken into account as well. Industrial Ethernet Technologies Page 64 © EtherCAT Technology Group, August 2011 CC-Link IE: Adoption Rate Classification Profinet Ethernet/IP CC-Link IE Sercos III Powerlink Modbus/TCP EtherCAT CC-Link IE Control: Four years after its introduction, there is no visible adoption of CCLink IE Control outside Mitsubishi: •As of August 2011, the CLPA product guide only lists 2 nonMitsubishi products: both are fibre optic cable. Since the interface ASIC seems not to be available for third parties, the hw costs of a CC-Link IE Control interface cannot be determined. CC-Link IE Field: About one year after its introduction, there is no visible adoption of CC-Link IE Field outside Mitsubishi: •As of August 2011, the CLPA product guide only lists 3 nonMitsubishi products: two cables, one switch. Since the interface ASIC CP220 is not (yet) available in Europe, the hw costs of a CC-Link IE Field interface could not be determined. Summary © EtherCAT Technology Group Industrial Ethernet Technologies HMS Anybus shows a CC-Link IE Field Interface card on its website. According to HMS, it is released for samples. Industrial Ethernet Technologies Page 65 © EtherCAT Technology Group, August 2011 CC-Link IE: Summary ¾Classification ¾Profinet ¾Ethernet/IP ¾CC-Link IE ¾Sercos III ¾Powerlink ¾Modbus/TCP ¾EtherCAT CC-Link IE Control: • Non-open, Mitsubishi-only fiber optic ring network making use of Gigabit Ethernet physical layer. • Requires separate network, transport of TCP/IP and other Ethernet traffic is not specified. • Intended and suitable for shared memory communication between Mitsubishi PLCs. CC-Link IE Field: • Semi-open, so far de-facto Mitsubishi-only Gigabit Ethernet based communication technology. • Rather poor utilization of Gigabit transmission speed, less performance than competing 100Mbit/s technologies such as Profinet. • According to the Spec, other Ethernet traffic (including TCP/IP) cannot be transported trough a CC-Link IE field network ¾Summary © EtherCAT Technology Group Industrial Ethernet Technologies Seems difficult to find a convincing reason why an automation vendor should adopt any CC-Link IE variant – it will be challenging to position CCLink IE as an alternative to existing Industrial Ethernet Technologies. Industrial Ethernet Technologies Page 66 © EtherCAT Technology Group, August 2011 SERCOS III Features Classification Profinet Ethernet/IP CC-Link IE Sercos III Powerlink Modbus/TCP EtherCAT • • • • • • • • • • • • Combining Sercos mechanism with EtherNet Physics 100 MBit network transmission rate Hardware based synchronization and ring topology Integration of NRT channel, e.g. for TCP/IP Cyclic and acyclic communication Cross-communication between slaves Media redundancy support Control recognizes the physical order of devices 100BASE-TX or Fibre Optics based physical layer Hard Real Time Requires Special Master Card maximum of 511 slave nodes per network (since V1.1) Line + Ring Topology, only. Summary © EtherCAT Technology Group Industrial Ethernet Technologies The list of features of SERCOS-III reads like the list of features of EtherCAT – except the last three items. C Industrial Ethernet Technologies Page 67 © EtherCAT Technology Group, August 2011 SERCOS III Functional Principle AT: Drive Telegram Classification NRT: Non Real Time Frames MDT: Master Data Telegram C Profinet AT MDT NRT Ethernet/IP CC-Link IE Sercos III Powerlink Modbus/TCP Master • • • • • Slave Slave Slave Slave Slave Slave Slaves extract and insert data on the fly Master sends frames – 2 or more per cycle Slaves process frames twice NRT data is inserted in gaps (NRT channel) Telegram structure fixed at run time. EtherCAT Summary © EtherCAT Technology Group Industrial Ethernet Technologies SERCOS-III has adopted the EtherCAT functional principle: processing Ethernet frames on the fly. There are some main differences, though: 1. SERCOS-III separates input and output data in two frames – so there are at minimum two frames per cycle 2. The slaves process the data twice: on the way out and on the way back 3. Very rigid frame layout – no changes at runtime, no bit-wise mapping. 4. Non Realtime Data (such as TCP/IP) is inserted in gaps between the frames. These differences have the following impact – compared with EtherCAT: 1. Bandwidth utilization is lower. Dual processing in the slave devices. Therefore in average 2-3 times slower than EtherCAT. 2. Separating input and output data and processing twice allows for topology independent slave-to-slave communication within the same cycle. For topology independent slaveto-slave communication, EtherCAT has to relay the data through the master (performance implementation dependent, can also be done with 2nd frame within in the same cycle). However, since Servos III overall cycle time is higher, slave-to-slave performance is not better than with EtherCAT. 3. Due to the „processing twice“ principle, only line topology (+ ring for redundancy) are possible: no drop lines, tree configuration etc. 4. No flexibility in process data communication: same update rate for all nodes and data. 5. If the IP gap is shorter than the maximum Ethernet frame length (< 122 µs), the MTU (Ethernet Maximum Transmission Unit) has to be adapted accordingly: the device interfacing Ethernet to Sercos III has to handle the fragmentation, similar to an EtherCAT switchport. Industrial Ethernet Technologies Page 68 © EtherCAT Technology Group, August 2011 SERCOS III Topology Classification Master Master ... SERCOS-IIIInterface Profinet S ... Slave ... Primary Ring Ethernet/IP CC-Link IE ... redundant secondary Ring ... ... S1 S1 Sercos III S2 S2 Sn Sn Powerlink Modbus/TCP EtherCAT Summary Line structure (single ring) © EtherCAT Technology Group Ring structure (double ring) Industrial Ethernet Technologies SERCOS-III supports line and ring topology, only. Ring structure: Recovery time in case of cable failure < 25µs. No star or tree topology, thus no hot-connect of branches. Industrial Ethernet Technologies Page 69 © EtherCAT Technology Group, August 2011 SERCOS III Communication Cycle Classification MDT: Master Data Telegram AT: Drive Telegram typically: 1 MDT + 1 AT Telegram per Cycle Profinet Ethernet/IP CC-Link IE Sercos III Powerlink Modbus/TCP EtherCAT If IP Channel used: gap needed Summary Source: Presentation at Real Time Ethernet Seminar, Reutlingen, March 2005 © EtherCAT Technology Group Industrial Ethernet Technologies IP data is inserted in a gap („IP channel“).The gap can either be after the input and output frames (method 1) or in between (method 2). Industrial Ethernet Technologies Page 70 © EtherCAT Technology Group, August 2011 SERCOS III Telegram Structure Classification Profinet Ethernet/IP CC-Link IE Sercos III Powerlink Modbus/TCP EtherCAT Summary Source: Presentation at Real Time Ethernet Seminar, Reutlingen, March 2005 © EtherCAT Technology Group Industrial Ethernet Technologies Once in real time mode, Sercos-III uses the same frame structure in every cycle. Therefore there is no flexibility in process data communication: each node and each process data part is updated at the same rate. It is thus not possible to e.g. cyclically read a status bit of a device and request data only if this status bit indicates new data. Furthermore, since the process data length per node is fixed to either 2,4 or 8 bytes (+ 4 bytes status per device), this approach is not ideal for devices with very small process data images (like digital I/O). Industrial Ethernet Technologies Page 71 © EtherCAT Technology Group, August 2011 SERCOS III Synchronization Classification Profinet Ethernet/IP CC-Link IE Sercos III Powerlink Modbus/TCP EtherCAT Synchronization Accuracy depends on Master Accuracy: hardware support required Summary Source: Presentation at Automation Summit, Beijing, June 2007 Source: Prof. Schwager, FH Reutlingen © EtherCAT Technology Group Industrial Ethernet Technologies Just like with SERCOS-II, synchronization in SERCOS-III is based on cyclic, deterministic and jitter-free communication. This requires special hardware support in the master: a special dedicated SERCOS master card. IEEE1588 support may be added later, but will as well need hw support for accuracy. Industrial Ethernet Technologies Page 72 © EtherCAT Technology Group, August 2011 SERCOS III Synchronization Classification Profinet Ethernet/IP CC-Link IE Sercos III Powerlink Modbus/TCP EtherCAT Announced in April 2007: Soft-Master, suitable if RTOS-Jitter is sufficient for Node Synchronization Summary Source: Presentation at Automation Summit, Beijing, June 2007 © EtherCAT Technology Group Industrial Ethernet Technologies In April 2007, Sercos International announced the development of a Sercos-III “Soft-Master”, implementing the master functionality using software (+ a standard Ethernet Port). According to the press release (quote), ”The achievable synchronization accuracy of a SERCOS III realtime network using a soft master is depending on the performance of the hardware and the characteristic of the used operating system”. Sercos International: • special hardware support for 1µs jitter • soft master for up to 50µs jitter Industrial Ethernet Technologies Page 73 © EtherCAT Technology Group, August 2011 SERCOS III Implementation Classification 1. FPGA solution Profinet Ethernet/IP CC-Link IE Sercos III Powerlink 2. Integrating SERCOS III interface into universal communication controllers Cost effective Makes “single-chip devices” possible Multi-Protocol capability Modbus/TCP EtherCAT Summary © EtherCAT Technology Group Industrial Ethernet Technologies SERCOS-III Controllers are FPGA based. Later a hardcopy version may be added. Alternatively the Hilscher netX chip family can be used, which also supports EtherCAT + Profinet In order to push the adoption of the SERCOS I/O profile (which was published in Nov 2006), Sercos launched Easy-I/O in April 2007), a free IP Core for the Xilinx Spartan-3 XC3S250E FPGA. This code is limited to 64 Byte I/O data, and targeted at encoders, measuring sensors, valve clusters, 24V digital I/O and analog I/O. It is not suitable for Sercos-III drive implementation. As of 1/2011, no product using this free IP-core is listed in the Sercos product guide. For Sercos International (SI) members, a commercial IP core for SercosIII is available for a one time fee. For non members of Sercos International an annual license fee for this IP core applies. Alternatively, run-time licenses are available (non members pay double runtime fees). In April 2009, Sercos International announced to publish a Sercos-III master API under GPL license. The API only supports the SERCON100M Master IP Core (no generic Ethernet MAC). As of Aug 2011, documentation is in German language, only (English version announced). Industrial Ethernet Technologies Page 74 © EtherCAT Technology Group, August 2011 SERCOS III Performance Overview Classification Profinet Ethernet/IP CC-Link IE Sercos III Powerlink Cyclic data 8 12 16 12 32 12 50 32 12 Byte Byte Byte Byte Byte Byte Byte Byte Byte Cycle time No. of slaves (1) 31,25 us 62,5 us 125 us 250 us 250 us 500 us 1 ms 1 ms 1 ms 7 14 26 61 33 122 97 137 251 No. of slaves (2) No. of slaves (3) No. of MDT / AT 30 17 94 85 120 220 2 8 21 57 31 120 95 134 245 1/1 1/1 1/1 1/1 1/1 2/2 4/4 4/4 4/4 1) without NRT channel Modbus/TCP 2) with NRT channel: 1500 bytes = 125 µs 3) with NRT channel: 250 bytes = 20µs EtherCAT Summary Source: Peter Lutz, Sercos International, 29.09.2008 © EtherCAT Technology Group Industrial Ethernet Technologies This performance data was provided by Sercos International in September 2008. At cycle times below 250µs the IP channel is shorter than a maximum frame length, and thus IP traffic is fragmented: MTU (Ethernet Maximum Transmission Unit) has to be adapted accordingly by the gateway. This MTU adaptation is not supported by all gateways – in fact, the only gateway listed in the Sercos product guide as of Aug 2011 does not support this functionality. Industrial Ethernet Technologies Page 75 © EtherCAT Technology Group, August 2011 SERCOS III Performance Comparison Classification Profinet No. of Nodes with given Cycle Time Sercos III Powerlink Modbus/TCP EtherCAT EtherCAT Application Example Cyclic Data (I+O) Cycle Time No. of Devices without IP channel with IP Channel (20µs |125µs) No. of Devices with IP remaining Bandwidth for IP 1 8 Byte 31,25 µs 7 2|- 20 48,1% 2 12 Byte 62,5 µs 14 8|- 40 32,3% 3 16 Byte 125 µs 26 21 | - 72 22,3% 4 12 Byte 250 µs 61 57 | 30 180 25,8% 5 32 Byte 250 µs 33 31 | 17 80 12,2% 6 12 Byte 500 µs 122 120 | 94 400 20,6% 7 50 Byte 1 ms 97 95 | 85 225 6,4% 8 32 Byte 1 ms 137 134 | 120 340 9,1% 9 12 Byte 1 ms 251 245 | 220 800 19,8% Ethernet/IP CC-Link IE SERCOS-III Summary Same Sercos data as previous slide, now in comparison with EtherCAT. © EtherCAT Technology Group Industrial Ethernet Technologies Comparing SERCOS-III and EtherCAT performance: at given cycle times and amount of data per slave, the maximum number of nodes is given for both technologies. Please note that as of Aug 2011, there is no gateway available supporting the shortened IP channel (which would lead to the values marked in green) Industrial Ethernet Technologies Page 76 © EtherCAT Technology Group, August 2011 SERCOS III Performance Comparison Classification Profinet Cycle Time with given No. of Nodes SERCOS-III EtherCAT Cyclic Data (I+O) Cycle Time No. of Devices without IP channel No. of Devices with IP Channel No. of Devices with IP Resulting Cycle Time Ethernet/IP Application Example CC-Link IE 1 8 Byte 31,25 µs 7 2|- 2 10 µs 2 12 Byte 62,5 µs 14 8|- 8 23 µs 3 16 Byte 125 µs 26 21 | - 21 47 µs 4 12 Byte 250 µs 61 57 | 30 57 95 µs 5 32 Byte 250 µs 33 31 | 17 31 106 µs 6 12 Byte 500 µs 122 120 | 94 120 203 µs 7 50 Byte 1 ms 97 95 | 85 95 446 µs 8 32 Byte 1 ms 137 134 | 120 134 435 µs 9 12 Byte 1 ms 251 245 | 220 245 350 µs Sercos III Powerlink Modbus/TCP EtherCAT Summary © EtherCAT Technology Group Industrial Ethernet Technologies Another view for the comparison: now the number of nodes and the amount of data per slave is fixed, and the resulting cycle time is compared. Industrial Ethernet Technologies Page 77 © EtherCAT Technology Group, August 2011 SERCOS III Performance Comparison Cycle Time Comparison Classification 1000 Profinet 900 SERCOS-III 800 Ethernet/IP Sercos III Powerlink Cycle Time [µs] CC-Link IE EtherCAT 700 600 500 400 300 200 Modbus/TCP 100 0 EtherCAT 1 2 3 4 5 6 7 8 9 Application Examples Summary © EtherCAT Technology Group A graphical view for the previous table. In average (over 9 different application scenarios), EtherCAT is 2,7 times faster. Industrial Ethernet Technologies Page 78 © EtherCAT Technology Group, August 2011 SERCOS III IP-Handling (I) Classification Profinet Ethernet/IP CC-Link IE Sercos III Powerlink Modbus/TCP • At Boot-Up, Slaves are in NRT Slave (Non Real Time) Mode until they see first RT Frame • In NRT Mode, Slave Chips Protocol behave like 3-port Switches Handler • Each node needs a MAC Address • The internal Switches are 3 Port implemented with “Store and Switch Forward” or with “Cut Through” methodology • Forwarding Delay depends on No. of Nodes, size of IP or NRT slot, frame size and switch methodology (may differ from node to node) • Typical Store and Forward Delay per Node and Direction: 10…125µs, depending on Frame Length EtherCAT Summary © EtherCAT Technology Group Sercos-III implementations either follow the “store and forward” approach for the switch (NRT) mode, which in case of Sercos-III means that the NRT frame is only forwarded in the next cycle, or the follow the “cut through” methodology, which means that they forward the frame only within the same cycle if after the analysis of the destination address the remaining IP-Slot is able to carry the maximum frame length. It will be interesting to see how the IP communication over a large number of cascaded switches behaves. Industrial Ethernet Technologies Page 79 © EtherCAT Technology Group, August 2011 SERCOS III IP-Handling (II) Classification Profinet for IP Access to Slave Devices via TCP/IP: • Gateway Device or Master with Gateway Functionality Required • or access through open port @ last node in line Ethernet/IP CC-Link IE Gateway Device Sercos III AT Powerlink Modbus/TCP MDT Master IP Slave Slave Slave Slave Slave EtherCAT Summary © EtherCAT Technology Group In order to allow for IP access to slave devices at run-time, either routing through the master or a special gateway device have to be used. This is the same if IP access (e.g. for remote diagnosis) shall be supported without the need to physically connect the link first. If an unused port is available, this can be used alternatively. Since Sercos-III Devices have two ports, in line topology there is one unused port at the last node in the line (no unused port in ring topology) Industrial Ethernet Technologies Page 80 © EtherCAT Technology Group, August 2011 SERCOS III IP-Handling (III) Classification • In RT Mode, IP Traffic is inserted in IP Channel • During IP Channel, Slave is in Switch Mode Profinet AT MDT IP Ethernet/IP CC-Link IE Sercos III Powerlink Modbus/TCP EtherCAT Master Slave Slave Slave Slave Slave Slave • If IP slot is short or slave controller chip works with store and forward methodology, forwarding of larger frames is delayed to the next cycle – in this case sending a frame e.g. to node 50 takes 50 cycles, response frame accordingly (TCP/IP handshake). • IP channel performance strongly depends on No. of Nodes • As of August 2010, Multi IP-Frame Operation not implemented: Within one cycle only one frame can be handled, regardless of IP-channel size Summary © EtherCAT Technology Group In each RT cycle, the slave controllers switch between “processing on the fly-mode” for process data and “switch-mode” for IP data. The forwarding behavior of IP frames in the IP slot depends on the slave device capabilities and on the network configuration Industrial Ethernet Technologies Page 81 © EtherCAT Technology Group, August 2011 Sercos III IP-Channel, Store + Forward Classification Profinet • In NRT Mode, incoming frames are buffered (Collision buffer) • Store + Forward: Frame is buffered until next IP-Channel is active (next cycle) Ethernet/IP Local Application CC-Link IE Sercos III Internal Rx Port 1 Internal Tx Port 1 Internal Rx Port 2 Internal Tx Port 2 Collision Buffer 2 Powerlink Collision Buffer 1 MUX Modbus/TCP EtherCAT Rx Port 1 Tx Port 1 MUX Rx Port 2 Tx Port 2 Example for Sercos-III Chip with Store + Forward Switch: Hilscher NETX Family Summary © EtherCAT Technology Group Current Sercos-III implementations support Store and Forward, which means that in NRT mode within one cycle an IP frame moves from node n to node n+1 Industrial Ethernet Technologies Page 82 © EtherCAT Technology Group, August 2011 Sercos III IP-Channel, Cut-Through Classification • In NRT Mode, incoming frames are buffered (Collision buffer) • Cut Through: Once destination address is received: Profinet • If Tx-Port is not allocated by internal Tx-Port and remaining IP-Slot is > 122µs (max. frame length), frame is forwarded Ethernet/IP • Otherwise: frame is buffered until next IP-Channel is active Local Application CC-Link IE Internal Rx Port 1 Sercos III Internal Tx Port 1 Internal Rx Port 2 Internal Tx Port 2 Collision Buffer 2 Powerlink Collision Buffer 1 MUX Modbus/TCP EtherCAT Rx Port 1 Rx Port 2 Tx Port 2 • If IP slot is ≤125µs, Cut-through also forwards in next cycle, only • Summary Tx Port 1 MUX Example for Sercos-III Chip with Cut-Through Switch: SERCON100 IP Core, for which, as of August 2010, the IP-Channel frame forwarding has not yet been tested. © EtherCAT Technology Group Future Sercos-III implementations plan to support Cut-Through behavior in NRT mode, which means that an IP frame can move several nodes before it is stored for the next cycle. However, if the IP slot is shorter than 125µs, Cut-Through Sercos-III slave controllers will also have to behave like Store-and-Forward implementations and buffer the frame for the next cycle. Industrial Ethernet Technologies Page 83 © EtherCAT Technology Group, August 2011 SERCOS III IP-Performance (I) Classification Profinet Ethernet/IP IP Channel Performance Considerations Best Case Scenario: • All nodes support „Cut Through“-Switch behavior* • IP channel slot longer than: max frame length (122µs) + (No of Nodes x delay per switch) • Then IP frame gets forwarded within one cycle CC-Link IE Sercos III Powerlink Modbus/TCP Example: • Network with 100 Nodes, IP communication with last node (100) • Cycle Time 1 ms, IP Slot 500µs, 12 Bytes I/O data per device • Propagation Delay Master → Node 100: 1 Cycle • Response Time IP Communication (if TCP Connection already established): 2 ms + Stack delay EtherCAT * As of August 2010, Cut Through IP forwarding not yet implemented Summary © EtherCAT Technology Group If IP channel slot is long enough (>>125µs) and cut-through is supported, the performance of the IP communication may be sufficient. However, as of August 2010, according to information on the Sercos Website, the “Cut Through” Switch behavior was not yet implemented. In August 2011 the North American Sercos website claims that there are sercos III products currently on the market that support “Cut Through”. The same website, however, states that the latest release of the Sercos IP Core documentation is from 2009, when this functionality was not implemented yet. Industrial Ethernet Technologies Page 84 © EtherCAT Technology Group, August 2011 SERCOS III IP-Performance (II) Classification Profinet Ethernet/IP CC-Link IE Sercos III Powerlink Modbus/TCP EtherCAT IP Channel Performance Considerations Worst Case Scenario: • All nodes support „Store and Forward“-Switch behavior • IP channel slot is 125µs • Large IP frames are forwarded in next cycle only Example: • Network with 220 Nodes, IP communication with last node (220) • Cycle Time 1 ms, IP Slot 125µs, 12 Bytes I/O data per device • Propagation Delay Master → Node 220: 220 Cycles • Response Time IP Communication (if TCP Connection already established): 440ms + Stack delay • If node implementation only supports forwarding in next cycle, then even establishing a TCP/IP connection takes >660ms (Three Way Handshake) Summary © EtherCAT Technology Group If IP channel slot is short IP communication performance may deteriorate substantially – especially in larger networks. This can be avoided by smart configuration tools, which take the node behavior and network size into account and adjust the IP slot time accordingly. It is obvious, though, that the IP handling mechanism of SERCOS III works best in small networks. Industrial Ethernet Technologies Page 85 © EtherCAT Technology Group, August 2011 SERCOS III V1.1 Classification • In July 2007, SERCOS International released the 1.1 version of the SERCOS-III specification Profinet • Main changes are: Ethernet/IP CC-Link IE Sercos III Powerlink Modbus/TCP EtherCAT - Device addressing changed, now topology dependent - Parameter addressing changed from 16-bit IDN to 32-bit structured EIDN - status + control word format and content changed - Redundancy and hot-plug features introduced - Communication model changed from master/slave to connection oriented - 511 instead of 254 slave devices supported - Mandatory IP channel introduced - Interrupt handling changed, now one Sync-IRQ • The specification changes require hardware adaptations (Sercos controllers) and also major software changes. • Version 1.0 and Version 1.1 devices are not interoperable • First SERCOS-III V1.1 drives were shipped in Dec 2007. Summary © EtherCAT Technology Group Industrial Ethernet Technologies This means that, as of beginning of 2008, Sercos-III field deployment and application experience started all over again. On the other hand, since hardly any Sercos-III devices were shipped before 2008, this does not seem to be a major problem. By introducing 32bit IDNs and thus enhancing the IDN address space, Sercos-III device profiling differs from the profiles used in Sercos-I and –II. Current Sercos III version is V1.1.2, which introduced hotplug capabilities and the support of software implemented masters. Industrial Ethernet Technologies Page 86 © EtherCAT Technology Group, August 2011 SERCOS III V1.3 Classification • In Q3 2011, SERCOS International plans to release the 1.3 version of the SERCOS-III specification Profinet • Main changes to V1.1.2 are: Ethernet/IP • Support of different producer cycle times (multiplexing of I/O data): not necessary any more to update all nodes in the network with the same cycle CC-Link IE • Introduction of an application timestamp: resolution 1 ms, for establishing a system wide application time, not for synchronization Sercos III • 3-buffer mechanism for process data • Introduction of oversampling data types Powerlink • It is intended to maintain downwards compatibility: masters supporting V1.3 should also be able to run V1.1.2 slaves. Modbus/TCP EtherCAT Summary © EtherCAT Technology Group It seems that Sercos-III is not stable yet. Industrial Ethernet Technologies Industrial Ethernet Technologies Page 87 © EtherCAT Technology Group, August 2011 SERCOS III Summary Classification Profinet Ethernet/IP CC-Link IE • High Performance Industrial Ethernet Approach • Focus on drives, so far very limited I/O, sensor, valve etc. support • Topology: line and ring only, no branches, no drop lines, no hot connect of segments. • Not more than 511 nodes per network, therefore modular I/O with bus couplers (and associated delays). • Requires dedicated master-card for hard real time Sercos III Powerlink Modbus/TCP EtherCAT • Soft-Master implementation for jitter up to 50µs • Depending on configuration IP traffic can be slow • Has been the approach that is the latest on the market • Slow adoption rate (few Sercos I/II vendors move to Sercos III) • EtherCAT supports the same device profile + application layer Summary © EtherCAT Technology Group Industrial Ethernet Technologies SERCOS-III achieves a performance comparable with Profinet IRT – and thus sufficient for most applications. Whilst the SERCOS technology has a good reputation for servo drive control, support for I/O, sensors, or other devices is not yet established. Slow adoption rate: So far few support Sercos-III in Servo Drives. And almost all these vendors have EtherCAT drives available. In Nov. 2007, Elau announced support of Sercos-III as system bus. In Nov 2008, Keba did the same. By the way: out of the 34 Sercos-I/II servo drive suppliers, 29 are ETG members. Out of the missing 5 vendors, two discontinued their Sercos business. Out of the 29 ETG members also supporting Sercos I/II, 23 have already shown or announced EtherCAT drives (as of August 2011) Industrial Ethernet Technologies Page 88 © EtherCAT Technology Group, August 2011 Powerlink: Overview Classification Profinet Ethernet/IP CC-Link IE • • • • • • Ethernet Approach originally introduced by B+R Medium Access Control by Polling (similar to Profibus) TCP/IP for Parameters, seperate Process Data Protocol uses Hubs active Master Plug-in-Card required, no Standard NICs soft realtime („open“) mode initially announced for 2005 B Sercos III Powerlink Modbus/TCP EtherCAT Summary © EtherCAT Technology Group Industrial Ethernet Technologies Powerlink replaces the Ethernet CSMA/CD Media Access Control Method by Polling: The master (called managing node) sends a poll request to each slave (called controlled node) which then answers with a response. Hubs (no switches): the Powerlink Spec states: „To fit EPL jitter requirements it is recommended to use hubs“*. Protected real time mode: Since the Powerlink topology (up to 10 nodes in line configuration) violates IEEE802.3 roundtrip delay rules, CSMA/CD does not work in this configuration – so a network designed for protected mode cannot be accessed with standard Ethernet interfaces (not even in non-realtime mode). * In theory switches can be used, but due to the additional latency the network performance would be unacceptable. All performance calculations in the Powerlink spec assume a Hub Delay Time of 500ns – „store and forward“-switches have a delay time of >10µs (for short frames), „cut through“-switches have a delay time (according to Intel) of ~7,5µs. If hubs were replaced by switches with 10µs delay, the cycle time of example 4 in the Powerlink Spec would be increased from 2,34 ms to 19,44 ms. In September 2005, EPSG announced that Micrels new 3-Port switch chip is endorsed for Ethernet Powerlink implementations. However, in Powerlink applications this switch chip is operated in half duplex repeater mode, only. Thus it is a switch chip that supports a hub mode, too. Industrial Ethernet Technologies Page 89 © EtherCAT Technology Group, August 2011 Powerlink: Functional Principle Ethernet/IP CC-Link IE Sercos III Powerlink Master Slave 1 HUB 3 HUB HUB 7 Modbus/TCP 2 HUB HUB Profinet • Polling (Marketing: Time Slice…) • Hubs only, half duplex • Broadcast: every node receives every frame • Thus high Interrupt load and processing requirements • Limited Line Topology (Hub Delays) Slave 4 Slave HUB Classification 5 EtherCAT 6 Slave Slave Slave Summary © EtherCAT Technology Group Industrial Ethernet Technologies Powerlink Marketing calls the Media Access Method „Time Slicing“ or „Slot Communication Network Management“. The principle nevertheless is polling – the controlled device only „speaks“ after it was „asked“. Due to the broadcast nature of hubs, all nodes receive all frames. Therefore the nodes have to filter each frame. The broadcast mechanism can be used for slave to slave communication (consumer/producer principle). However, performance of slave to slave communication cannot be better than the cycle time... The accumulation of the hub delays limits the number of nodes in a line topology. Industrial Ethernet Technologies Page 90 © EtherCAT Technology Group, August 2011 Powerlink Timing • Overall Network Performance depends on Slave Implementation + Topology: Classification • Fast response time requires powerful processors on the slave (controller) side – or implementation in Hardware (FPGA) Profinet • A lot of „idle time“ on the media, caused by stack delays plus cascaded hubs Ethernet/IP Cycle Time CC-Link IE Start of Cyclic (SoC) Sercos III Poll Request (PReq) Tstart = 26…45µs Powerlink ~7µs Propagation Delay (Hubs + Cable) Depends on Topology Poll Response (PReq) for 1…43 Bytes of Process Data Poll Request (PReq) Master Response Time, Depends on Implementation Start of Async (SoA) Async Send (ASnd) TAsyncMax = 152…200µs Modbus/TCP EtherCAT Slave Response Time, Depends on Implementation Summary © EtherCAT Technology Group Industrial Ethernet Technologies The timing (and thus the performance) of a Powerlink network is mainly determined by the topology and the node response times: each poll request first has to get from the master through all hubs (both the external ones and the integrated ones in a daisy chain or line topology) to the destination node, then the node has to process the request, send the response, which then again goes through all hubs back to the master. Only after the master has received the response, he can issue the next poll request. At the end of the cycle there is the asynchronous phase. Industrial Ethernet Technologies Page 91 © EtherCAT Technology Group, August 2011 Powerlink Synchronization Classification Profinet Ethernet/IP CC-Link IE Sercos III Powerlink Modbus/TCP EtherCAT • Powerlink Spec (2.0) says: • At the beginning of each isochronous phase, the Master Node transmits the multicast SoC message very precisely to synchronize all nodes in the network. • Propagation Delay compensation is not available • Thus the synchronization accuracy depends on • Ability of the Master (M) to transmit SoC equidistantly • Ability of the Slave (S) to timestamp SoC precisely • Accumulated Jitter of all hubs between M and S This means: • Powerlink Implementations without special hardware support (such as “openPowerlink”) cannot provide accurate synchronization by design. • Synchronization accuracy is always topology dependent. Summary © EtherCAT Technology Group Industrial Ethernet Technologies Furthermore, the cycle time setting must provide sufficient leeway for accumulated response jitter of all nodes and for repeating corrupt messages. EPSG announced several times (also in the V2.0 spec of 2006) that precise synchronization using IEEE1588 time precision protocol will be added in V 3.0 – however, as of August 2011, there is no such V 3.0 in sight. Industrial Ethernet Technologies Page 92 © EtherCAT Technology Group, August 2011 Ethernet/IP Drive Drive Drive Profinet Master Drive Application Example: • 6 Drives • 2 I/O Nodes • 400 m Cable Length • Cycle Time: 291 µs Drive Classification Drive Powerlink Performance (I) HUB HUB HUB HUB HUB HUB I/O I/O HUB HUB CC-Link IE Sercos III Powerlink For Comparison: • Sercos II (16 Mbaud): < 250 µs Modbus/TCP • EtherCAT: 17 µs. EtherCAT Summary © EtherCAT Technology Group Industrial Ethernet Technologies This performance example is taken from the Powerlink V 2.0 specification, Version 0.1.0. In this version of the spec, the -slave response time = 8µs -master response time = 1µs (!) -TAsyncMax = 90µs -TStart = 45µs -THubDelay = 0,5µs and the resulting Cycle Time is 291 µs. In Powerlink V 2.0 specification Version 1.0.0, (which is the current one), this performance example is not available any more. However, the performance examples in this version assume -slave response time = 1µs (!) -master response time = 1µs (!) -TAsyncMax = 120+32 (=152)µs + maximum signal propagation -TStart = 26µs -THubDelay = 0,5µs Applying these values to the performance example shown above leads to a Cycle Time of 281 µs. However, the Powerlink Spec does not demand any specific slave response time, and manuals or data sheets of Powerlink products typically do not provide that value. Meanwhile most B&R Powerlink products are FPGA based and thus provide a short response time – since there are few “non-B&R” Powerlink products, such a short response time may be assumed. However, we have seen Powerlink drives in a multivendor motion control demonstrator (equipped with a network analyzer tool) on an EPSG booth with a response time of 10..20µs. Industrial Ethernet Technologies Page 93 © EtherCAT Technology Group, August 2011 Powerlink Performance (II) Classification Master Profinet Drive Drive Drive Drive Drive Drive Drive Drive HUB HUB HUB HUB HUB HUB HUB HUB Drive Drive HUB HUB Drive Drive Drive Drive Drive Drive Drive Drive HUB HUB HUB HUB HUB HUB HUB HUB … Total of 500 m Cable 40 Ethernet/IP CC-Link IE Sercos III Powerlink Modbus/TCP EtherCAT I/O I/O I/O I/O I/O I/O I/O I/O HUB HUB HUB HUB HUB HUB HUB HUB I/O I/O HUB HUB … 50 I/O I/O I/O I/O I/O I/O I/O I/O HUB HUB HUB HUB HUB HUB HUB HUB Cycle Time with 8 µs Slave Response: 2347 µs Cycle Time with 1 µs Slave Response: 1767 µs Summary © EtherCAT Technology Group Industrial Ethernet Technologies This performance example is referenced in the EtherCAT introductory presentation, it is taken from the Powerlink V 2.0 specification, Version 0.1.0. In this version of the spec, the -slave response time = 8µs -master response time = 1µs (!) -TAsyncMax = 90µs -TStart = 45µs -THubDelay = 0,5µs and the resulting Cycle Time is 2347 µs. In Powerlink V 2.0 specification Version 1.0.0, this performance example is not available any more. However, the performance examples in this version assume -slave response time = 1µs (!) -master response time = 1µs (!) -TAsyncMax = 120+32 (=152)µs + maximum signal propagation -TStart = 26µs -THubDelay = 0,5µs Applying these values to the performance example shown above leads to a Cycle Time of 1767 µs. EtherCAT cycle time for this setup would be 276µs if one waits for the frame to return before the next one is sent out, or 125µs if one does not wait (unlike Powerlink, EtherCAT is full-duplex) Industrial Ethernet Technologies Page 94 © EtherCAT Technology Group, August 2011 Powerlink Performance (III) Classification Profinet Topology Dependency of Powerlink Performance Performance Example 2 in the current Powerlink Spec comes in two topology options: star and daisy chain Ethernet/IP CC-Link IE Sercos III Powerlink Modbus/TCP Star Topology, 53 nodes: Cycle Time 999 µs Daisy Chain Topology, 53 nodes: Cycle Time 1967 µs EtherCAT Summary Source: ETHERNET Powerlink V2.0 Communication Profile Specification Version 1.0.0 © EtherCAT Technology Group Industrial Ethernet Technologies This performance example assumes a slave response time of 1µs (!) and a master response time of 1µs (!) With EtherCAT the topology influence on the cycle time is negligible, the cycle time for separate 53 nodes with the same amount of data is 149µs (@50% bus load). Industrial Ethernet Technologies Page 95 © EtherCAT Technology Group, August 2011 Powerlink Interface Costs (I) Classification • Originally, Powerlink claimed to use „standard Ethernet chips only“ Profinet Ethernet/IP CC-Link IE • But: Performance of Software implemented Protocol-Stack unsatisfactory e.g. Net+50 XScale425 Hyperstone Host 2 k DPRAM 128 kB SRAM 32 bit CPU, e.g. ARM7, NIOS 512 kB Flash Ethernet MAC Sercos III • Nodes need a 32 bit CPU and infrastructure Hub Chip / FPGA Powerlink Modbus/TCP • Furthermore, Hub Chips became bsolete -> ASIC or FPGA required PHY PHY Trafo Trafo RJ45 RJ45 EtherCAT Summary © EtherCAT Technology Group Industrial Ethernet Technologies This hardware block diagram was drawn by an EPSG member company and shows the hardware effort for a Powerlink interface based on standard chips. The discrete design of a Powerlink slave interface is not a very cost efficient approach. Industrial Ethernet Technologies Page 96 © EtherCAT Technology Group, August 2011 Powerlink Interface Costs (II) Classification Profinet Ethernet/IP CC-Link IE Sercos III • Since discrete Interface is – too slow – too unpredictable – way too expensive • Powerlink moved to FPGA implementation • so: now HW-Situation similar to PROFINET, SERCOS III and EtherCAT Host 2 k DPRAM z.B. 128 kB SRAM Net+50 32 bit CPU, z.B. ARM7 512 kB Flash FPGA Ethernet MAC Hub Chip / FPGA Powerlink Modbus/TCP B C PHY PHY Trafo Trafo RJ45 RJ45 EtherCAT Summary © EtherCAT Technology Group Industrial Ethernet Technologies EPSG is now supporting different implementation possibilities – the most cost effective is the FPGA solution. It uses the same Altera FPGA that is used for EtherCAT as well, but requires additional 10ns 256k x 16 SRAM. In November 2007, IXXAT, B&R + Lenze announced that the master (managing node) is now also implemented in an FPGA. The rationale is, according to a press statement*: “Until now on the control side there were only solutions which had limited performance and which were not suitable or too expensive for extremely demanding applications such as highly dynamic motion systems, since very powerful CPUs are used.” * Translated from the Article “Master-FPGA für Powerlink”, Computer&Automation Magazine 12/2007, p.17 Industrial Ethernet Technologies Page 97 © EtherCAT Technology Group, August 2011 Powerlink: Versions Classification Network Version Feature Availability Profinet Powerlink Version 1 • Protected mode only • Half Duplex Polling (Hubs) Available by B&R only Ethernet/IP Powerlink Version 2 • • • • • • • Spec: 2003 • Devices Shipping: 2007 Powerlink Version 3 • New protocol principle: Burst Polling • Switched Gbit Ethernet Based • IEEE1588 synchronization CC-Link IE Sercos III Powerlink Modbus/TCP EtherCAT Summary © EtherCAT Technology Group Network Management New Frame Structure MAC-Addressing Asynchronous Channel TCP/IP Support Bridge / Router Support Profile Support (CANopen) Announced 2006 First outline 2009 Spec: ??? • Devices Shipping: ??? Industrial Ethernet Technologies Powerlink Version 1 products are available from B&R only. Powerlink Version 2: Lenze Drives (founding member of Ethernet Powerlink Standardization Group and driving force behind V2) started shipping first Powerlink Products End of 2006. Lenze has meanwhile moved to EtherCAT as system bus (Powerlink may remain in use for applications in which there is no controller, just networked drives) Powerlink Version 3 (Gigabit Powerlink) was announced in November 2006. Lenze is not contributing to Powerlink V3, which seems to be B&R driven. In 2009 B&R published an article describing the functional principle (see next slides) and announced products for 2011. As of August 2011, no Gigabit Powerlink specification has been published (neither within EPSG nor externally), and the most recent publication mentioning Gigabit Powerlink on the EPSG Website is from 2008. Industrial Ethernet Technologies Page 98 © EtherCAT Technology Group, August 2011 Powerlink V3: Gigabit Powerlink (I) Classification Profinet Ethernet/IP CC-Link IE Sercos III • In November 2006, EPSG announced the next version of the technology: Gigabit Powerlink • Initially EPSG publications suggested that they would not risk another version issue and move the existing technology to Gigabit Ethernet • However, in 2/2009 B&R published the new functional principle of Powerlink V3 (Gigabit Powerlink): • Switches instead of Hubs Powerlink • New Process Data Protocol Principle: Poll Request Bursting Modbus/TCP • New Asynchronous Protocol Handling EtherCAT Summary • Synchronization with IEEE 1588 • As of August 2011, there is no Gigabit Powerlink Spec available. © EtherCAT Technology Group In November 2006, EPSG announced Gbit Powerlink as a simple hardware modification (Quote from Powerlink “Facts” 1/2007: “POWERLINK users can easily boost network performance by a factor of 10. Changing the hardware platform to include 1 Gigabit hardware instead of 100 Mbit components is all any developer must do, resulting only in a somewhat different list of components to be fitted onto an otherwise identical PCB.”) However, this approach was later abandoned: Doing the math's shows that the performance gain would have been minimal. Depending on the configuration, a factor of 1.38…2 was to be expected, since most of the Powerlink cycle time is made up by stack delays which are not influenced by bandwidth increase. Furthermore, moving on to switches increases the forwarding delay within the infrastructure substantially, which would have over-compensated the bandwidth increase. So in 2/2009 it was announced that Powerlink V3 will be based on a new functional principle (see next slide). Many device vendors postponed their Powerlink implementation plans since V2 was already outdated in 2006/2007, and Gigabit Powerlink not yet specified. Industrial Ethernet Technologies Page 99 © EtherCAT Technology Group, August 2011 Powerlink V3: Gigabit Powerlink (II) Classification Profinet Powerlink V2: Polling (Half Duplex) SoC PReq S1 PRes S1 Ethernet/IP CC-Link IE Sercos III PReq S2 PRes S2 PRes M PRes S3 SoA 100 MBit/s ASnd Sn Powerlink V3: Burst Polling (Full Duplex) SoP PReq S1 PReq S2 PReq S3 PRes M PRes PRes PRes S1 S3 S2 Powerlink Modbus/TCP PReq S3 1 GBit/s ASnd Sn • In Powerlink V3 all Poll Requests will be sent immediately (Burst) EtherCAT • The slave devices will answer as quickly as possible – collisions are avoided by the switches, who sort the responses in queues. Summary • The asynchronous bandwidth will be allocated with the help of the Start of Cycle frame – the Start of Asynchronous Frame is omitted. © EtherCAT Technology Group As with the change from Powerlink V1 to V2, the announced version V3 will change both the protocol and the cyclic behavior of the network. Hence downwards compatibility cannot be expected. Hubs will be replaced by switches, and instead of individual polling a “burst polling” approach will be introduced. The “Start of Asynchronous” Frame will be abandoned, its functionality will be included in the “Start of Protocol” (SoP) Frame, which replaces the “Start of Cycle” frame of Powerlink V2. A node that wants to send an asynchronous frame informs the master by flagging this in its poll response frame. With the next SoP frame the master then allows the node to send such a frame. Other than with Powerlink V2, asynchronous frames are thus postponed to the next cycle. The “poll response” frames are going to be sent with broadcast MAC addresses –this preserves the slave-to-slave communication but puts substantial load on all devices, which have to filter all poll responses. Furthermore, this means that for half of the traffic the switches sacrifice their routing capabilities and become “slower hubs”. For synchronization with IEEE 1588, the sync frame of the 1588 protocol is included in the SoP frame. All switches have to support the IEEE 1588 peer-to-peer, one-step transparent clocks in hardware. Thus special switches are required. The shortest cycle time is either determined by the sum of frames sent by the master, or by the sum of frames sent by the slaves, or by response time and the overall propagation delay of the farthest slave device (including the switch delays). It is thus still difficult to predict and influenced by protocol stack performances, topology and the performance of the infrastructure components. Industrial Ethernet Technologies Page 100 © EtherCAT Technology Group, August 2011 Powerlink V3: Gigabit Powerlink (III) Classification • Another incompatible Powerlink Version Profinet • Resulting Cycle Time difficult to determine - depends on topology, switch performance and slave implementation Ethernet/IP CC-Link IE Sercos III Powerlink • Synchronization requires Switches with 1588 Support • Gigabit issues remain: • 8 instead of 4 Wires (Field Mounting?) • Power consumption significantly higher (PHY + MAC) • Hardly any experience with Gbit inside machine control environments Modbus/TCP • First products originally announced by B&R for 2011, but as of August 2011, no products have been shown. EtherCAT • Functional Principle was introduced in 2001 by Beckhoff („RT-Ethernet“ – a predecessor of EtherCAT) Summary © EtherCAT Technology Group According to a B&R customer presentation (July 2008), the R&D phase for Powerlink V3 (Gigabit Powerlink) products is scheduled for 2009/2010, and first products are planned for 2011. However, according to the slides of the May 2011 B&R Powerlink Day, Gigabit Powerlink was not even mentioned any more. In Gigabit mode, MACs and PHYs consumer about 6 times as much power as in 100 Mbit mode – a challenge for small field devices. Industrial Ethernet Technologies Page 101 © EtherCAT Technology Group, August 2011 Ethernet Powerlink Standardization Group Classification Profinet Ethernet/IP CC-Link IE Sercos III Powerlink • EPSG originally hosted by Institute of Embedded Systems, Zurich University Winterthur (Switzerland) • In 2006, EPSG Office moved to marketing agency in Aachen, Germany • In 2007, EPSG Office moved to advertising agency in Berlin, Germany • 2007: New Logo and CI • Recent Membership 74 Development: from 72 69 members in 5/2006 to 70 71 members in 11/2006 to 68 71 members in 4/2007 to 66 EPSG 65 members in 11/2007* 64 Modbus/TCP 62 Membership Development 60 EtherCAT Mai 06 Aug 06 Nov 06 Feb 07 Mai 07 Aug 07 Nov 07 Summary * Source: Powerlink Facts May/Nov 2006/April/Nov 2007, published by EPSG; EPSG website © EtherCAT Technology Group Industrial Ethernet Technologies Ethernet Powerlink Standardization Group is managed and hosted by an advertising agency. Technical and implementation support is available by the advertising agency and by technology providers, who charge for these services. Obviously membership figures of EPSG and ETG cannot be compared directly: EPSG charges between 500€ and 5000€ per annum for membership, whilst ETG has adopted the philosophy that charging for access to a technology is not a sign of openness. Therefore in small print: (Between 5/2006 and 11/2007, ETG grew from 315 to 634 members, exceeding 1750 members in Aug 2011). The figures discussed above were taken from the EPSG publication “Powerlink Facts”, which is available for download from the EPSG website. Until end of 2007, there all members were listed; the June 2008 and all later editions do not list members any more. According to EPSG website, one company (Yacoub Automation) joined EPSG in Nov 2007, another one (Kalycito) in April 2008, Yaskawa joined in July 2009 and Xilinx in Oct 2010. The website does not list those companies that have left EPSG since 2007, such as e.g. Wago. Please note that EPSG typically uses the term “members, supporters and users” when referring to membership levels, and accumulates those to over 400* (as of 5/2007). As of 01/2011, the website lists 144 “members and users”. * The EPSG website e.g. lists Tetra Pak in the members and users list. According to a Tetra Pak R&D manager, they used Powerlink in one R&D project which was later cancelled, never delivered a Powerlink equipped system and also terminated their EPSG membership. Industrial Ethernet Technologies Page 102 © EtherCAT Technology Group, August 2011 Future of EPSG? Classification Profinet Ethernet/IP CC-Link IE Sercos III Powerlink Future beyond B&R looks uncertain: • Lenze, driving force behind Powerlink V2, moved to EtherCAT as main system bus • Hardly any new Powerlink products since 2007 • HMS Anybus, supplier of fieldbus interface modules (HMS website: “Anybus products support all major Fieldbus and Ethernet networks“) discontinued their support of Powerlink • Wago, supplier of Powerlink I/O modules, decided to – discontinue its Powerlink products and – quit Ethernet Powerlink Standardization Group Powerlink Modbus/TCP EtherCAT Summary © EtherCAT Technology Group Industrial Ethernet Technologies The Wago Powerlink Bus Coupler was featured in the “product news” section of the “Powerlink Facts” brochure 1/2006 (May 2006), 2/2006 (Nov 2006) and 1/2007 (April 2007). For most of the few new Powerlink Products introduced since 2007, B&R either implemented the Powerlink interface or paid for the implementation. At SPS/IPC/Drives Show in November 2009, B&R introduced EtherCAT products. Industrial Ethernet Technologies Page 103 © EtherCAT Technology Group, August 2011 Powerlink Safety: History Classification Profinet Ethernet/IP CC-Link IE Sercos III Powerlink Modbus/TCP EtherCAT • Development of Powerlink Safety was started in 2003 • In 2004 EPSG denied to make available the Powerlink Safety Protocol for other Ethernet Technologies • Availability of Powerlink Safety Products was announced in 2007 • First Certified Powerlink Safety Products by B&R in 2009 • IXXAT/B&R publish BSD-licensed Powerlink Safety stack in 2009 – As of 6/2010, documentation available in German, only – IXXAT offers technical support within the scope of an extra charged maintenance contract • In April 2010, EPSG turns Powerlink Safety into “openSAFETY”, claiming it to be “The first open and bus-independent safety standard for all Industrial Ethernet solutions”. Summary © EtherCAT Technology Group Industrial Ethernet Technologies • In 2004 IAONA asked EPSG to make available Powerlink Safety for other Ethernet Technologies; this was turned down by EPSG. • Also in 2004, innotec GmbH (a German Safety Consultancy company) filed several patents regarding Powerlink Safety / openSAFETY. These were granted in 2006. • If the BSD-licensed safety stack is modified, the certification has to be started from scratch. Industrial Ethernet Technologies Page 104 © EtherCAT Technology Group, August 2011 Powerlink Safety / openSAFETY Classification Profinet Ethernet/IP CC-Link IE Sercos III Powerlink Modbus/TCP EtherCAT • Announcement of Powerlink Safety (openSAFETY) as Safety Protocol for Ethernet/IP and SERCOS-III takes ODVA and Sercos International by surprise: – Neither Sercos International nor ODVA have authorised the use of their intellectual property in conjunction with openSafety • According to the Powerlink Safety Standard*, – the permissible payload data range is 9–25 Bytes – and 9 Bytes payload data require a minimum Safety Container of 31 Bytes • Or, in other words, communicating a single safety bit (such as the input of a safety light curtain) requires a 31 (!) Byte Protocol to be sent and processed • The resulting limitations are obvious: Powerlink Safety needs bandwidth, requires substantial processing power and cannot be transferred over classical fieldbus systems such as CAN Summary * IEC 61784-3-13, A3.2 “Constraints” © EtherCAT Technology Group Industrial Ethernet Technologies Statement# of Katherine Voss, Executive Director ODVA: “ODVA and Sercos International are cooperating on the adaptation of CIP Safety to their respective industrial Ethernet networks, EtherNet/IP and Sercos III. At this time, ODVA does not have a similar cooperation arrangement with any other organization. … CIP Safety on EtherNet/IP is the only network configuration for functional safety that is authorized by ODVA to run on EtherNet/IP. “ Statement# of Peter Lutz, Managing Director Sercos International: “We were surprised by the unauthorized usage of our registered Sercos trademark in publications and displays on the Ethernet Powerlink Standardization Group (EPSG) booth at Hannover fair. This might imply that the announced concept and the combination of "openSafety" (Powerlink Safety) and Sercos III is approved and supported by Sercos International. We would like to clearly state that no discussions have been held and that no formal agreements are in place between SERCOS International (SI) and either EPSG or B&R. … The introduction of an additional – incompatible – safety protocol is not helpful as the complexity for manufacturers and users is significantly increased and the acceptance is diminished to the same degree.” In Nov 2010, EPSG announced an openSAFETY solution for Profinet. Powerlink Safety, as do most safety protocols, uses the “black channel approach”, which means that the transporting communication channel does not have to be included in the safety considerations. The “black channel approach” is the pre-requisite for bus independence of the safety technology. However, with Powerlink Safety the black channel approach is only valid within the constraints listed above which lead to a minimum safety container of 31 Bytes. For comparison: the minimum safety container of Safety over EtherCAT (FSoE) is 6 bytes (for 1 Byte payload), thus FSoE is suitable e.g. for CAN as well. # Statements quoted from: Industrial Ethernet Book Issue 58 Industrial Ethernet Technologies Page 105 © EtherCAT Technology Group, August 2011 Powerlink Safety / openSAFETY I IOOIIOIOOIOIOOOI IOOIIOIOIOOIIOIO OIOIIOOOIOIOOIOI OOIOIIIOOOIOIOOI OOOOIIIIOIOIIIOO IOOIOOIIIIOOIIOI IIIIIOOIIIOIIIIO OOIIOOIIIOOIOOIO OIOIOIOOIOIOOOIO OIIOIOIOIOOOIOII IOOOOIOOIIIOIOIO OIOIOIOOIOIOIOOO IOIOIOIOIOIIIOIO IIOOOOIOOOOOOIOO OOOIOIOOIOIIOIOI IOIOIOIO OOIIOOIIIOOIOOIO OIOIOIOOIOIOOOIO OIIOIOIOIOOOIOII Safety Input Safety Input in minimum openSAFETY container Safety Input in minimum Safety over EtherCAT container Classification Profinet Ethernet/IP CC-Link IE Sercos III Powerlink Modbus/TCP EtherCAT Summary © EtherCAT Technology Group Industrial Ethernet Technologies A Safety Input device often has only a few Bit of SafeData. For a safe light curtain for example only 1 Bit SafeData can be sufficient. Container length for 1 Bit SafeData Powerlink Safety: 31 Bytes Safety over EtherCAT: 6 Byte Industrial Ethernet Technologies Page 106 © EtherCAT Technology Group, August 2011 Powerlink Safety / openSAFETY Classification Profinet Ethernet/IP CC-Link IE Sercos III Powerlink Modbus/TCP EtherCAT Summary • In “Powerlink Facts” 01/10 EPSG compares openSAFETY with Safety over EtherCAT and concludes that openSAFETY is 4 x faster. This comparison is misleading, since • In most safety architectures the safe PLC is not bypassed (as shown in the openSAFETY example) • If such an architecture is chosen, the network management configuration effort and the resulting traffic is enormous, since the actuators and the safe PLC have to independently monitor all safety communication links with cyclic frames • The safety stack performance (31 byte minimum container size!) is not taken into account • EtherCAT cycles are much faster than Powerlink cycles • Last but not least: decentralized safe PLC is optional © EtherCAT Technology Group Industrial Ethernet Technologies Time synchronization in Powerlink Safety: In order to avoid a delay of data the Consumer must query all connected Producer for their relative time. That means each Producer/Consumer connection needs a bidirectional communication channel on the underlying fieldbus to synchronize the time information. Configuration effort: Within a Producer/Consumer network such as Powerlink the number of communication relations is a multiplication of the number of Producer (n) and the number of Consumer (m). In a Master/Slave network such as EtherCAT the number is a summation. Example: 10 Emergency stop buttons acting on 10 drives Powerlink Safety 10 * 10 = 100 communication relations Safety over EtherCAT 10 + 10 = 20 communication relations Complexity of each device: For Powerlink Safety each Consumer device (e.g. Safety related Drive) must provide several safe connections if it supports several Producer Inputs. The Input information must be combined within the device (Safe Logic functionality). With Safety over EtherCAT a single connection per FSoE Slave device to the FSoE Master is sufficient. The logical combination of Safety Inputs is done in the FSoE Master device. Industrial Ethernet Technologies Page 107 © EtherCAT Technology Group, August 2011 Powerlink Summary Classification Profinet Ethernet/IP CC-Link IE • • • • Polling over Ethernet All Frames are broadcasted Cycle times similar to SERCOS-II Performance difficult to predict: depends on selected devices and on topology. • Requires protected network segment • Requires substantial processing power (master + slave) or implementation in hardware (e.g. FPGA) Sercos III Powerlink Modbus/TCP EtherCAT Summary • V2: Based on (outdated) half duplex Hub technology • Limited no. of nodes can be connected in line topology • Requires Master with dedicated Communication processor: no Commercially of the Shelf (COTS) Network interface card (NIC) • Versions are not downwards compatible • Powerlink V3 announced, but no visible activities any more © EtherCAT Technology Group Industrial Ethernet Technologies Due to the polling principle, the master has to wait for the response of each slave before he can send the next request – or has to wait for the timeout. The response time of each slave device depends • on its individual implementation: - if implemented with standard components: processor performance, software stack implementation quality, varying local CPU load due to application etc. - or: implemented with FPGAs • and on the topology (number and performance of the hubs in between). Thus it is difficult to determine the performance of the network without measuring it. Performance limitations require complex bandwidth optimization in more demanding applications. Industrial Ethernet Technologies Page 108 © EtherCAT Technology Group, August 2011 Modbus/TCP: Overview Classification Profinet Ethernet/IP CC-Link IE Sercos III Powerlink • Schneider Electric Approach: serial Modbus on TCP/IP • Follows Approach A • Few Services, simple to Request from Master Ethernet Header implement Ethernet Header IP Header IP Header TCP Header • Widely used TCP Header Transaction ID Transaction ID Protocol ID • Many Products Protocol ID Length available Length Unit ID Unit ID • Non-Real-Time Modbus fct code Modbus fct code Approach. A Data Data Modbus/TCP Response from Slave EtherCAT Summary © EtherCAT Technology Group Modbus/TCP is very widely used, since it is simple to implement. Non-real-time approach: Due to its operating principle, Modbus/TCP cannot guarantee delivery times or cycle times or provide precise synchronization. Strongly depending on the stack implementation, response times of a few milliseconds can be achieved, which may be sufficient for certain applications. Apart from the basic data exchange mechanisms, there is hardly any additional feature. Network management, device profiles, etc. have to be handled by the application program, the network layer does not provide solutions. Industrial Ethernet Technologies Page 109 © EtherCAT Technology Group, August 2011 Modbus/TCP: Functional Principle Classification Profinet Ethernet/IP CC-Link IE Sercos III Powerlink • Polling • Each Request/Response Cycle passes TCP/IP Stack 4 Times • plus Switch Delays • Depending on Master, Poll Request can be issued before the corresponding response has returned. Master Slave Modbus 1 TCP IP Modbus 4 2 TCP IP 3 1 2 Slave 5 Modbus/TCP Slave 4 3 EtherCAT Slave Slave Summary © EtherCAT Technology Group Modbus/TCP master implementations can either wait for each response to return before the next request is issued, or send several requests at once in order to allow for parallel processing in the slave devices. In the later case the overall performance is improved. Since the performance is primarily determined by the stack performances, it very much depends on the implementation of the master and slave devices – which is difficult to assess. If a master is implemented on a standard socket interface of a Windows OS, typical response times (per slave) are in the order of 10-20ms with a worst case (e.g. moving a Window) of well over 250ms (We have tested this. The reason is that the OS processes the TCP/IP stack with low priority). Of course it is possible to implement a master with an RTOS and/or using a dedicated communication CPU and achieve better results. A slave device with sufficient processing power and an optimized (=functionally reduced) TCP/IP stack may typically reply within 1-4 ms (and in worst case, depending on the load, within 10-15ms). Standard TCP/IP stacks on µC may have typical response times of >5ms. Critical can be the retry times of the TCP/IP stacks – in case a frame was lost. These retry times can be in the order of seconds – and typically are not user definable nor mentioned in the product manuals. Industrial Ethernet Technologies Page 110 © EtherCAT Technology Group, August 2011 Modbus/TCP: Future? Classification • In April 2007, Schneider Electric joined ODVA as principal member and announced Ethernet/IP products for 2008. Profinet • ODVA announced „to provide compatibility of Modbus®/TCP devices with networks built on CIP” Ethernet/IP CC-Link IE Sercos III • A “Modbus Integration SIG” was established to specify the “CIP to Modbus Translator” • Modbus Translation Services for Modbus TCP devices were added to the CIP Specifications in Nov 2007 Powerlink Modbus/TCP EtherCAT • Future of Modbus/TCP looks uncertain, since driving force seems to walk away Summary © EtherCAT Technology Group Modbus/TCP will certainly not vanish any time soon, but this move of Schneider indicates that there will not be enhancements or maintenance of the protocol. The most recent technical document found on the Modbus website in Aug 2011 is the MODBUS MESSAGING ON TCP/IP IMPLEMENTATION GUIDE V1.0b from October 2006. Schneider replaces one non-real-time protocol by another one. Details regarding the integration of Modbus TCP into CIP can be found here: http://www.modbus.org/docs/CIP%20Modbus%20Integration%20Hanover%20Fair_0408.pdf Industrial Ethernet Technologies Page 111 © EtherCAT Technology Group, August 2011 EtherCAT Overview Classification Profinet Ethernet/IP CC-Link IE Sercos III Powerlink Modbus/TCP C • EtherCAT is: – Industrial Ethernet down to the I/O Level – Flexible Wiring and simple Configuration – lower cost – well proven – an open technology • Key Principle: Frame Processing on the Fly • Master uses Standard Ethernet Controllers A EtherCAT Ethernet HDR FH EH Data WC CRC Summary © EtherCAT Technology Group Industrial Ethernet Technologies The Slave implementation of EtherCAT is a class C approach: the „processing on the fly“ technology requires dedicated slave controllers. The slave controllers can be implemented as FPGA or ASIC – both solutions undercut the cost levels of the other technologies discussed in this presentation. It is not required to buy an ASIC, and there will be several sources both for FPGA and ASIC implementations. On the master side, EtherCAT does not require a dedicated master card: any standard Ethernet Controller is sufficient, the master functionality is implemented in software running on the host CPU that also runs the application program. It was found that the master code adds less load on the host CPU than servicing the DPRAM of an intelligent plug in card. Industrial Ethernet Technologies Page 112 © EtherCAT Technology Group, August 2011 EtherCAT: Ethernet “on the Fly“ Classification Minimal protocol overhead via implicit addressing Profinet IPC Ethernet/IP .. .. DVI Sercos III Powerlink Modbus/TCP EtherCAT Summary Data WKC EH Data WKC EH Data WKC Ethernet HDR FH EH CC-Link IE CRC • Optimized telegram structure for decentralized I/O • Communication completely in hardware: maximum performance • no switches needed if only EtherCAT devices in the network • Outstanding diagnostic features • Ethernet-compatibility maintained © EtherCAT Technology Group Industrial Ethernet Technologies EtherCAT is very effective even with small amounts of data per slave device, since it is not necessary to send an individual Ethernet frame for each data unit. Since process data communication is handled completely in hardware (EtherCAT Slave Controller), the network performance does not depend on the µC performance of the slave devices – and is thus predictable. This is not necessarily the case with Profinet, Ethernet/IP, Modbus/TCP and Powerlink. Switches are optional. Thus there are no costs related to switches, their power supply, mounting, wiring, configuration and so on. Since the CRC is checked by each device - regardless if the frame is intended for this node – bit errors are not only detected immediately, but can be also located exactly by checking the error counters. The EtherCAT approach is still Ethernet compatible: in the master commercially off the shelf Ethernet MACs are sufficient, since only standard Ethernet frames are used. Industrial Ethernet Technologies Page 113 © EtherCAT Technology Group, August 2011 EtherCAT Performance Example Classification Profinet Ethernet/IP CC-Link IE • • • • 40 Axis (each 20 Byte Input- and Output-Data) 50 I/O Station with a total of 560 EtherCAT Bus Terminals 2000 Digital + 200 Analog I/O, Bus Length 500 m Performance EtherCAT: Cycle Time 276µs at 44% Bus Load, Telegram Length 122µs • For comparison: Sercos III 479 µs, Profinet IRT 763 µs, Powerlink V2 2347µs, Profinet RT 6355 µs in spite of this cycle time still 56% bandwidth remaining, e.g. for TCP/IP Sercos III Powerlink Modbus/TCP EtherCAT Summary © EtherCAT Technology Group Industrial Ethernet Technologies The cycle time figures of the competing technologies were determined as follows: Profinet: Computations based on the specification (done by a well known Profinet expert). The configurable cycle time for this example would be 1ms (IRT) resp. 8ms (RT). Powerlink: see Powerlink section of this presentation. With Powerlink at this cycle time there is no remaining bandwidth for asynchronous communication. For EtherCAT the Update Time (276 µs) is given: after this period of time all output data and all input data was transferred from or to the master – an entire cycle was finished. The telegram time is only 122µs – thus one could communicate even faster (e.g. new data every 125µs). Industrial Ethernet Technologies Page 114 © EtherCAT Technology Group, August 2011 EtherCAT Synchronization Classification Profinet Ethernet/IP Precise Synchronization (<< 1 µs!) by exact adjustment of distributed clocks. Advantage: Accuracy does not depend on master precision, small communication jitter and thus implementation in software only is acceptable and does not deteriorate synchronization S M CC-Link IE ∆t IP C Sercos III S .. .. S DVI Powerlink Modbus/TCP S S S S S EtherCAT Summary © EtherCAT Technology Group Industrial Ethernet Technologies Since EtherCAT used precisely adjusted distributed clocks (a feature of the EtherCAT Slave Controller chips), the communication cycle itself does not have to be absolutely equidistant – a small jitter is allowed. Therefore EtherCAT masters do not need a special hardware (like a communication co-processor) and can be implemented in software, only – all that is needed is an Ethernet MAC, like the one that comes with most PC motherboards anyhow. Measurements showed a synchronization accuracy of ~20ns with 300 distributed nodes and 120m (350 ft) cable length. Since the maximum jitter depends on many boundary conditions (e.g. no. of nodes, network length, temperature changes etc.), its value is given conservatively with << 1µs. Industrial Ethernet Technologies Page 115 © EtherCAT Technology Group, August 2011 EtherCAT is Industrial Ethernet Classification Profinet Ethernet/IP CC-Link IE Sercos III Powerlink Modbus/TCP • • • • EtherCAT: only Standard Ethernet Frames (IEEE 802.3) Master: Ethernet MAC without co-processor or special HW Fully transparent for other Ethernet protocols Internet Technologies (TCP/IP, FTP, Web server etc.) without restricting the real time capabilities, even with 100µs cycle time – no large time gaps for rare traffic needed • Full Tool-Access to devices at real time operation – with and without TCP/IP 48 Bit 48 Bit 16 Bit 16 Bit Destination Source EtherType Header Embedded in Standard Ethernet Frame, EtherType 0x88A4 EtherCAT 11 Bit Summary © EtherCAT Technology Group CRC 1..n EtherCAT Datagrams Length 0 32 Bit … 1 Bit 4 Bit Res. 11 Type 12 15 Industrial Ethernet Technologies EtherCAT used only standard frames. Any other Ethernet Protocols are tunneled fully transparently – EtherCAT thus uses a method that is common with Ethernet itself and with many Internet technologies: every modem tunnels Ethernet frames as does WLAN. VPN uses this approach as does TCP/IP itself. By using this approach EtherCAT can transport any Ethernet protocol (not ony TCP/IP) at shortest cycle times (even if they are shorter than the longest possible Ethernet frame). In addition, it is not necessary to keep a large gap in the data stream – like other approaches have to. The protocol used is named “Ethernet over EtherCAT”. Many EtherCAT masters support tool access from outside: a tool can communicate via Ethernet e.g. by UDP/IP with the master, who inserts this data into the EtherCAT communication in such a way, that a fully transparent access to EtherCAT devices is possible without restricting the real time capabilities. Industrial Ethernet Technologies Page 116 © EtherCAT Technology Group, August 2011 EtherCAT is Industrial Ethernet Classification Profinet Ethernet/IP • Connection to any Ethernet device via Switchport • Access to web server with standard browser • Switchport can be implemented as device feature, seperate device or software functionality in master • Switchport allows for hard real time capability with parallel Ethernet communication of any kind CC-Link IE Sercos III IP C Powerlink Modbus/TCP .. .. DVI Switchport EtherCAT Summary © EtherCAT Technology Group Industrial Ethernet Technologies The “tunnel entrance” (Switchport) for any Ethernet protocol can be implemented in a variety of ways: as separate device, as feature of a slave device or as software feature of the EtherCAT master. Industrial Ethernet Technologies Page 117 © EtherCAT Technology Group, August 2011 EtherCAT: Most flexible Topology Classification Profinet Ethernet/IP • • • • • Flexible tree structures – arbitrarily extendable Line without limitations through cascaded switches or hubs 100 m between two nodes, up to 65535 nodes in one segment branches can be connected/removed at run time (“Hot Connect”) Straight or crossed cables – automatic detection CC-Link IE Sercos III I P C .. DVI Powerlink Modbus/TCP EtherCAT Summary © EtherCAT Technology Group Industrial Ethernet Technologies With EtherCAT almost any number of devices (up to 65535) can be wired in a line structure – there are no restrictions due to cascaded switches or hubs. Any number of drop lines or branches are possible, too, providing the most flexible topology. Industrial Ethernet Technologies Page 118 © EtherCAT Technology Group, August 2011 EtherCAT Gateways Classification Profinet Ethernet/IP • • • • • EtherCAT Performance allows for: EtherCAT instead of PCI no card slots required any more maximum system expandability with low cost fieldbus gateways seamless integration of fieldbus devices protects your investment smooth migration path from fieldbus to EtherCAT CC-Link IE Sercos III Powerlink Modbus/TCP EtherCAT Summary © EtherCAT Technology Group Industrial Ethernet Technologies EtherCAT is so fast that it can replace the PCI bus (and thus the PCI slots) in almost all applications. Fieldbus master and slave card can be moved into the EtherCAT network. EtherCAT control computers can thus be very compact, without restricting the expandability. In addition, this feature provides a very elegant and smooth migration path: Devices which are not (yet) available with EtherCAT interface, can be integrated via underlying fieldbus systems – typically without restricting the performance compared with the PCI solution. Industrial Ethernet Technologies Page 119 © EtherCAT Technology Group, August 2011 Safety over EtherCAT: Features Classification • TÜV certified technology Profinet • Developed according to IEC 61508 Ethernet/IP • Protocol meets Safety Integrated Level (SIL) 4 • Device implementations typically SIL 3 CC-Link IE Sercos III Powerlink • Suitable for functional safe I/O as well as for functional safe motion control • Variable CRC size for minimal overhead Modbus/TCP • Safe Parameter Download at boot-up: most simple device exchange possible EtherCAT • Safety devices available since end of 2005 Summary © EtherCAT Technology Group Industrial Ethernet Technologies The error probability of the Safety over EtherCAT protocol is low enough, that the protocol itself meets SIL 4 requirements. However, devices implementing this protocol typically meet SIL 3 – and thus KAT 4 of EN 954-1. Industrial Ethernet Technologies Page 120 © EtherCAT Technology Group, August 2011 Safety over EtherCAT: Technology Approach Classification Profinet Standard application Ethernet/IP CC-Link IE Sercos III Powerlink Safety application Safety application Safety protocol EtherCAT protocol Standard application Safety Protocol EtherCAT protocol Safety over EtherCAT EtherCAT Modbus/TCP EtherCAT EtherCAT acts as a real ‚black channel‘ Summary © EtherCAT Technology Group Industrial Ethernet Technologies With Safety over EtherCAT the communication channel is really “black” (or irrelevant for the safety analysis), and not “grey”. Therefore e.g. no SIL monitor is required to check the current error rate on the network. Industrial Ethernet Technologies Page 121 © EtherCAT Technology Group, August 2011 Without Redundancy: Cable Failure Master Classification Profinet RX Unit TX Unit RX TX Ethernet/IP MAC 1 RX TX CC-Link IE Sercos III Powerlink Modbus/TCP EtherCAT Summary ☺ ☺ Slave 1 Slave M-1 Slave M+1 RX TX RX TX TX RX TX RX RX TX TX RX ... © EtherCAT Technology Group Slave N ... RX TX TX RX Industrial Ethernet Technologies EtherCAT is – even when wired in line topology – a ring structure, with two channels in one cable (Ethernet full duplex feature). Whilst device located before a cable or device failure can continue to operate (the EtherCAT Slave Controller closes the ring automatically), devices behind the cable failure are naturally not accessible any more. Industrial Ethernet Technologies Page 122 © EtherCAT Technology Group, August 2011 With Redundancy: Cable Failure Master Classification Profinet Ethernet/IP Reco 5µs! e: < 1 m i T very CC-Link IE RX Unit TX Unit RX TX MAC 1 RX TX MAC 2 RX TX Only 2nd Ethernet Port required – no special Interface Card Sercos III Powerlink Modbus/TCP EtherCAT Summary ☺ ☺ ☺ ☺ Slave 1 Slave M-1 Slave M+1 Slave N RX TX RX TX TX RX TX RX RX TX TX RX ... © EtherCAT Technology Group ... RX TX TX RX Industrial Ethernet Technologies If the line is turned into a ring, there are two communication paths to each device: redundancy. With EtherCAT even without special hardware in the master: a second Ethernet port is sufficient. All slave device with two (or more) EtherCAT ports support the cable redundancy feature anyhow. The recovery time in case of cable failure is shorter than 15µs. The initial switchover to the redundant line does not require any reconfiguration by the master. By using this device exchange at run time (hot swap) is feasible as well. Industrial Ethernet Technologies Page 123 © EtherCAT Technology Group, August 2011 EtherCAT is simpler to configure Classification Addressing: • No manual address setting required Profinet • Addresses can be kept – no new addressing if nodes are added Ethernet/IP Topology: • Automatic topology target/actual comparison possible CC-Link IE Sercos III Diagnosis: • Diagnosis information with exact localization Network planning: Powerlink • Performance independent of slave implementation (e.g. stack features, µC performance) Modbus/TCP • Performance widely independent from topology (no switches/hubs) EtherCAT • Performance more than sufficient - therefore no „tuning“ required any more, default settings do the job Summary © EtherCAT Technology Group Industrial Ethernet Technologies The configuration of an EtherCAT network is very simple. This is in particular the case for the network planning: since the process data performance does not depend on the devices that were selected (and their µC and stack performance) and since the topology has almost no influence at all, hardly anything has to be considered. Also the network tuning, which has been necessary with many fieldbus and industrial Ethernet solutions, is hardly needed at all: even with default settings Ethernet is more than fast enough. Industrial Ethernet Technologies Page 124 © EtherCAT Technology Group, August 2011 EtherCAT Implementation Classification Beckhoff ® ET1100 Profinet Hilscher Ethernet/IP netX® 100/500 TI's Sitara™ and other µC + µP families Hilscher netX® 50 Beckhoff ® ET1200 CC-Link IE Sercos III 2005 Powerlink 4 0 20 Modbus/TCP EtherCAT ESC10/20: Altera® Cyclone™-I 2006 2007 IP-Core Xilinx® Spartan™-3 IP-Core for Altera® Cyclone™-II 2008 2009 2011 2010 2012 IP-Core for FPGA of Intel® Atom™ E6x5C IP-Core for IP-Core for Xilinx® Altera® Spartan™-6 Stratix™-IV IP-Core for Altera® Cyclone™-III IP-Core for Altera® Cyclone™-IV IP-Core for Xilinx® Kintex™-7 IP-Core for Altera® Stratix™-V Summary © EtherCAT Technology Group Industrial Ethernet Technologies At Hannover Fair 2011, Texas Instruments announced the EtherCAT Slave Controller integration in its ARM® -based embedded processors. This is the first time ever that a dedicated Industrial Ethernet hardware interface is integrated in standard microprocessor product lines. The TI chip turns EtherCAT into a mainstream technology also beyond the automation world, will help EtherCAT to establish a strong position in a wide range of embedded applications and further accelerate the adoption of EtherCAT in the automation market, Like all Industrial Ethernet technologies that support hard real time, EtherCAT requires a dedicated hardware interface – unlike its competition EtherCAT requires such hardware only on the slave side. This provides both maximum and predictable performance of the network, since software stack delays do not have any influence any more. In addition this leads to lower costs. The first EtherCAT Slave Controller (ESC) back in 2004 was FPGA based, released by the originator of the technology, the German company Beckhoff Automation. In 2005 – 2007 EtherCAT ASICs were introduced by Beckhoff and Hilscher. Many EtherCAT device vendors also make use of the configurable EtherCAT IP-Cores for Altera and Xilinx FPGAs. The Texas Instruments microcontroller and microprocessor families will complement the offering of EtherCAT chips by the end of 2011. Industrial Ethernet Technologies Page 125 © EtherCAT Technology Group, August 2011 EtherCAT is lower costs Classification Profinet Ethernet/IP Master: no dedicated plug in card (co-processor), on-board Ethernet Port is fine CC-Link IE Sercos III Powerlink Modbus/TCP EtherCAT Slave: - low cost Slave Controller - FPGA or ASIC - no powerful µC needed Infrastructure: - no Switches/Hubs required - Standard Ethernet Cabling Summary © EtherCAT Technology Group Industrial Ethernet Technologies EtherCAT intends to even undercut the fieldbus cost levels – in spite of a performance, that is much better and many additional features. Industrial Ethernet Technologies Page 126 © EtherCAT Technology Group, August 2011 EtherCAT: open technology Classification Profinet Ethernet/IP CC-Link IE Sercos III Powerlink Modbus/TCP EtherCAT Summary • Protocol is published completely: • EtherCAT is IEC standard (IEC 61158, IEC 61784-2, IEC 61800-7, ISO standard (ISO 15745-4) and SEMI standard (E54.20) • Slave Controllers from several suppliers • Master Stacks from several suppliers (also open source) • Supported by the EtherCAT Technology Group • Foundation: November 2003 • Tasks: Support, Advancement and Promotion of EtherCAT • Already more than1750* member companies from 52 countries in 6 Continents: –Device Manufacturers –End Users –Technology-Provider • ETG Offices in Germany, USA, China, Japan and Korea • Membership is open to everybody * as of Aug 2011 © EtherCAT Technology Group Industrial Ethernet Technologies The EtherCAT Technology Group is official standardization partner of the IEC: the ETG nominates experts for the international standardization committees and may submit standard proposals. Since beginning of 2005 EtherCAT is an official IEC specification: IEC/PAS 62407. Since Oct. 2007 EtherCAT is part of the standards IEC 61158 (Digital data communication for measurement and control – Fieldbus for use in industrial control systems), IEC 61784-2 (Digital data communication for measurement and control –Part 2: Additional profiles for ISO/IEC 8802-3-based communication networks in real-time applications) and IEC 61800-7 (Profiles for motion control systems). The latter is particularly important for motion control applications, since it makes EtherCAT a standardized communication technology for the SERCOS and CANopen drive profiles, on an equal footing with SERCOS I-III and CANopen respectively. The drive parameters and state machines as well as the process data layout of the device profiles remain untouched when mapped to EtherCAT. Hence the user interface does not change when moving from SERCOS and CANopen to EtherCAT, and device manufacturers can re-use major parts of their firmware. EtherCAT is also part of ISO 15745-4 (device description profiles) The EtherCAT Technology Group (ETG) is an organization in which key user companies from various industries and leading automation suppliers join forces to support, promote and advance the EtherCAT technology. With over 1750 members, the EtherCAT Technology Group has become the largest fieldbus organization in the world. Founded in November 2003, it is also the fastest growing fieldbus organization. Industrial Ethernet Technologies Page 127 © EtherCAT Technology Group, August 2011 EtherCAT: versatile System Classification Profinet Ethernet/IP CC-Link IE • Master to Slave, Slave to Slave, Master to Master • Transparent tool access to all nodes • open interfaces Master M/S IPC M/S Sercos III Switch .. .. DVI M/M Powerlink Master IPC Modbus/TCP EtherCAT M/S .. .. DVI S/S Summary © EtherCAT Technology Group Industrial Ethernet Technologies Besides the master/slave communication EtherCAT provides further possibilities: masters can communicate among each other as well as slave devices. For slave to slave communication there are two varieties: Topology dependent slaves can insert data “upstream” which can be read “downstream” by all other slaves. In many applications that require slave to slave communication these relationships are known at network planning stage and thus can be handled with accordingly. Wherever this is not possible, the second variant can be applied: Topology independent two cycles are used for slave to slave communication. In most cases the corresponding delay time is not critical at all – in particular if one considers that EtherCAT is even at twice the cycle time still faster than any other solution…. Industrial Ethernet Technologies Page 128 © EtherCAT Technology Group, August 2011 EtherCAT also for Factory Networking Classification Profinet Ethernet/IP CC-Link IE Sercos III Powerlink Modbus/TCP EtherCAT Summary © EtherCAT Technology Group Industrial Ethernet Technologies The EtherCAT protocol portfolio was enhanced by the EtherCAT Automation Protocol (EAP). As a result, EtherCAT now also comprises the Ethernet communication between control systems, as well as to the supervisory systems. EAP simplifies the direct access of process data from field devices at the sensor / actuator level and also supports the integration of wireless devices. For the factory level, the base protocols for process data communication have been part of the EtherCAT specification from the very beginning. Now the ETG has enhanced those with services for the parameter communication between control systems and for routing across system boundaries. Uniform diagnostic and configuration interfaces are also part of the EAP. It can be used in switch-based Ethernet topologies as well as via wireless Ethernet. Process data is communicated like network variables, either cyclically or event-driven. Both the classic EtherCAT Device Protocol, which utilizes the special EtherCAT functional principle of "processing on the fly," and the new EAP make use of the same data structures and facilitate vertical integration to supervisory control systems and networked controllers. While EAP handles the communication in the millisecond range on the process control level and between control systems, the EtherCAT Device Protocol handles I/O and motion control communication in the field level in the microsecond range. Industrial Ethernet Technologies Page 129 © EtherCAT Technology Group, August 2011 EtherCAT Performance Classification EtherCAT is the fastest Industrial Ethernet Technology: Profinet Transmission Rate: 2 x 100 Mbaud (Voll-Duplex) Ethernet/IP Update Times: • 256 digital I/O in 11 µs • 1000 digital I/O distributed to 100 nodes in 30 µs = 0.03 ms • 200 analog I/O (16 bit) in 50 µs, 20 kHz Sampling Rate • 100 Servo-Axis (each 8 Byte I+O) every 100 µs = 0.1 ms • 12000 digital I/O in 350 µs CC-Link IE Sercos III Powerlink Modbus/TCP EtherCAT More details ? ….. see EtherCAT Presentation or EtherCAT website www.ethercat.org Summary © EtherCAT Technology Group Industrial Ethernet Technologies The performance figures have been determined with a mix of physical layers, thus representing typical installations. A comprehensive EtherCAT introduction can be found at the EtherCAT website. Industrial Ethernet Technologies Page 130 © EtherCAT Technology Group, August 2011 EtherCAT Summary Classification Profinet Ethernet/IP CC-Link IE Sercos III Powerlink Modbus/TCP EtherCAT • EtherCAT provides: – Superior Performance – Line, Ring, Tree, Drop Line, Star Topology – Master/Slave, Master/Master and Slave/Slave communication – Integrated Functional Safety: Safety over EtherCAT – TCP/IP without cycle time limitations – Simple configuration – no manual address setting – Comprehensive diagnosis functionality – Redundancy – Support of CANopen* and SERCOS* Drive Profiles • EtherCAT is: – Open technology, worldwide supported, IEC standard – Low cost and simple to implement Summary *CANopen is a trademark of CiA e.V.; SERCOS interface™ is a trademark of SI e.V. © EtherCAT Technology Group Industrial Ethernet Technologies EtherCAT typically is chosen for one or more of these three reasons: - superior performance - flexible topology – even at large distances - low costs For more information regarding EtherCAT please go to www.ethercat.org Industrial Ethernet Technologies Page 131 © EtherCAT Technology Group, August 2011 Stack Performance Comparison (I) Classification Profinet Ethernet/IP • Stack performances of the Ethernet technologies differ substantially, due to the different complexity of the stacks • Softing, a German specialist for field bus technology published* the following comparison of the stack delay times: CC-Link IE Sercos III Powerlink Modbus/TCP EtherCAT Stack Time Profinet IO Ethernet/IP EtherCAT Average 0.5788 ms 1.8873 ms 0.1143 ms Max: 0.7391 ms 2.9571 ms 0.1821 ms Min: 0.5394 ms 1.2332 ms 0.0474 ms • All three protocols were implemented on the same hardware (interface board with FPGA + Softcore CPU) and by the same team, so they are indeed comparable * Source: „Einer für alle; Flexible Real-Time-Ethernet Anschaltung mit FPGA“, messtec drives Automation Real-Time Ethernet Sonderheft 2010, by Frank Iwanitz, Business Development Manager Real-Time Ethernet at Softing GmbH, Munich, Germany Summary © EtherCAT Technology Group • • • • Industrial Ethernet Technologies Most performance comparisons only look at the network itself up to the slave controller chips, and neglect the stack performances. However, the stack performance is crucial when looking at the overall network system performance Softing is using the eCos RTOS on the Softcore CPU that runs the stacks The stack times were measured from the interrupt that is generated at the reception of the Ethernet frame at the IP core until the data is made available to the application at the application interface (stack API). Industrial Ethernet Technologies Page 132 © EtherCAT Technology Group, August 2011 Stack Performance Comparison (II) Classification • Softing stack performance data shown in a diagram, + Beckhoff EtherCAT Slave Sample Code (SSC*) Profinet Ethernet/IP CC-Link IE Sercos III Powerlink Modbus/TCP EtherCAT * SSC Stack Delay time measured on EL9800 EtherCAT Evaluation Kit using the 10 Mhz Serial Process Data Interface and a 40 MHz 16 Bit PIC CPU; 2 Byte Output Data, min 15µs, max 20µs Summary © EtherCAT Technology Group • • Industrial Ethernet Technologies Most performance comparisons only look at the network itself up to the slave controller chips, and neglect the stack performances. However, the stack performance is crucial when looking at the overall network system performance Industrial Ethernet Technologies Page 133 © EtherCAT Technology Group, August 2011 RTE Technology Comparison: Summary Classification Performance Profinet Ethernet/IP Cycle Time Modbus /TCP Ethernet /IP ProfiNet RT Powerlink ProfiNet IRT CC-Link IE Sercos III EtherCAT -- -- - o + o + ++ -- -- -- - + + + ++ + -- - o CC-Link IE Sercos III Synchronicity Powerlink Modbus/TCP Throughput of IP Data + o (CIP sync) (with special interface hw) ++ ++ ++ o (half duplex) EtherCAT Summary © EtherCAT Technology Group Industrial Ethernet Technologies In principle, one should not compare technologies in such an overview table: since the ratings are based on figures, assumptions and assessments that cannot be given in full detail, one may come to a different conclusion. However, some like this and ask for these tables. In order to provide a better transparency, comments for each row are provided. Cycle Time: EtherCAT is about 3 times faster than Profinet IRT and Sercos-III, and about 10-15 times faster than Powerlink or CC-Link IE. Due to TCP/IP usage for process data communication and the related stack delays, the Modbus cycle time in principle is longer than with Profinet I/O – but this is widely implementation dependent. Synchronicity: The EtherCAT distributed clock mechanism provides jitter-values of <<1µs. With Sercos-III, Powerlink and CC-Link IE the jitter depends on the communication jitter of the master, with Profinet-IRT (and Powerlink and CC-Link IE Field) it (also) depends on the number of cascaded switches resp. hubs. All four technologies claim a jitter of <1µs – as does CIPsync. Throughput of IP data: with the „best effort“ approaches Modbus, Ethernet/IP and Profinet RT the throughput of IP data is basically limited by the stack performance. Since Profinet IRT and EtherCAT reserve bandwidth for Real-time communication, the remaining throughput for IP data is reduced by the protocol – but typically it remains higher than the stack performance of an embedded TCP/IP stack. With IRT the user has to ensure that certain load limits are not exceeded. Powerlink suffers from half duplex communication and overall poor bandwidth utilization due to polling. CC-Link IE does not transport other Ethernet traffic (the SLMP option is the other way round: SLMP via TCP/IP in external Ethernet networks). Sercos-III suffers from the delay introduced by large no. of cascaded switches (in Realtime Mode). Industrial Ethernet Technologies Page 134 © EtherCAT Technology Group, August 2011 RTE Technology Comparison: Summary Classification Wiring Profinet Modbus /TCP Ethernet /IP ProfiNet RT Powerlink ProfiNet IRT CC-Link IE Sercos III EtherCAT - ++ -- Ethernet/IP Topology Flexibility CC-Link IE -- -- -- + + (Control) + (Field) Sercos III Line Structure Powerlink -- -- -- o o (10) (~25) -- (Control) + + ++ (511) (65535) - + (Field) COTS Modbus/TCP Infrastructure Components ++ + o o (no Switch) EtherCAT (Switch, Router, Connector etc.) -- -- (Control) + (Field) Summary © EtherCAT Technology Group Industrial Ethernet Technologies Topology Flexibility: EtherCAT supports line, tree, star, ring, drop lines without practical limitations on number of nodes and hardly any influence on performance. Profinet IRT: line, tree, star, drop lines, but limited no. of nodes and strong interdependency between topology and performance. CC-Link IE Control: ring only; CC-Link IE Field: star + line, ring announced. Powerlink: line, tree, star, drop lines, but strong limitation due to hub delays. Sercos-III: line and ring only. Line Structure: ModbusTCP, Ethernet/IP + Profinet RT only support line topology with device integrated switches – and of course, the switch delays accumulate. With Powerlink, only few nodes in line, due to hub delays. According to B&R user manual, a maximum of 10 hubs is allowed between master and slave – so only 10 nodes in line. With Profinet IRT, accumulated jitter due to cascaded switches limits the no. of nodes in line topology. CC-Link IE Field: up to 121 nodes in line, Sercos-III specifies up to 511 nodes in line, EtherCAT supports up to 65535. Commercially Off The Shelf (COTS) Infrastructure Components: Ethernet/IP asks for manageable switches with IGMP support. Hubs with 100 MBit/s (Powerlink) cannot be considered COTS technology, since the chips are obsolete. Profinet RT requires a careful switch selection. Profinet IRT requires special switches throughout, Sercos-III does not allow switches, EtherCAT can be used with switches (between masters and EtherCAT segments). If required, EtherCAT networks can be further extended e.g. by inserting fiber optic segments using standard infrastructure devices. CC-link IE Control: no COTS devices possible; CC-Link IE Field: Switches can be used. Industrial Ethernet Technologies Page 135 © EtherCAT Technology Group, August 2011 RTE Technology Comparison: Summary Classification Features Profinet Ethernet/IP Slave to Slave Communication Modbus /TCP Ethernet /IP ProfiNet RT Powerlink ProfiNet IRT CC-Link IE Sercos III EtherCAT ✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔ -/✔ ✔ ✔ (switches with spanning tree) ✔ ✔ ✔ o* ✔ ✔ ✔ - ✔ ✔ ✔ ✔ - ✔ ✔ CC-Link IE TCP/IP & other Internet Sercos III Technologies supported Powerlink Cable Redundancy Modbus/TCP Safety EtherCAT Summary # * planning algorithm extremely complex, no known implementation # CC-Link Safety is separate bus system, Safety Protocol for CC-Link IE Field announced in July 2011 © EtherCAT Technology Group Industrial Ethernet Technologies Slave to Slave Communication: supported by all technologies. Via Master only: Modbus/TCP. Directly between slaves, but initiated by master: all others (EtherCAT: depending on topology). Topology independent slave-to-slave communication with EtherCAT requires 2 frames (which can be sent within the same cycle), so performance of this communication type may be degraded to Sercos-III or Profinet IRT levels. TCP/IP & other Internet Technologies supported: almost all technologies allow for TCP/IP communication and Internet Technologies. Modbus/TCP, Ethernet/IP and Profinet I/O have no scheduling for this communication, all others do. Powerlink, Profinet-IRT, Sercos-III and EtherCAT connect generic Ethernet devices (e.g. Service notebooks) via Gateways or special switchports. CC-Link IE Field can connect external SLMP/TCP/IP devices via Gateway, but cannot transport generic TCP/IP or Ethernet traffic. Cable Redundancy: For Modbus/TCP switches with spanning tree protocol can be used to establish cable redundancy (between the switches only). Ethernet/IP has introduced the DLR protocol (and the corresponding devices). For Profinet RT there is the Media Redundancy Protocol (MRP). For Powerlink, redundancy requires doubling of all infrastructure components plus additional redundancy interface devices (or special redundancy slaves). Profinet IRT aims for redundancy (MRP is not suitable for IRT), but the planning algorithm for a redundant IRT topology is so complex that its implementation is questionable. Sercos-III and EtherCAT support cabling redundancy, for EtherCAT with very little additional hw effort (only a 2nd Ethernet port in the master, no special card). Safety: There is no Modbus/TCP safety protocol. The safety approaches of the other technologies differ regarding availability: Safety over EtherCAT products are shipping since end of 2005. Industrial Ethernet Technologies Page 136 © EtherCAT Technology Group, August 2011 RTE Technology Comparison: Summary Classification Costs Profinet Modbus /TCP Ethernet /IP ProfiNet RT Ethernet/IP Node Interface Costs CC-Link IE Sercos III Development Effort Powerlink Master Costs Modbus/TCP Infrastructure Costs EtherCAT o - ++ + - + -- (Switch) (Switch) -+ -o (Switch) Powerlink ProfiNet IRT + ERTEC400 CC-Link IE ? (w. FPGA) o ERTEC200 o -* o --* o ? -* o (Hubs integr.) (Switch integr.) (Switch integr.) Sercos III EtherCAT + ++ + (w. FPGA) (w. FPGA) + + -* ++ ++ ++ (no Switch) (no Switch) (Switch integrated) Summary © EtherCAT Technology Group * Requires Special Master Card with Co-Processor Node Costs: Whilst Modbus/TCP – due to limited real time claims – can be implemented on 16bit µC, Ethernet/IP, Profinet I/O and Powerlink require substantial processing power and memory. Using FPGAs, Powerlink, Sercos and EtherCAT achieve comparable cost levels, the ASIC implementation of EtherCAT reaches or undercuts fieldbus cost levels. Node costs for CC-Link IE Field are difficult to determine, since the ASICs are not available (at least not in Europe). CC-Link IE Control ASICs are not available at all. Development effort: Assuming the TCP/IP stack is present, Modbus/TCP can be implemented with very low effort. Profinet I/O requires about 1 MByte (!) of code. Profinet IRT is very complex – not only but in particular the master. EtherCAT slaves can be implemented with very little effort, since all time critical functions are provided in hardware. EtherCAT masters range from very simple (e.g. with one process image) or more complex (e.g. with dynamic scheduling). Sercos development effort for slave devices is assumed to be similar to EtherCAT, since real time part is handled in hw, too. Development Effort for CC-Link IE Field are difficult to determine, since the ASIC manuals are not available (at least not in Europe). Master Costs: Modbus/TCP, Ethernet/IP, Profinet I/O and EtherCAT masters do not require a dedicated plug in card. Since EtherCAT masters typically only send one frame per cycle, the additional CPU load on the master is much lower than with the others in this group. For hard real time applications, Profinet IRT, CC-Link IE, Powerlink and Sercos-III require special dedicated master cards with communication co-processors. For soft realtime requirements, Powerlink and Sercos-III can also be implemented with SoftMaster. Infrastructure Costs: Whilst Modbus uses switches (but no special ones), Ethernet/IP (+ typically Profinet RT) require manageable switches (Ethernet/IP with IGMP support). Depending on the topology, the integrated hubs (Powerlink) or switches (Profinet-RT) or special switches (Profinet-IRT, CC-Link IE) are sufficient - if not, external hubs or special switches are required. Sercos-III and EtherCAT do not require switches or any other active infrastructure components. Industrial Ethernet Technologies Page 137 © EtherCAT Technology Group, August 2011 RTE Technology Comparison: Summary Classification Strategic Topics (I) Profinet Modbus /TCP Ethernet /IP ProfiNet RT Powerlink ProfiNet IRT CC-Link IE Sercos III EtherCAT +* o +* +* + ++ ++ ++ ++ o ++ ++ + ++ ++ ++ ++ o + ++ Ethernet/IP Size of supporting organization CC-Link IE ++ +* Sercos III Worldwide User Group? Powerlink Modbus/TCP Time to Market EtherCAT Summary (V3/Gbit?) o (new IRT Version in 2011) o * Not all ODVA or PTO/PNO or CLPA members support Ethernet © EtherCAT Technology Group Industrial Ethernet Technologies User Group Size: No. of members in the user group is not crucial, but may serve as an indicator for the acceptance. As of August 2011, the EtherCAT Technology Group has 1750 member companies (membership free of charge*), Sercos International has 49 member companies**. EPSG (Powerlink) has 66 member companies***. ODVA has 277 member companies****. Profibus International (PI) consists of 25 regional organizations with a total of over 1400 members (Siemens is 25 x member), and CLPA***** has 1548 members, but their membership is predominantly fieldbus (Profibus, CC-Link) related. ModbusTCP is so widely used that the Modbus IDA membership of 69 members****** only does not reflect its acceptance. Worldwide User Group: ODVA and PI are present worldwide – as is ETG, with offices in Europe, North America, China, Korea and Japan. CLPA and Sercos have offices in Europe, North America and Japan. Time to Market: Modbus/TCP is available since 1999. Ethernet/IP since 2001. Profinet RT has entered the market in 2005. Powerlink V3 is expected for 2011, Powerlink V2 is available since 2007, the B&R proprietary version 1 is shipping since end of 2002. The next generation Profinet IRT is expected for 2013. CC-Link IE Control is not available for 3rd parties, CC-Link IE Field was introduced in 2010. First Sercos-III V1.1 devices were shipped end of 2007. EtherCAT is used in series applications since end of 2003. * since ETG membership is free of charge, membership figures should not be compared 1:1 with the other organizations. ** according to website www.sercos.de/www.sercos.com as of Aug 2011. ***according to EPSG Publication “PowerlinkFACTS” published in November 2007. In April 2007, there were 71 member companies. Since then now new membership figures published. **** according to www.odva.org as of Aug 2011 ***** CLPA website claims 1548 members as of July 2011, but lists only about 200. There used to be a free of charge membership option – maybe this is the reason for the difference. ***** according to www.modbus-ida.org as of Aug 2011 Industrial Ethernet Technologies Page 138 © EtherCAT Technology Group, August 2011 RTE Technology Comparison: Summary Classification Strategic Topics (II) Profinet Ethernet/IP Special Hardware used? IE CC-Link Modbus /TCP Rate? (CIP Sync) ++ International + - + (CIP Sync) Modbus/TCP EtherCAT Standardization ProfiNet RT ++ ++ ++ - Sercos III Powerlink Adoption Ethernet /IP + + Powerlink CC-Link IE Sercos III EtherCAT o - - - o (S: HUB FPGA) (M+S) (M+S) (M+S) (S) o -- -- o ++ + (+) + + o - (2003-2006) (since 2006) + ProfiNet IRT + (IRT) (IRT+) Summary © EtherCAT Technology Group Industrial Ethernet Technologies Special Hardware Used: Modbus/TCP, Ethernet/IP (not: CIPsync) + Profinet RT can be implemented with standard hardware chips. For Powerlink, the integrated hub is implemented as FPGA, since 100MBit/s hub chips are obsolete. Profinet IRT, CC-Link and Sercos-III require special chips in master and slave, EtherCAT requires an EtherCAT Slave Controller (FPGA or ASIC) but no special chips, cards or co-processors in the master. Adoption Rate: Modbus TCP has been used for many years. Ethernet/IP, Profinet RT are spreading. Since 2007: hardly any new Powerlink products. Potential Profinet IRT vendors wait for technology stability (IRT+). CC-Link IE Control: only Mitsubishi products (except cable + connectors), CC-Link IE Field: very few non-Mitsubishi products so far. Sercos-III 1.1 started shipping in December 2007. EtherCAT: large selection of master and slave devices from large variety of vendors (e.g. over 90 different servo drive vendors, 60 I/O device vendors, over 120 master vendors); more than 1200 implementation kits sold, many more devices expected soon. International Standardization: As far as international standardization is concerned, all are part of IEC 61158 and IEC 61784-2 since Oct 2007 – the only exception is CC-Link IE, which is expected to become an IEC standard in 2013 (only the application layer, though) Modbus-TCP: Communication Profile Family (CPF) 15, IEC 61158 Type 15 Ethernet/IP: CPF 2, IEC 61158 Type 2 Profinet: CPF 3, IEC 61158 Type 10 Powerlink: CPF 13, IEC 61158 Type 13 CC-Link IE: CPF 8, IEC 61158 Type 23 (NWP submitted) Sercos-III: CPF 16, IEC 61158 Type 19 EtherCAT: CPF 12, IEC 61158 Type 12 Industrial Ethernet Technologies Page 139 © EtherCAT Technology Group, August 2011 Classification Profinet Ethernet/IP CC-Link IE Sercos III Powerlink Modbus/TCP EtherCAT Thank you! Summary © EtherCAT Technology Group Industrial Ethernet Technologies
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