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Industrial Ethernet Technologies: Overview

1. 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 It is interesting to note that this announcement seems to imply that Rockwell a Sercos vendor in the past has turned down Sercos lll and tries to push an own motion bus approach Ethernet IP Summary et gt Approaches Conclusions e Network made for many Bytes of information per connection Modbus TCP Not intended for Drives and I O Bit sized connections gt Ethernet IP Technical Issues e Performance not convincing use ControlNet e Ethernet IP uses broadcast telegrams e requires complex router configuration e g IGMP snooping to avoid frame flooding of connected manufacturing and corporate networks e Filter algorithm implementations differ within switches therefore IT specialist may be needed in real life situations gt Powerlink gt PROFINET gt SERCOS Ill gt EtherCAT Strategic Issues gt S ee e Relatively slow adoption rate outside Rockwell world February 2008 Industrial Ethernet Technologies A quote from a Rockwell employee if you need more performance use Controln
2. IP EtherNet CSMA CD EtherNet Physical Layer Data Link Physical Industrial Ethernet Technologies ControlNet Transport ControINet CTDMA ControlINet Phys Layer DeviceNet Transport CAN CSMA NBA DeviceNet Phys Layer CompoNet Transport CompoNet Time Slot CompoNet Phys Layer 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 fy Ethernet IP Functional Principle ihe eA gt gt Approaches Consumer Producer Model e Advantage very efficient for slave to slave Communication gt Modbus TCP e Disadvantage requires Broadcast communication and thus filtering in each device gt Ethernet IP 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 gt EtherCAT gt Powerlink gt PROFINET gt SERCOS III broadcast communication gt Summary February 2008 Industrial Ethernet Technologies Ethernet IP Switch Router Issues cn ann gt Approaches CONCLUSIONS In this paper we have characterized the EtherNevIP
3. e First SERCOS III V1 1 drives were shipped in Dec 2007 gt Summary February 2008 Industrial Ethernet Technologies This means that as of beginning of 2008 Sercos Ill field deployment and application experience starts all over again On the other hand since hardly any Sercos lll devices were shipped before 2008 this may not be a major problem SERCOS III Summary II SERCOS interface gt Approaches e High Performance Industrial Ethernet Approach e Focus on drives so far very limited I O sensor valve etc support gt Modbus TCP e Topology line and ring only no branches no drop lines gt Ethernet IP no hot connect of segments not more than 254 nodes e Technology is hardly field proven yet less than 1000 nodes deployed 4 2007 Requires dedicated master card for hard real time gt Powerlink PROFINET Use of Internet Technologies requires Cycle Times gt 250us e Depending on configuration IP traffic can be slow gt EtherCAT e Has been the approach that is the latest on the market e Slow adoption rate few Sercos I II vendors move to Sercos III gt Summar 5 e EtherCAT supports the same device profile application layer February 2008 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 ot
4. So far there are few known if at all automation applications using this technology adoption rate is slower than expected initially Since the Ethernet implementation of the standard uses UDP IP stack processing times limit the accuracy in case of pure software implementations It is possible however to achieve good results by employing chips and switches with built in IEEE1588 support first silicon has been introduced by Intel and Hyperstone One can argue if these can be considered standard Ethernet Chips Just to clarify this one No objections to use special hardware in order to achieve better real time behavior or reduce costs But then this should be clearly stated IEEE 1588 will almost certainly be an important time synchronization protocol but as of today it is not yet gt Approaches 1588 gt Modbus TCP a Extension f gt Ethernet IP TCP gt UDP SS User Datagram Protocol icit ulus gt Powerlink Da A gt PROFINET bibssages Ve optional Hardware gt SERCOS III SS support for gt EtherCAT gt Summary CIP Common Industrial Protocol February 2008 Industrial Ethernet Technologies 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 will turn the class A approach Ethernet IP into the class C approach Ethernet IP
5. e Master uses Standard Ethernet Controllers Ethernet HDR 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 EtherCAT Ethernet onthe Fly s EthercaT gt Approaches Minimal protocol overhead via implicit addressing gt Modbus TCP gt Ethernet IP gt Powerlink gt PROFINET e Optimized telegram structure for decentralized I O gt SERCOS III e Communication completely in hardware maximum performance e no switches needed if only EtherCAT devices in the network gt Summary e Outstanding diagnostic features e Ethernet compatibility maintained February 2008 Industrial Ethernet Technologies EtherCAT is very effective even with small amounts of data per slave device s
6. gt Summary February 2008 Industrial Ethernet Technologies 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 uC may have typical response times of gt 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 Modbus TCP Future Modbus IDA gt Approaches
7. 1 a Safety over EtherCAT Technology Approach gt Approaches gt Modbus TCP Standard Standard gt Ethernet IP application application gt Powerlink Safety over EtherCAT gt PROFINET l EtherCAT EtherCA Reread gt SERCOS III _ protocol n gE eum EtherCAT acts as a real black channel February 2008 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 gt Approaches gt Modbus TCP gt Ethernet IP gt Powerlink gt PROFINET gt SERCOS Ill gt Summary February 2008 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 gt Approaches gt Modbus TCP gt Ethernet IP gt Powerlink gt PROFINET SERCOS Ill gt EtherCAT gt Summary February 2008 Industrial Ethernet Technologies EtherCAT Only 2nd Ethernet Port required no special Interface Card If the line is turned into a ring there are two
8. EPSG announced Gbit Powerlink claiming the network performance would be 10 times 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 Doing the maths shows that the performance gain would be minimal Depending on the configuration a factor of 1 38 2 can be expected if the same frame length is not changed from 100 MBit s IEEE802 3 specifies 512 Byte minimum frame payload for GBit hub based systems There are indications however that it is intended to use switches in conjunction with Gbit Powerlink In this case the additional delay introduced by switches instead of hubs will undo the performance gain of the higher transmission rate so it can be expected that Gbit Powerlink will be slower than 100MBit Powerlink In addition announcing GBit Powerlink further confuses the potential implementers should he implement V1 V2 or wait for Gbit Furthermore chips in Gbit mode draw much more power which would be a problem for many automation devices Ethernet Powerlink Standardization Group e EPSG originally hosted by Institute of Embedded Systems Zurich University Winterthur Switzerland e In 2006 EPSG Office moved to ETHERNET marketing agenc
9. In addition to the RT classes Profinet has introduced see IEC 61 784 2 Application Classes lsochronous for motion control Non isochronous for factory process building automation Redundancy Classes MRP Media redundancy protocol MRRT Media redundancy for real time 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 is supported in Conformance Class B C only 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 though in principle unmanaged switches can be used with Conformance Class A Profinet networks they have to be selected very carefully IT support required see also EF TA 2007 Conference Paper by Iwan Schafer Max Felser Berne University of Applied Sciences Topology Discovery in PROFINET http www felser ch download E TFA 01 2007 pdf Next Generation Profinet IRT gt Approaches e On press conferences in Nov 2007 PNO PTO published gt Modbus TCP performance comparsions with EtherCAT e It was found that in typical applicatio
10. Limited Line Topology gt SERCOS III Hub Delays gt EtherCAT gt Summary gt Ethernet IP gt Powerlink gt PROFINET February 2008 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 ETHERNET MEE OWE Powerlink Timing POWERLINK e Overall Network Performance depends on Slave Implementation e Fast response time requires powerful processors on the slave gt Modbus TCP controller side or implementation in Hardware FPGA A lot of idle time on the media gt Approaches gt Ethernet IP gt Powerlink gt PROFINET gt SERCOS Ill gt EtherCAT gt Summary February 2008 Industrial Ethernet Technologies The diagram is misleading A typical poll response up to 46 Bytes of data is 7us and thus shorter than the typical response delay time of a slave device Or in other words the idle tim
11. SERCOS III gt EtherCAT gt Summary February 2008 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 Safety over EtherCAT Features EtherCAT gt Approaches e TUV certified technology gt Modbus TCP e Developed according to IEC 61508 EEE e e Protocol meets Safety Integrated Level SIL 4 e Device implementations typically SIL 3 gt Powerlink e Suitable for functional safe I O as well as for gt PROFINET functional safe motion control e Variable CRC size for minimal overhead gt SERCOS III e Safe Parameter Download at boot up most gt EtherCAT simple device exchange possible SUEY e Safety devices available since end of 2005 February 2008 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
12. 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 gt Approaches gt Modbus TCP gt Ethernet IP gt Powerlink gt PROFINET gt SERCOS III gt EtherCAT gt Summary February 2008 PROFINET and INTERBUS the Interbus View Management Level Control Level Complex field devices Simple field devices AGOG INTERBUS nfo there is life below PROFINET Picture sourced from Interbus Club website Industrial Ethernet Technologies Due to system complexity and costs Interbus as well as Profibus expect life below Profinet PROFINET Summary gt Approaches e 3 different Versions Proxy Approach Soft Real Time Ilsochronous Real Time gt Modbus TCP e Proxy Approach vaporware gt Ethernet IP e RT rather complex Profibus replacement but will have market share due to support by Siemens gt Powerlink e There will be underlying networks for cost reasons e IRT for motion control meets motion control requirements gt PROFINET but very complex and
13. and Polling over Ethernet similar to CANopen and DeviceNet both use CAN Powerlink new in Version 2 What s New in ETHERNET Powerlink V2 gt Approaches EgETHE RNET gt Modbus TCP ETHERNET Addressing gt Ethernet IP MAC Addressing conform to IEEE 802 3 Unique MAC Address for every device thus V2 incompatible gt Powerlink Different to EPL V1 with V1 gt EPL Addressing via EPL Node ID 8 Bit gt PROFINET gt Used in EPL Frames Used for IP Address 192 168 100 EPL Node ID gt SERCOS III Easy Address assignment via Switch possible gt EPL Node ID Assignment EPL Node ID_ Description o gt EtherCAT gt Summary Diagnostic device EPL to legacy Ethernet Router EPL broadcast Source Powerlink Seminar Proceedings Stuttgart 16 6 2004 EPSG website February 2008 Industrial Ethernet Technologies In Powerlink Version 1 all nodes used the same MAC address which violates IEEE 802 3 Thus the MAC layer of Version 1 is incompatible with Version 2 Protocol addressing EPL IP has changed as well The Powerlink Spec V2 demands that IP capable nodes have a fixed private IP address This means that even in a future open mode routers with NAT have to be used to access Powerlink nodes via IP protocols Powerlink new in Version 2 What s New in ETHERNET Powerlink V2 Framestructure has ETHERNET Approaches changed as well ad gt Modbus TCP ETHERNET Frame Handlinc gt Etherne
14. based on figures assumptions and assessments that cannot be given in full detail one may come to a different conclusion However some like 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 lll and about 10 15 times faster than Powerlink 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 lt lt 1us With Sercos lIll and Powerlink the jitter depends on the communication jitter of the master with Profinet IRT it depends on the number of cascaded switches All three technologies claim a jitter of lt 1us as does ClPsync Throughput if IP data with the best effort approaches Modbus Ethernet IP and Profinet I O 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 Powerlink suffers from half duplex communication and overall poor bandwidth utilization due to polling Sercos lll suffers from the delay introduced by large no of casca
15. communication paths to each device redundancy With EtherCAT even without special hardware in the master a second Ethernet port is sufficient By using this device exchange at run time hot swap is feasible as well EtherCAT is simpler to configure Ether AT Smads Addressing e No manual address setting required gt Modbus TCP e Addresses can be kept no new addressing if nodes are added gt Ethernet IP Topology e Automatic topology target actual comparison possible gt Powerlink Diagnosis gt PROFINET e Diagnosis information with exact localization Network planning gt SERCOS III e Performance independent of slave implementation e g stack features UC performance gt EtherCAT e Performance widely independent from topology no switches hubs e Performance more than sufficient therefore no tuning required gt Summary any more default settings do the job February 2008 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 uC 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 mor
16. e In April 2007 Schneider Electric joined ODVA as principal member and announced Ethernet IP products for 2008 e ODVA announced to provide compatibility of Modbus TCP devices with networks built on CIP e A Modbus Integration SIG was established to specify the gt Powerlink CIP to Modbus Translator gt Ethernet IP gt PROFINET gt SERCOS Ill gt EtherCAT e Future of Modbus TCP looks uncertain since driving force seems to walk away gt Summary February 2008 Industrial Ethernet Technologies 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 Schneider replaces one non real time protocol by another one gt Approaches gt Modbus TCP gt Ethernet IP gt Powerlink gt PROFINET gt SERCOS Ill gt EtherCAT gt Summary February 2008 Lf EtherNet IP e ODVA Rockwell Approach IP stands for Industrial Protocol A e CIP Common Industrial Protocol common object library for Ethernet IP ControlNet DeviceNet CompoNet e Follows Approach A Ethernet IP Overview Device Profiles AATTEET Me Robots Other CIP Application Layer Application Object Library EtherNet IP Pee Application CIP Data Management Services Explicit Messages I O Messages CIP Message Routing Connection Management Encapsulation Transport Network
17. e Standard Controllers are RT in PROFINET provides similar Real Time properties sg like PROFIBUS sensitive for IP Multicast Traffic gt Approaches Process data gt Summary Cycle times can be realized in the range of 5 to 10 ms February 2008 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 should be faster one can read this statement as follows If Profibus performance is sufficient but Profibus is not expensive enough Profinet RT is an alternative _ PROFINET V2 RT and V3 IRT V2 Real Time RT e Software Solution with Standard Controller Modbus TCP e Usage of Standard Network Components e Real Time as good as provided by Switching Technology VLAN Tagging Prioritization IEEE802 1q gt Approaches gt Ethernet IP gt Powerlink PROFINET V3 Isochronous Real Time IRT Synchronization of all nodes e Bandwidth reservation for isochronous Data e Requires Special Hardware ASIC gt SERCOS III gt EtherCAT gt Summary February 2008 Industrial Ethernet Technologies Profinet IRT is a class C approach which introduces special hardware in order to achiev
18. expensive gt SERCOS III e IRT expected to be predominantly Siemens only like Profibus DPV2 for Motion Control gt EtherCAT gt Summary February 2008 Industrial Ethernet Technologies Profinet RT is not low cost requires a lot of code and is not high performance but 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 RT 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 aimed at servo motion control applications and will just like Profibus MC be 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 DriveClig which uses Ethernet physical layer only us SE
19. gt Approaches gt Modbus TCP gt Ethernet IP gt Powerlink gt PROFINET gt SERCOS III gt EtherCAT gt Summary February 2008 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 work for is member of ODVA PNO PTO Sercos ETG 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 and USA as well as on several other occasions altogether attended by far more than 1000 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 slid
20. or not Powerlink For any installation with more than 20 25 devices network branches are required e The network topology layout requires a top down approach e The planning process will mandate the layout and wiring of a configuration gt EtherCAT e performance data is true for a specific topology ONLY e Topology restrictions apply when designing a network gt Summary with a required performance gt SERCOS III February 2008 Industrial Ethernet Technologies The strong but 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 gt Approaches gt Modbus TCP Hardware assisted Profinet Profinet IRT gt Ethernet IP RT Class 2 RT Class 3 gt Powerlink time slicing without with topology oriented topology planning network planning defined timing for gt PROFINET each connection path Soft Real Time with gt SERCOS Ill Hardware Support Hard Real Time gt EtherCAT a All variants are called gt Summary Profinet IO February 2008 Industrial Ethernet Technologies In order to avoid the complex topology network planing process an intermediate approach has been introduced RT Class 2 within Siemens also called IRT Flex using Profinet chips e g ERTEC High priority network traffic is sent in the IRT time slice but withou
21. 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 Ethernet IP Topology ihe NAT e Standard Switched Ethernet Topology e By nature unpredictable gt Modbus TCP Switch Stack Delays e Network separation by gt Approaches gt Ethernet IP e Limited Real Time gt Powerlink Capabilities gt PROFINET gt SERCOS IlI gt EtherCAT gt Summary February 2008 Industrial Ethernet Technologies Even though the switch delays are unpredictable by nature the delays introduced by the software stacks are much more significant Ethernet IP Performance et gt Approaches e Rockwell implementation allows few connections 1 32 e Minimum Cycle Time RPI Requested Packet Interval gt Modbus TCP is dependent on number of connections e Each Device can have multiple Connections gt Ethernet IP gt Powerlink assumed all connections request same RPI scan time min_RPI number of connections x 2 no of frames second ee No o
22. 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 uC 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 Next Generation Profinet IRT gt Approaches l e When taking all EtherCAT Features into account the gt Modbus TCP performance comparison looks different Relative cycle times gt Ethernet IP gt Powerlink gt PROFINET gt SERCOS III d ECT IRT acc to PNO Paper gt EtherCAT ae gt Summary 0 20 40 60 80 100120 140 160 180 200 220 240 260 280 300 Bytes per node February 2008 Industrial Ethernet Technologies This slide shows the relative performance comparison if all the EtherCAT Features are taken into account purple line The blue line shows the comparison according to the PNO paper Next Generation Profinet IRT gt Approaches l a l l l e And in this view the difference is even more obvious gt Modbus TCP Cycle times 2 ss b gt Powerlink j L gt SERCOS Ill S e J ECT acc to PMO Paper aP mr Hhert AT gt Summary oO 20 40 60 80 100 120 140 160 180 200 220 240 Bytes per node February 2008 Industrial Ethernet Technologies And here
23. the absolute cycle times are shown According to the Siemens product manuals all but one current Profinet IRT master implementations start at 0 5 cycle time so that shorter cycle times are of more theoretical nature Please note that one major EtherCAT feature is still not included in the comparison the ability to combine short and longer cycle times So e g drives can be updated faster than shown if the update rate of other devices such as analogue inputs is decreased Next Generation Profinet IRT gt Approaches l l e In particular if one looks at the most relevant area lt 60 Bytes gt Modbus TCP Cycle times gt Ethernet IP gt Powerlink gt PROFINET gt SERCOS III in aa a 2 wa lt a ECT acc to PHO Paper Profinet IRT gt EtherCAT a EtherCAT gt Summary 20 40 Bytes per node February 2008 Industrial Ethernet Technologies And this cycle time comparison looks at the most relevant are of up to 60 bytes average process data size per node We have not seen a control system yet in which the average process data size per node exceeded this value Next Generation Profinet IRT gt Approaches l Sa l e PNO also showed a special application scenario comb gt Modbus TCP structure with 8 branches in which the nodes in the branch lines are only updated every 8th cycle in which Profinet IRT gt Ethernet IP will allegedly exceed EtherCATs Performance e Also a new Profine
24. 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 J What is IEEE 1588 Fs e A method for precision time synchronisation widely protocol independent tailored to requirements of distributed measurement and control systems e If applied to Ethernet based on UDP IP as of today gt Ethernet IP gt P 1588 code amp hardware Grand Master Clock gt Approaches gt Modbus TCP gt Powerlink Ivpical Slave Clock GPS gt PROFINET ji gt SERCOS IlI gt EtherCAT Only Slave Port of Boundary Clock gt Summary lvpical Master Port of Boundary Clock Source introduction_to_1588 pdf by IEEE February 2008 Industrial Ethernet Technologies IEEE 1588 is a protocol for time synchronization that is or will be used by a variety of systems Ethernet IP Profinet Powerlink EtherCAT will also Support external time synchronization with IEEE1588 Interoperability is improved by regular plug fests IEEE 1588 is a published standard but the technology is currently being modified or enhanced by a study group This is one reason why some vendors have postponed their implementation It is the goal that the resulting protocol varieties will be interoperable Hopefully they will be supported by all implementations hw sw
25. traffic and provided recommendations gt Modbus TCP aimed to optimize network and ultimately control system performance These recommendations are based on utilization of switching devices in the EtherNet IP infrastructure that possess specific features like IGMP Snooping aiming lo minimize end gt Ethernet IP device and switch loading with unwanted traffic as well as propagation of the such a traffic to and from a plant network gt Powerlink ISSUES The following issues have been identified during performance and interoperability tests of ak STA B gt PROFINET EtherNev IP products performed by Rockwell Automation what they do and how they work between network switch vendors and in some cases even between different classes of products produced by the same vendor Lack of IP multicast control support of the IEEE 802 3 spanning tree protocol and gt EtherCAT other appropriate features in some low end switches which considerably limits their cs pap Th use in non isolated EtherNevIP networks gt Summary e Lack of industrial high end Layer 2 and Layer 3 switches from a technical paper found on the ODVA website gt SERCOS III February 2008 Industrial Ethernet Technologies 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
26. 00 gt Powerlink with IP 500 channel nolP channel gt PROFINET O E o Oo gt O gt SERCOS Ill gt EtherCAT 4 5 6 gt Summar y Application Examples February 2008 Industrial Ethernet Technologies A graphical view for the previous table In average over 9 different application scenarios EtherCAT is 2 9 times faster SERCOS III IP Handling I JJSERCOS interface e At Boot Up Slaves are in NRT Non Real Time Mode until they see first RT Frame gt Approaches gt Modbus TCP e In NRT Mode Slave Chips Protocol behave like 3 port Switches Handler eal e Each node needs a MAC Address e Switch Behavior depends on Implementation Store and Forward Default or PROFINET Cut Through High End e Forwarding Delay depends on No of Nodes and on Switch Implementation gt EtherCAT e Typical Store and Forward Delay per Node and Direction 10 125us depending on Frame Length gt Powerlink gt Summary February 2008 Industrial Ethernet Technologies It will be interesting to see how the IP communication over a large number of cascaded switches behaves SERCOS III IP Handling Il J SERCOS interface e In Non Real Time Mode no Master active direct IP communication with Slave Devices is possible gt Approaches gt Modbus TCP gt Ethernet IP gt Powerlink gt PROFINET e In Real Tim
27. 006 Sercos launched Easy l 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 II drive implementation Alternatively the Hilscher netX chip can be used which also supports EtherCAT Profinet SERCOS Ill Performance Overview II SERCOS interface Cyclic Cycle No of No of MDT AT data time devices 1 devices 2 gt Modbus TCP 12 Byte 62 5 us 16 1 1 E OEE 16 Byte 125 us 30 1 1 gt Approaches gt Powerlink 32 SETA 35 18 1 1 gt PROFINET 12 Byte 500 us 130 100 2 2 50 Byte 1 ms 100 85 4 4 32 Byte 1ms 140 120 4 4 gt EtherCAT 1 without IP channel 2 with IP channel 125 ps gt Summary Source Presentation at Real Time Ethernet Seminar Reutlingen March 2005 February 2008 Industrial Ethernet Technologies This performance data was published in March 2005 At cycle times below 250us there is no IP channel and thus no TCP IP support SERCOS Ill Performance Comparison JJSERCOS gt Approaches No of Nodes with given Cycle Time gt Modbus TCP Appli Cyclic cation Data gt Ethernet IP Sees gt Powerlink gt PROFINET gt SERCOS Ill gt EtherCAT gt Summary Cycle Time 31 25 us 62 5 us 125 us 250 us 250 us 500 us 1 ms 1 ms 1 ms February 2008 Industrial Ethernet Te
28. 0x88A Datagrams gt Summary aif it February 2008 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 EtherCAT is Industrial Ethernet EtherCAT gt Approaches e Connection to any Ethernet device via Switchport e Access to web server with standard browser gt Modbus TCP e Switchport can be implemented as device feature seperate device or software functionality in master gt Ethernet IP Switchport allows for hard real time capability with parallel Ethernet communication of any kind gt Powerlink gt PR
29. 1999 First spec V0 9 published in March 2001 Ethernet IP was first introduced in 2000 ee Yi Component Based Programming Approach 22 free gt Approaches vate Interface E O PRROFINEET CAA aa m la comprises more than just gt Modbus TCP Sh aa the communication Information gps e Approach may be fine for gt Ethernet IP 50 variables but how do Vendor A Vendor B i Bottle Cleaning Filling you handle 500 variables gt Powerlink this way PROFIBUS gt PROFINET gt SERCOS III mm mm PROFIBUS gt EtherCAT Z onmmaty mem e Pictures sourced from PTO PNO website February 2008 Industrial Ethernet Technologies 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 PROFINET V2 RT e First named Soft Realtime SRT e Best Effort Protocol with 5 10 ms typical cycle time and 15 jitter gt Modbus TCP e Modified Stack bypasses TCP and IP for Realtime process data e Aimed at and suited for PLC type applications including drive gt Ethernet IP control but not motion control e Requires substantial amount of software Field device 1MByte gt Powerlink Limitations e Soft Realtime Solution gt PROFINET with Influence by TCP traffic gt SERCOS III Inpredictable Queue delays in switches gt EtherCAT Stack delays
30. DON e Complex recursive optimization problem gt Modbus TCP e Configuration and System Planning isa process executed by a central Algorithm in the Engineering gt Ethernet IP System e Small change in input e g one more node may lead to Powerlink big change in output cycle time and thus performance due to unpredictable behavior of optimization algorithm gt PROFINET po L Strong interdependency between topology and gt EtherCAT performance gt Summary And This Algorithm is SIEMENS IP and not yet open February 2008 Industrial Ethernet Technologies 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 To our best knowledge the planning algorithm is not open gt Approaches e Line Branch Tree gt Modbus TCP Topology is supported e Cascading of switches in a line has limit of 20 25 devices gt Ethernet IP e this means branch star topology is the common design whether desired
31. OFINET gt SERCOS IlI gt EtherCAT gt Summary February 2008 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 gt Approaches gt Modbus TCP gt Ethernet IP gt Powerlink gt PROFINET SERCOS Ill gt EtherCAT gt Summary February 2008 EtherCAT Most flexible Topology EtherCAT 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 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 EtherCAT Gateways EtherCAT gt Approaches EtherCAT Performance allows for EtherCAT instead of PCI no card slots required any more gt Modbus TCP maximum system expandability with low cost fieldbus gateways seamless integration of fieldbus devices protects your investment gt Ethernet IP smooth migration path from fieldbus to EtherCAT gt Powerlink gt PROFINET gt
32. Powerlink interface based on standard chips The chip costs listed may be outdated meanwhile but it remains valid that the discrete design of a Powerlink slave interface is not a very cost efficient approach ETHERNET MEE Powerlink Interface Costs Il POWERLINK gt Approaches e Since discrete Interface is way too expensive gt Modbus TCP too slow too unpredictable Powerlink moved to FPGA implementation e SO now same situation as with PROFINET gt PROFINET SERCOS III and EtherCAT gt Ethernet IP gt Powerlink gt SERCOS Ill STOWE INK gt EtherCAT B C gt Summary February 2008 Industrial Ethernet Technologies EPSG has announced 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 amp R Lenze announced that the master managing node will now also be 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 fur Powerlink Computer amp Automation Magazine 12 2007 p 17 ETHERNET MEE OUR Powerlink Time to Mar
33. Process Data Communication only no bandwidth for acyclic communication ii Example 2 Hubs no Switches op aie carne arr EENE Eina anid EOS ve ETHERNET gt Modbus TCP gt Ethernet IP Cycle Time with 100 MBit s 323 us Cycle Time with 1 Gbit s 245 us gt Powerlink Performance Gain Factor 1 38 gt PROFINET For Example EtherCAT Cycle Time ee 52 Bus load 28 ps gt EtherCAT gt Summary February 2008 Industrial Ethernet Technologies In November 2006 EPSG announced Gbit Powerlink claiming the network performance would be 10 times 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 Doing the maths shows that the performance gain would be minimal Depending on the configuration a factor of 1 38 2 can be expected if the same frame length is not changed from 100 MBit s IEEE802 3 specifies 512 Byte minimum frame payload for GBit hub based systems There are indications however that it is intended to use switches in conjunction with Gbit Powerlink In this case the additional delay introduced by switches instead of hubs will undo the performance gain of the higher transmission rate so it can be expected that Gbit Powerlin
34. Profinet I O and Powerlink require substantial processing power and memory Using FPGAs Powerlink Sercos and EtherCAT achieve comparable cost levels assuming the Sercos implementation will use similar FPGA sizes the ASIC implementation of EtherCAT reaches or undercuts fieldbus cost levels 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 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 Powerlink Profinet IRT and Sercos Ill require special dedicated master cards with communication co processors Infrastructure Costs Whilst Modbus uses switches but no special ones Ethernet IP typically Profinet I O require manageable switches Ethernet IP with IGMP support Depending on the topology the i
35. RCOS Ill Features II SERCOS interface BAD EIOaCICS e Combining Sercos mechanism with EtherNet Physics Cc e 100 MBit network transmission rate e Hardware based synchronization and ring topology gt Ethernet IP e Integration of TCP IP channel e Cyclic and acyclic communication e Cross communication between slaves e Media redundancy support e Control recognizes the physical order of devices e 100BASE TX or POF based physical layer e Requires Special Master Card e maximum of 254 slave nodes per network e Line Ring Topology only gt Modbus TCP gt Powerlink gt PROFINET gt EtherCAT gt Summary February 2008 Industrial Ethernet Technologies The list of features of SERCOS III reads like the list of features of EtherCAT except the last three items II SERCOS interface AT Drive gt Approaches Telegram gt Modbus TCP gt Ethernet IP gt Powerlink PROFINET e Slaves extract and insert data on the fly e Master sends frames 2 or more per cycle 7 e Slaves process frames twice gt EtherCAT e IP data is inserted in gaps IP channel e Telegram structure fixed at run time gt Summary February 2008 Industrial Ethernet Technologies SERCOS III has adopted the EtherCAT functional principle processing Ethernet frames on the fly There are some main differences though SERCOS III separates input and output data in two frames so there are at minimum two frames per cyc
36. S Jitter is sufficient for Node Synchronization Source Presentation at Automation Summit Beijing June 2007 Industrial Ethernet Technologies In April 2007 Sercos International announced the development of a sercos lll 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 real time network using a soft master is depending on the performance of the hardware and the characteristic of the used operating system This means that e g with PC hardware and RTOS a synchronization accuracy of several us seems to be achievable For hard real time requirements Sercos recommends the hardware implementation of the master II SERCOS interface gt Approaches 1 FPGA solution Jij sER OsS NIERA gt Modbus TCP A Ay A Ofen Aa Cyclone II gt Ethernet IP gt Powerlink l l l 2 Integrating SERCOS III interface into universal communication controllers Cost effective gt SERCOS III Makes single chip devices possible Multi Protocol capability gt PROFINET XXXX XXXX ARM gt EtherCAT gt Summary e EthercaT fJSERCOS me Ether iio IP February 2008 Industrial Ethernet Technologies SERCOS III Controllers are FPGA based Later a hardcopy version may be added In order to push the adoption of the SERCOS I O profile which was published in Nov 2
37. T and EtherCAT via special switchports Cable Redundancy For Modbus TCP Ethernet IP and Profinet I O switches with spanning tree protocol can be used to establish cable redundancy between the switches only For Powerlink a redundancy option has been announced solution and effort unclear Profinet IRT aims for redundancy but the planning algorithm for a redundant IRT topology is so complex that its implementation is questionable Sercos ll 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 known safety protocol for Modbus TCP The safety approaches of the other technologies differ regarding availability Safety over EtherCAT products are shipping since end of 2005 gt RTE Technology Comparison gt Approaches S P CJETHERNET Modbus Ethernet ProfiNet ProfiNet Sercos RT I O i IRT III gt Modbus TCP gt Ethernet IP pa l Node Costs pees gt Powerlink w FPGA rey w w FPGA gt PROFINET Development gt SERCOS III Fina gt EtherCAT Infrastructure mfe fe of gt Summary Costs Switch Switch Switch Switch no no integr integr Switch Switch Requires Special Master Card with Co Processor February 2008 Industrial Ethernet Technologies Node Costs Whilst Modbus TCP due to limited real time claims can be implemented on 16bit uC Ethernet IP
38. Ts performance e 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 eEtherCAT 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 PROFINET ASIC Pricing gt Approaches PO ERTEC 200 ERTEC 400 Functionality PROFInet RT IRT PROFInet RT IRT gt Modbus TCP IEEE 1588 IEEE 1588 ARM 9 Processor ARM 9 Processor 2 Port Switch with PHY 4 Port Switch no PHY PCI Interface RMII Interface 4port gt Ethernet IP gt Powerlink Application field Single drives High end Motion Controller Comparable field devices Network components gt PROFINET ASIC Technology 0 15 um Technology 0 15 um Technology 304pin BGA 19 x 19 mm 304pin BGA 19 x 19 mm gt SERCOS III Pricing SVS 30 00 order size 350 units order size 350 units gt EtherCAT Pricing shows that PROFlinet is more on the complex field gt Summary device network side than on the cost efficient I O system side February 2008 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 1 2007
39. al 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 Publicly Available Specification 62407 which can be obtained from the IEC webstore 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 IIl 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 vari
40. chnologies interface SERCOS III EtherCAT No of No of Devices Devices without IP with IP channel Channel remaining Bandwidth for IP 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 even at the shortest cycle times and with many more nodes than the corresponding SERCOS III network EtherCAT still supports IP communication SERCOS Ill Performance Comparison JJSERCOS interface gt Approaches Sees Time SERCOS III EtherCAT given No of Nodes gt Modbus TCP No of No of Appli Cyclic Devices aon Bele Time without IP with IP Cycle Time E gt Ethernet IP aa eo channel Channel with IP Cycle Devices Devices o or Resulting 8 Byte 31 25 us 8 gt Powerlink 12 Byte 62 5 us 16 gt PROFINET 16 Byte 125 us 30 12 Byte 250 us 67 gt SERCOS IlI 32 Byte 250 us 35 12 Byte 500 us 130 50 Byte 1 ms 32 Byte 1 ms 12 Byte 1 ms gt EtherCAT gt Summary February 2008 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 SERCOS Ill Performance Comparison JJSERCOS interface gt Approaches Cycle Time Comparison 1000 4 gt Modbus TCP m E SERCOS III with IP 800 gt Ethernet IP a E EtherCAT 6
41. ded switches in Realtime Mode gt RTE Technology Comparison gt Approaches S P e CJETHERNET Modbus Ethernet ProfiNet ProfiNet Sercos Wiring RT I O IRT Ili gt Modbus TCP gt Ethernet IP Topology Flexibility gt Powerlink gt PROFINET Line O O ma 5 mla m Structure 10 25 254 65535 gt SERCOS III COTS gt EtherCAT Infrastructure P F f O Components Switch Router ino Connector etc Switch February 2008 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 Sercos lll line and ring only Profinet IRT line tree star drop lines but limited no of nodes and strong interdependency between topology and performance Powerlink line tree star drop lines but strong limitation due to hub delays Line Structure ModbusTCP Ethernet IP Profinet I O do not support line topology With Powerlink only few nodes in line due to hub delays According to B amp 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 to 20 Sercos lll specifies up to 254 nodes in line EtherCAT supports up to 65535 Commercially Off The Shelf COTS Infrastructure Components Ethernet IP asks for manageable
42. e Mode Master active link to IP Device e g notebook has to be physically disconnected gt EtherCAT gt Summary February 2008 Industrial Ethernet Technologies In a non redundant network layout the port on the last device can be used to connect a configuration notebook However this has to be physically disconnected before enabling the master There are plans to change this in a future release of Sercos lll SERCOS III IP Handling III JJSERCOS interface for IP Access to Slave Devices in RT Mode or for IP Access to Slave Devices without Plugging Unplugging gt Modbus TCP e Gateway Device or Master with Gateway Functionality Required gt Approaches gt Ethernet IP gt Powerlink gt PROFINET gt SERCOS III gt EtherCAT gt Summary February 2008 Industrial Ethernet Technologies In order to allow for IP access to slave devices at run time of the network 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 SERCOS III IP Handling IV JJSERCOS interface In RT Mode IP Traffic is inserted in IP Channel e During IP Channel Slave is in Switch Mode gt Approaches gt Modbus TCP gt Ethernet IP gt Powerlink e If IP Channel is short Store and Forward Implementations have PROFINET to delay the forwarding of larger f
43. e configuration a factor of 1 38 2 can be expected if the same frame length is not changed from 100 MBit s IEEE802 3 specifies 512 Byte minimum frame payload for GBit hub based systems There are indications however that it is intended to use switches in conjunction with Gbit Powerlink In this case the additional delay introduced by switches instead of hubs will undo the performance gain of the higher transmission rate so it can be expected that Gbit Powerlink will be slower than 100MBit Powerlink In addition announcing GBit Powerlink further confuses the potential implementers should he implement V1 V2 or wait for Gbit Furthermore chips in Gbit mode draw much more power which would be a problem for many automation devices a Gigabit Powerlink 10 x faster POWERLINE Approaches e Powerlink Performance Gain by changing from 100 Mbit s to 1 Gbit s ca Factor 2 e Probably no Gain at all if Switches are used for Gbit gt Ethernet IP e Effort e 8 instead of 4 Wires Field Mounting e no M12 gt PROFINET e Power consumption significantly higher PHY MAC gt Modbus TCP gt Powerlink gt SERCOS III ee e Ergo Powerlink has a Performance Issue which is not solved gt EtherCAT by announcing Gbit Powerlink e 100Mbit already outdated Gbit not yet available if you were Z onmmaty Device Vendor would you implement Powerlink now February 2008 Industrial Ethernet Technologies In November 2006
44. e on the half duplex media is even longer than indicated ETHERNET Sil Some POWERLINK gt Approaches Application Example e 6 Drives e 2 I O Nodes gt Ethernet IP e 400 m Cable Length e Cycle Time 291 us gt Modbus TCP gt Powerlink gt PROFINET For Comparison gt SERCOS IlI e Sercos ll 16 Mbaud lt 250 US gt EtherCAT e EtherCAT 17 us gt Summary February 2008 Industrial Ethernet Technologies The performance examples are taken from the Powerlink spec Version 2 There a Powerlink slave response time of 8us and a master response time of 1 us are assumed gt Approaches gt Modbus TCP gt Ethernet IP gt Powerlink gt PROFINET gt SERCOS Ill gt EtherCAT gt Summary February 2008 ETHERNET Sil Some Powerlink Interface Costs I POWERLINK e Powerlink claimes to use e g Standard Ethernet chips only Net 50 e But Hub Chips become obsolete gt ASIC or FPGA required e Nodes need a 32 bit CPU and infrastructure Total cost for the interface made of Standard Ethernet chips around 25 to 30 Industrial Ethernet Technologies XScale425 Hyperstone approx 2 5 i 32 bit CPU i N e g ARM7 NIOS approx 1 approx 1 MAC approx 15 20 approx 2 x 1 10 ioi approx 25 30 approx 2x 1 RJ45 RJ45 This hardware block diagram was drawn by an EPSG member company and shows the hardware effort for a
45. e set a fair and technology driven comparison of Industrial Ethernet Technologies Nuremberg February 2008 Martin Rostan m rostan ethercat org Industrial Ethernet Technologies Overview gt Approaches _ Modbus IDA gt Modbus TCP n gt Ethernet P gt ODV Networks Built on a Common Industrial Protocol gt Powerlink lt gt ETHERNET gt SERCOS III SERCOS interface N gt EtherCAT lt TF th e CAT i Technology Group gt Summary February 2008 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 Basic Slave Device Approaches gt Approaches e Completely TCP UDP IP based e Ordinary Ethernet Controllers and Switches gt Modbus TCP Principle applied by Parameter Data and Real Time Data E gt Powerlink z EtherNet IP gt PROFINET Software Layer 5 7 AOE Lene topupp OE r OL TAAL E mi NJET eS Layer 1 2 Ordinary Ethernet Controller Slave Architecture gt EtherCAT Hardware gt Summary February 2008 Industrial Et
46. e sufficient performance and synchronicity for motion control applications PROFINET V3 IRT Features e Timeslicing Approach by special Switch ASICs e Switches can be integrated into devices Modbus TCP e Topologies Line up to 25 nodes Branch Tree supported e Cycle Time 250 us to 4 ms 1 us jitter gt Approaches gt Ethernet IP IRT IRT gt Powerlink channel TCP IP channel TCP IP gt PROFINET prj 5 5 Cycle 1 gt Cycle 2 1 Cycle n gt gt SERCOS III gt EtherCAT e g 1 ms position control loop E Synchro nization d _ Fes February 2008 Industrial Ethernet Technologies Deterministic communication open communication Profinet IRT is a class C approach which introduces special hardware in order to achieve sufficient performance and synchronicity for motion control applications 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 250us all but one Siemens IRT master devices only support cycle times starting from 0 5 ms PROFINET V2 RT and V3 IRT Both versions can be mixed if e supported by master Modbus TCP
47. e than fast enough EtherCAT is lower costs gt Approaches gt Modbus TCP Master no dedicated plug in card co processor gt Ethernet IP on board Ethernet Port is fine Bnet gt Powerlink Slave gt PROFINET low cost Slave Controller FPGA or ASIC gt SERCOS III no powerful uC needed ABUT Infrastructure no Switches Hubs required A umman Standard Ethernet Cabling February 2008 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 EtherCAT open technology EtherCAT gt Approaches e Protocol is published completely e EtherCAT is IEC standard IEC 61158 IEC 61784 2 IEC 61800 gt Modbus TCP ISO standard ISO 15745 4 and SEMI standard E54 20 e Slave Controllers from several suppliers gt Ethernet IP e Master Stacks from several suppliers also open source e Supported by the EtherCAT oe gt Powerlink Technology Group FtherC AT Foundation November 2003 Technology Group gt PROFINET e Tasks Support Advancement and Promotion of EtherCAT e Already more than 670 member companies from gt SERCOS III 37 countries in 6 Continents Device Manufacturers End Users Technology Provider e ETG Offices in Germany USA China Japan and Korea e Membership is open to everybody gt EtherCAT gt Summary as of Jan 2008 February 2008 Industri
48. e the term Profinet IO for both approaches PROFINET Performance SA DDOACHES Communication cycle time Jitter PROFInet PROFinet PROFInet gt Modbus TCP V3 0 IRT V2 0 SRT V1 2 TCP IP gt Ethernet IP gt Powerlink c B A gt PROFINET gt SERCOS III R gt EtherCAT 5 gt Summary 0 25 1 0 10 100 msec msec msec t Depending on configuration 1 ms has been demonstrated Pictures sourced from PTO PNO website February 2008 Industrial Ethernet Technologies The cycle time range 0 25 1ms for IRT is misleading Initially most if not all IRT devices will not support cycle times lt 1 ms PROFINET V1 CbA 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 gt FEthernet IP 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 gt PROFINET a i E E gt Approaches gt Modbus TCP gt Powerlink Engineering gt SERCOS III TCP IP Ethernet TUM gt EtherCAT PROFIBUS Field device gt Summary February 2008 Industrial Ethernet Technologies 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
49. efore he can send the next request or has to wait for the timeout The response time of each slave device depends e 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 e 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 PROFINET Overview PROFINET PTO Siemens Ethernet Solution Three different varieties gt Modbus TCP Version 1 2001 Version 2 2004 CbA A RT l l l l gt Ethernet IP Component based Soft Real Time Automation Software Based l l l l l gt Approaches Version 3 2005 IRT Cc lsochronous Real Time gt Powerlink Hardware Based gt PROFINET gt SERCOS III Factory automation gt EtherCAT gt Summary IT services TCP IP Process data Real time Pictures sourced from PTO PNO website February 2008 Industrial Ethernet Technologies 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 lSochronous Real Time a Class C approach PNO tries to move away from the terms RT IRT and introduc
50. et Adoption rate as of Oct 2007 more than 6 years after publication of the spec the ODVA website lists 62 non Rockwell product guide entries 82 alltogether out of which 23 are switches cables and connectors However Rockwell ODVA started to work on this in 2006 since Profinet and EtherCAT have arrived there are lots of implementer workshops and training classes now For comparison 3 years after publication of the spec the ETG website lists 79 non Beckhoff product guide entries 112 alltogether ETHERNET MEE OUR Powerlink Overview POWERLINK gt Approaches Ethernet Approach originally introduced by B R B Medium Access Control by Polling similar to Profibus gt Modbus TCP TCP IP for Parameters seperate Process Data Protocol uses Hubs no switches e active Master Plug in Card required no Standard NICs hard realtime mode soft realtime open mode V3 initially announced for 2005 gt PROFIN ET ETHERNET ETHERNET Non deterministic Powerlink Node Powerlink Node Ethernet Node gt Ethernet IP gt Powerlink i 1i gt SERCOS III Gateway lac gt EtherCAT gt Summary en Office Factory Net February 2008 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 s
51. f Min_RPI ms Connections with 5000 gt SERCOS Ill Frames sec gt Summary February 2008 Industrial Ethernet Technologies Ethernet IP distinguishes CIP and TCP Connections Whilst most Rockwell Ethernet IP devices support up to 64 TCP connections the number of CIP connections differ from device to device 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 According to the Rockwell publication Ethernet IP Performance ENET AP001D EN P released October 2004 according to RA website still valid in January 2008 there are no Rockwell devices that support more than 32 CIP end node connections Some support more CIP connections e g for additional bridged connections that pass through the EtherNet IP module For more detailed information regarding Ethernet IP performance please check the Rockwell publication mentioned above and corresponding updates available for download on the internet There one can see also the complexity of a performance prediction for an Ethernet IP network and the need for multiple scanner cards in one controller For an example system with just 5 I O stations and two scanner cards in the host controller the maximum input delay was calculated with 32 5ms Lack of CIP connections can be a problem even in small networks one may not be able to connect a PC for configuring the PLC since this would need too many c
52. finet 1 0 E gt Summary ee ee ee ee 1000 2000 3000 4000 5000 6000 7000 announced Computed with Formulas from Ethernet Powerlink Spec V 2 0 App 3 February 2008 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 the network example used can be found in the annex of the Powerlink spec With Powerlink at this cycle time there is no remaining bandwidth for asynchronous communication For EtherCAT the Update Time 276 us is given after this period of time all outout data and all input data was transferred from or to the master an entire cycle was finished The telegram time is only 122us thus one could communicate even faster new data every 122us The Sercos lll cycle time for this example would be similar to the one of Profinet IRT J EtherCAT Synchronization EtherCAT Gao n Precise Synchronization lt lt 1 us by exact gt Modbus TCP adjustment of distributed clocks Advantage Accuracy does not depend on master precision small communication jitter and thus implementation in software only is gt Ethernet IP oles acceptable and does not deteriorate synchronization gt Powerlink gt PROFINET gt SERCOS III gt EtherCAT gt Summary February 2008 I
53. gration This does not exclude the use of TCP IP and the Internet Technologies Modbus TCP Overview Modbus IDA Schneider Electric Approach serial Modbus on TCP IP A Follows Approach A Few Services sf simple to Request from Master implement Ethernet Header Widely used IP gt Ethernet IP gt Powerlink Many Products avalabie gt PROFINET Non Real Time gt SERCOS III Approach Data Dat gt EtherCAT oe Response from Slave February 2008 Industrial Ethernet Technologies 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 a Modbus TCP Functional Principle Modbus IiDA gt Approaches e Polling Master e Each Request Response Cycle passes TCP IP Stack 4 Times e plus Switch Delays e Depending on Master Poll Request can be issued before the corresponding response has returned gt Ethernet IP gt Powerlink gt PROFINET gt SERCOS Ill gt EtherCAT
54. her devices is not yet established Slow adoption rate The Sercos Product Guide of May 2007 still online in Jan 2008 does not list Sercos lIIl products yet the only Sercos III drives seen in function on trade shows so far are by Bosch Rexroth the multi vendor demos incorporate Sercos I II drives by other manufacturers According to market survey published in August 2007 two companies supported Sercos lll drives AMK and Bosch Rexroth In a presentation held on Oct 30 2007 Sercos International lists 4 suppliers of Sercos II drives AMK Baumuller Lust Bosch Rexroth AMK Baumuller Lust have EtherCAT drives available Bosch Rexroth has announced EtherCAT drives in a press release published on Oct 5 2007 At SPS IPC Drives 2007 Elau announced to support Sercos lll By the way out of the 28 Sercos l Il servo drive suppliers that are listed in the Sercos Product guide 21 are ETG members 14 have already shown EtherCAT drives and 5 more have purchased EtherCAT implementation kits and attended implementation training classes as of Dec 2007 gt Approaches gt Modbus TCP gt Ethernet IP gt Powerlink gt PROFINET SERCOS Ill gt EtherCAT gt Summary February 2008 EtherCAT Overview Ether AT e EtherCAT is Industrial Ethernet down to the I O Level Flexible Wiring and simple Configuration lower cost well proven an open technology e Key Principle Frame Processing on the Fly
55. hernet 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 Basic Slave Device Approaches e Process Data Parallel Channel to TCP UDP IP e TCP UDP IP Timing Controlled by Process Data Driver e Ordinary Ethernet Controllers and Switches or Hubs gt Modbus TCP Principle applied by gt Ethernet IP Parameter Process ETHERNET Sill oom PO ER Data fl Data gt Powerlink Software Layer 5 7 gt PROFINET avers TCP UDP Layer 4 eens Protocol gt SERCOS III Layer 3 TRE Layer 1 2 Ordinary Ethernet Controller Slave Device Architecture gt EtherCAT Hardware gt Summary February 2008 Industrial Ethernet Technologies Class B approaches still use s
56. iders that EtherCAT is even at twice the cycle time still faster than any other solution gt Approaches gt Modbus TCP gt Ethernet IP gt Powerlink gt PROFINET SERCOS Ill gt EtherCAT gt Summary February 2008 EtherCAT Summary EtherCAT e 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 e EtherCAT is Open technology worldwide supported IEC standard Low cost and simple to implement SERCOS interface is a trademark of SI e V 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 gt Approaches gt Modbus TCP gt Ethernet IP Cycle Time gt Powerlink gt PROFINET mie e gt SERCOS III Synchronicity gt EtherCAT CIP sync Throughput tt t O duplex February 2008 Industrial Ethernet Technologies In principle one should not compare technologies in such an overview table since the ratings are
57. ince 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 uC 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 EtherCAT Performance Example EtherCAT e 40 Axis each 20 Byte Input and Output Data e 50 I O Station with a total of 560 EtherCAT Bus Terminals gt Modbus TCP e 2000 Digital 200 Analog I O Bus Length 500 m e Performance EtherCAT Cycle Time 276s Sehenmenic at 44 Bus Load Telegram Length 122us e For comparison Sercos lll 479 us Profinet IRT 763 us Powerlink V2 2347s Profinet RT 6355 us gt Approaches gt Powerlink EtherCaT gt PROFINET Sercos Ill gt SERCOS III Profinet IRT lf Powerlink Gbit gt EtherCAT Powerlink E Pro
58. inet I O and EtherCAT are proven technologies just as Powerlink V1 and unlike Powerlink V2 First version of Profinet IRT started to ship in 2006 new version with new ASICs expected for 2009 There are few published IRT pilot applications and according to my best knowledge most use a Siemens only protocol variant First Sercos lll 1 0 devices start shipping in 2006 so far very few applications in 4 2007 less than 1000 device were shipped New enhanced V1 1 version incompatible with V1 started shipping in December 2007 International Standardization As far as international standardization is concerned all listed technologies can be considered to be even Since Oct 2007 all are part of IEC 61158 and IEC 61784 2 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 Sercos lll CPF 16 IEC 61158 Type 19 EtherCAT CPF 12 IEC 61158 Type 12 gt Approaches gt Modbus TCP gt Ethernet IP gt Powerlink gt PROFINET gt SERCOS IlI gt EtherCAT February 2008 Industrial Ethernet Technologies
59. k will be slower than 100MBit Powerlink In addition announcing GBit Powerlink further confuses the potential implementers should he implement V1 V2 or wait for Gbit Furthermore chips in Gbit mode draw much more power which would be a problem for many automation devices ETHERNET Si mI E Gigabit Powerlink 10 x faster POWERLINK Ethernet Powerlink V2 0 gt Approaches Performance Example 4 from eee cae ae he Powerlink Specification V2 r ni Process Data Communication only gt Modbus TCP no bandwidth for acyclic communication y Example 4 Hubs no Switches n this example are BO Controtied Hodes 40 dris gt Ethernet IP Cycle Time with 100 MBit s 2 39 ms Cycle Time with 1 Gbit s 1 45 ms gt Powerlink Performance Gain Factor 1 64 gt PROFINET For Example EtherCAT Cycle Time SERCOS Ill 44 Bus load 0 28 ms gt EtherCAT gt Summary February 2008 Industrial Ethernet Technologies In November 2006 EPSG announced Gbit Powerlink claiming the network performance would be 10 times 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 Doing the maths shows that the performance gain would be minimal Depending on th
60. ket POWERLINK gt Approaches Network Feature Availability Version gt Modbus TCP Powerlink e Protected mode Available by B amp R Version 1 only gt Ethernet IP Powerlink e Enhanced initialization Spec Q4 2003 Version 2 e Configurable e First gt Powerlink asynchronous channel prototypes e Complete TCP IP HMI 2004 PROFINET implementation No Pilot Bridge Router Support applications gt SERCOS III published yet Not compatible gt EtherCAT to version 1 Powerlink e Open mode End of 2005 gt Summary Version 3 e EEE1588 synchronization February 2008 Industrial Ethernet Technologies Powerlink Version 1 products are available from B amp R only Powerlink Version 2 Prototypes were announced for Hannover Fair 2004 but the multi vendor demo was based on V1 prototypes Those prototypes were not advanced to become V1 products In an interview in April 2006 B amp R claimed that they were shipping V2 devices since beginning of 2006 which proves my point that the devices in the field are V1 As of July 2006 none of the B amp R applications with V2 has been published yet According to well informed sources in April 2007 B amp R was still shipping V1 devices only and is thus incompatible with any product developed by other EPSG member companies At Hannover Fair 2006 Lenze Drives founding member of Ethernet Powerlink Standardization Group and driving force behind V2 has announced first Powerlink Products fo
61. le The slaves process the data twice on the way out and on the way back IP data is inserted in gaps between the frames Very rigid frame layout no changes at runtime no bit wise mapping These differences have the following impact compared with EtherCAT 1 Bandwidth utilization is lower especially for drives which typically have symmetrical process images Same amount of I O data Therefore in average 2 3 times slower than EtherCAT Separating input and output data and processing twice allows for topology independent slave to slave communication within the same cycle However since the cycle time is higher slave to slave performance is not better than with EtherCAT which may need two cycles depending on topology Since gaps for maximum size frames have to be kept even if there is no IP communication present which is the case in gt 99 99 of the cycles since IP is not used for cyclic communication this further deteriorates bandwidth usage Due to the processing twice principle only line topology ring for redundancy are possible no drop lines tree configuration etc No flexibility in process data communication same update rate for all nodes and data SERCOS Ill Synchronization II SERCOS interface gt Approaches media layer MAC layer Data fleld will be padded gt Modbus TCP SI 11 1 Byte f 1 Byte 6 Byte b Byte Byte 4 yie 40 1494 Hytte 4 Byte 1 Byte gt Ether
62. n scenarios line gt Ethernet IP structure 50 nodes lt 60Bytes cyclic data per node EtherCAT is substantially faster than Profinet IRT gt Powerlink e According to the PNO Profinet IRT is faster if gt PROFINET the average payload per node exceeds 60 Bytes gt SERCOS III e However some features of EtherCAT such as gt EtherCAT full duplex frame usage and pipelining of frames gt Summary were not considered February 2008 Industrial Ethernet Technologies Within the research project ESANA funded by the German Federal Ministry of Education and Research Siemens Phoenix Contact and some other parties are looking for performance enhancement possibilities for Profinet This is remarkable since it documents that in PNO Siemens Phoenix view 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
63. ndustrial 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 lt lt 1us f EtherCAT is Industrial Ethernet EthercAT gt Approaches e EtherCAT only Standard Ethernet Frames IEEE 802 3 e Master Ethernet MAC without co processor or special HW Modbus TCP e Fully transparent for other Ethernet protocols e Internet Technologies TCP IP FTP Web server etc without restricting the real time capabilities even with 100uUs cycle time no large time gaps for rare traffic needed e Full Tool Access to devices at real time operation with and without TCP IP gt Ethernet IP gt Powerlink gt PROFINET gt SERCOS III 48 Bit 48 Bit 16 Bit 16 Bit Destination Source EtherType Hea gt EtherCAT Embedded in Standard nem o gt Frame EtherType
64. net IP a eae y checked via FCS Lal gt Powerlink i telegram length 72 1526 Byte overhead 2646 32 Byte telegram time 5 ps 122 1ips i E MI data isd i i gt PROFINET telegram length 64 1538 Byte overhead 3446 44 Byte telegram tine 6 0 123 Ips I gt SERCOS III Synchronization Trigger gt EtherCAT gt Summary Synchronization Accuracy depends on Master Accuracy hardware support required Source Presentation at Automation Summit Beijing June 2007 February 2008 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 gt Approaches gt Modbus TCP gt Ethernet IP gt Powerlink gt PROFINET gt SERCOS Ill gt EtherCAT gt Summary February 2008 SERCOS Ill Synchronization II SERCOS an q 4 u m Iz u mm interface SERCOS Ill Master PERIA Ehornet Daia using Standard Ethernet a Contralor e wr Hardware LL u Ei j NEW A ot _ Real Time Operating Systom of Control System SERCOS Ill Master mel seRcoN ow with passive SERCOS III 2 hjen E SERCOS Ill Master with active SERCOS III interface board Announced in April 2007 Soft Master suitable if RTO
65. ntegrated hubs Powerlink or special switches Profinet IRT are sufficient if not external hubs or special switches are required Sercos Ill and EtherCAT do not require switches or any other active infrastructure components gt Approaches ModbustOA py Strategic Modbus Ethernet ProfiNet gt Modbus TCP Topics I TCP NP RT VO gt Ethernet IP Size of supporting gt Powerlink organization gt PROFINET Worldwide User Group gt SERCOS III gt EtherCAT v1 new IRT Version in gt Summary 2009 Not all ODVA or PTO PNO members support Ethernet February 2008 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 October 2007 the EtherCAT Technology Group has 607 member companies Sercos International has 40 member companies EPSG Powerlink has 66 member companies ODVA has 297 member companies PTO is much larger but their membership is predominantly fieldbus Profibus related ModbusTCP is so widely used that the Modbus IDA membership of 55 members only does not reflect its acceptance Worldwide User Group ODVA and PTO are present worldwide as is ETG with offices in Europe North America China and Japan Time to Market Modbus TCP is available since 1999 Ethernet IP since 2001 Profinet RT has entered the market in 2005 Powerlink V2 is not yet widely available the B amp R proprie
66. only IRT switches are used e enough bandwidth available gt Approaches gt Ethernet IP IRT Standard IRT Standard IRT channel channel channel channel channel 1 a es os os gt PROFINET _ Cycle1 gt Cycle2 Cycle 1 time window e g 2 ms position control loop gt Powerlink gt SERCOS III isochronous RT Standard communication communication communication _ oe Lee Eu IRT Data RT Data Se a gt Summary February 2008 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 PROFINET IRT System Planning I gt Approaches Input for planning configuration of the network e the topology of the network e and for every transmission e the source and the target node e the amount of transmission data e projected features of the connection path e g Redundancy gt Modbus TCP gt Ethernet IP gt Powerlink Output of the projection for every transmission and switch e Ports and exact transfer time timing for each frame gt SERCOS III gt EtherCAT gt Summary February 2008 Industrial Ethernet Technologies Besides hardware costs the crucial issue of Profinet IRT is the complex system planning PROFINET IRT System Planning Il AD
67. onnections In November 2006 RA announced a new generation of Ethernet IP scanners which will support up to 10 000 frames second With these new scanners the cycle times in the table above will be half as long and thus system real time performance will remain relatively poor However the latest release notes Publication 1756 RN591P EN P June 2007 of the Contrologix Ethernet IP Bridge 1756 ENBT 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 f Ethernet IP CIP Sync Eike Aom A CIP Sync gt gt Approaches Ethernet IP has limited Real Time Capabilities limited Cycle Time Performance limited Determinism gt Modbus TCP acceptable Throughput for large Data Units e CIP Sync will add Time Synchronisation gt Ethernet IP e Distributed Clock Protocol IEEE 1588 gt Powerlink e CIP Sync announced April 2003 Added to CIP spec in May 2006 Version 3 0 First products expected for 2008 gt PROFINET gt SERCOS Ill gt EtherCAT gt Summary February 2008 Industrial Ethernet Technologies CIP sync was introduced to improve the real time behavior of the system The marketing message given by ODVA tries
68. ous industries and leading automation suppliers join forces to support promote and advance the EtherCAT technology With over 650 members the EtherCAT Technology Group has become the largest organization in the world that is exclusively focused on Industrial Ethernet technologies Founded in November 2003 it is also currently the fastest growing fieldbus organization EtherCAT versatile System EtherCAT e Master to Slave Slave to Slave Master to Master e Transparent tool access to all nodes gt Modbus TCP e open interfaces gt Approaches gt Ethernet IP gt Powerlink gt PROFINET SERCOS Ill gt EtherCAT gt Summary February 2008 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 cons
69. r End of 2006 At the same show Lenze has announced EtherCAT drives ETHERNET i mi E Powerlink Versions POWERLINK gt Approaches ETHERNET gt Modbus TCP OW SOE Version 1 available gt Ethernet IP Protected mode gt 15 000 nodes deployed in serial machinery Ae e Version 2 Dec 2003 owenin CANopen integration Enhanced initialisation gt PROFINET Configurable asynchronous slot Full TCP IP support Routing gt SERCOS III Securi First products at Hannover Messe i Version 3 2004 gt EtherCAT Open mode IEEE 1588 gt Summary Source Powerlink Seminar Proceedings Stuttgart 16 6 2004 EPSG website February 2008 Industrial Ethernet Technologies This slide found at the EPSG website in 2004 shows the Roadmap and proves that the first nodes shipped in quantities were Version 1 Version 3 was postponed meanwhile Powerlink gt Approaches gt Modbus TCP gt Ethernet IP gt Powerlink gt PROFINET gt SERCOS III gt EtherCAT gt Summary new in Version 2 What s New in ETHERNET Powerlink V2 ad ETHERNET Configuration Manager Application Trane port Source Powerlink Seminar Proceedings Stuttgart 16 6 2004 EPSG website February 2008 Industrial Ethernet Technologies It is important to distinguish between Powerlink Version 1 and Version 2 since both versions have little in common both use half duplex hub technology
70. rames to the next cycle e Cut Through Switches can only forward frame within same cycle if gt 125us IP channel is left since frame length is unknown e IP channel performance strongly depends on No of Nodes IP gt EtherCAT channel size and slave controller implementation gt Summary February 2008 Industrial Ethernet Technologies 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 SERCOS III V1 1 II SERCOS interface gt Approaches e In July 2007 SERCOS International released the 1 1 version of the SERCOS III specification gt Modbus TCP e Main changes are Device addressing changed now topology dependent gt FEthernet IP Parameter addressing changed from 16 bit IDN to 32 bit structured EIDN status control word format and content changed Powerlink Redundancy and hot plug features introduced Communication model changed from master slave to connection oriented 511 instead of 254 slave devices supported PROFINET Mandatory IP channel introduced Interrupt handling changed now one Sync IRQ gt SERCOS III e The specification changes require hardware adaptations Sercos controllers and also major software changes ATEN e Version 1 0 and Version 1 1 devices are not interoperable
71. rding to EPSG news one company Yacoub Automation joined EPSG at SPS IPC Drives in Nov 2007 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 The EPSG website e g lists Tetra Pak in the members and users list According to a Tetra Pak R amp D manager they used Powerlink in one R amp D project which was later cancelled never delivered a Powerlink equipped system and also terminated their EPSG membership ETHERNET MEE OUR Powerlink Summary POWERLINK e Polling over Ethernet All Frames are broadcasted gt Modbus TCP e Cycle times similar to SERCOS II e Performance difficult to predict depends on selected SEineRnenie devices and on topology e Requires protected network segment gt Powerlink e Requires substantial processing power master slave or implementation in hardware e g FPGA gt Approaches gt PROFINET e Based on outdated half duplex Hub technology gt SERCOS III e Limited no of nodes can be connected in line topology e requires Master with dedicated Communication processor EtherCAT no Commercially of the Shelf COTS Network interface card NIC gt Summary e Version 2 is not field proven yet e Version 2 is not downwards compatible February 2008 Industrial Ethernet Technologies Due to the polling principle the master has to wait for the response of each slave b
72. switches with IGMP support Hubs with 100 MBit s Powerlink cannot be considered COTS technology since the chips are obsolete Profinet IRT requires special switches throughout sercos lll 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 gt Approaches Features gt Modbus TCP gt Ethernet IP Slave to Slave gt Powerlink TCP IP amp other Internet Technologies r ted gt PROFINET S T oe Switches Cable with gt SERCOS Ill Redundancy sam e tree gt EtherCAT algorithm extremely complex no known approach February 2008 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 cycles so performance of this communication type may be degraded to Sercos lll or Profinet IRT levels TCP IP amp other Internet Technologies supported 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 Sercos lll connect generic Ethernet devices e g Service notebooks via Gateways Profinet IR
73. t IP Improved Framestructure gt Powenink Same Structure Offsets for all frametypes Header Mie he CRC 14 4 gt PROFINET New Device Type Async only CN Polled by MN via IdentRequest No PReq PRes Polling for this node gt No Process Data PDO gt SERCOS III gt EtherCAT gt Summary Source Powerlink Seminar Proceedings Stuttgart 16 6 2004 EPSG website February 2008 Industrial Ethernet Technologies The frame structure was changed from V1 to V2 and is thus incompatible Powerlink new in Version 2 What s New in Even the Cycle was ETHERNET Powerlink V2 changed Introduction ETHERNET Approaches of Asynchronous Slot ae gt Modbus TCP ETHERNET aoe GROW gt Ethernet IP EOC Invite gt Start of Asynchronous SoA gt Support of IP Telegrams in Asynchronous slot gt Powerlink gt Timing configurable Devices with lower performance can be supported gt PROFINET PRes send as Multicast gt Easy filtering possible PRes send by MN gt SERCOS III gt EtherCAT soc oa gt Summary Gentoted Nodes TH Source Powerlink Seminar Proceedings Stuttgart 16 6 2004 EPSG website February 2008 Industrial Ethernet Technologies The cyclic behavior of the network was changed as well ETHERNET Si mi EE Gigabit Powerlink 10 x faster POWERLINK Eth t P rlink V2 0 gt Approaches Performance Example 2 from E MENE Powerlink Specification V2 aiiai
74. t IRT gt Powerlink Version Profinet V4 which requires new ASICs gt PROFINET was announced e The new ASICs are gt SERCOS III expected in 2009 In October 07 the price errs eet for the old ASICs was e Main Line with k 8 nodes in each bus Cycle reduced by 40 3 5 5 Drop lines with n 10 nodes in each 8th Cycle e Distance between nodes 50m gt Summary February 2008 Industrial Ethernet Technologies PNO intends to show a Profinet V4 demonstrator in April 2008 at Hannover Fair ASICs supporting this version will be available in 2009 According to Siemens statements the new ASICs will not support Gigabit 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 e 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 e The PNO analysis shows clearly that in typical application scenarios EtherCAT is much faster than the fastest Profinet variant IRT class 3 e 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 EtherCA
75. t predefined timing for each connection Low priority communication is handled in the NRT time slice This improves the network performance in case of mixed communication if the application has NRT traffic such as TCP IP but does not guarantee synchronous real time behavior under all circumstances 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 Main application field for RT class 2 are PLC type applications but network performance should also be sufficient for small motion control applications RT Class 3 also called IRT TOP is the variant formerly referred to as Profinet IRT This approach provides hard real time behavior but requires the detailed network planning and the optimization algorithm PTO PNO generally downplays the differences between the Profinet variants Summarizing all of them with the term Profinet IO gt Approaches C Hardware assisted Profinet ae Profinet IRT gt Modbus TCP RT Class 2 RT Class 3 time slicing without with topology oriented gt Ethernet IP topology planning network planning defined timing for POA Soft Real Time with each connection path Hardware Support Hard Real Time gt PROFINET gt SERCOS III gt EtherCAT gt Summary Motion Applications 9 J v4 d Ey A W AA A February 2008 Industrial Ethernet Technologies
76. tandard 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 J a Basic Slave Device Approaches e Process Data Parallel Channel to TCP UDP IP e TCP UDP IP Timing Controlled by Process Data Driver e Special Realtime Ethernet Controllers or Switches gt Modbus TCP Principle applied by gt Ethernet IP PIRIOIF i Parameter Process ANTENT 3 Data Data gt Powerlink IRT a L Dal J ERCOS mace lt m gt PROFINET fl interface ey En gt SERCOS III EtherCAT aeS iming Layer Layer 1 2 Special Realtime Ethernet Controller co oO E ep Process Data Protocol gt EtherCAT Slave Device Architecture Hardware gt Summary February 2008 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 inte
77. tary version 1 is shipping since end of 2002 The next generation Profinet IRT chips are expected for 2009 first sercos lll V1 1 devices were shipped end of 2007 EtherCAT is used in series applications since end of 2003 according to website www sercos de as of Oct 2007 12 Sercos North America 15 Sercos Japan according to EPSG Publication PowerlinkKFACTS published in November 2007 In April 2007 there were 71 member companies according to www odva org as of Oct 2007 according to www modbus ida org as of Oct 2007 gt RTE Technology Comparison gt Approaches Strategic gt Modbus TCP Uglies Uy gt Ethernet IP Special O Hardware gt Powerlink used a M S CIP ee FPGA gt PROFINET Proof of gt SERCOS III Technology z Pilot m Applications CIP v2 gt EtherCAT Sync ua gt Summary International Standardization February 2008 Industrial Ethernet Technologies Special Hardware Used Modbus TCP Ethernet IP not ClPsync Profinet I O 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 and Sercos lll requires 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 Proof of Technology Pilot Applications Modbus TCP has been used for many years Ethernet IP Prof
78. though closing control loop over bus system will be part of spec limited gt SERCOS III performance of Ethernet IP leads to trajectory generator in drive e Same approach as with legacy non motion gt Summary fieldbus systems gt PROFINET gt EtherCAT Etherhetif February 2008 Industrial Ethernet Technologies 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 insure 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 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
79. witches 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 gt 10us for short frames cut through switches have a delay time according to Intel of 7 ous If hubs were replaced by switches with 10us 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 ETHERNET MEE OWE Powerlink Functional Principle POWERLINK gt Approaches e Polling Marketing Time Slice Modbus TCP e Hubs only half duplex e Broadcast every node receives every frame e Thus high Interrupt load and processing requirements e
80. with ClPsync Ethernet IP CIP Sync nen ip gyno gt Best suited and typically used as Controller to Controller network Modbus TCP e Limited No of Connections e Bus cycle time is typically 5 10 ms e Reaction time is typically 15 30 ms e Determinism is added via system time synchronized actions and gt Powerlink timely non deterministic communication gt Approaches gt Controller a EtherNet IP gt gt sae 7 gt PROFINET o gt warns gt SERCOS Ill T ontroller gt gt EtherCAT gt S Controller ummary ControlNet Example Ethernet IP Network February 2008 Industrial Ethernet Technologies 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 CIPsync are suitable for synchronizing motion controllers but the communication performance is not sufficient for closed loop servo drive communication Fh CIP Motion CIP Syne Sy P Sn Initiative of ODVA to enhance CIP networks for motion control gt Approaches Modbus TCP Ethernet IP Premise Full duplex switched Ethernet with QoS Prioritization IEEE 1588 Synchronization and time stamped data gt FEthernet IP transmission is deterministic enough for motion control Motion Control Device Profiles included in V3 of CIP Spec gt Powerlink First products expected for 2008 Even
81. y in Aachen Germany ad e In 2007 EPSG Office moved to U ETHERNET i OP at advertising agency in Berlin Germany POWERLINK Powerlink e 2007 New Logo and Cl gt Powerlink e Recent Membership gt PROFINET Development from 69 members in 5 2006 to 71 members in 11 2006 to gt SERCOS Ill 71 members in 4 2007 to a 65 members in 11 2007 i EPSG gt EtherCAT Membership Development gt Approaches gt Modbus TCP gt Ethernet IP gt Summary Mai 06 Aug 06 Nov06 Feb07 Mai07 Aug 07 Nov 07 Source Powerlink Facts May Nov 2006 April Nov 2007 published by EPSG EPSG website February 2008 Industrial Ethernet Technologies Ethernet Powerlink Standardization Group is managed and hosted by an advertising agency Technical and implementation support is available by technology providers only who charge for these services ETG acknowledges that 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 brackets Between 5 2006 and 11 2007 ETG grew from 315 to 634 members reaching 670 members on January 15 2008 The figures discussed above were taken from the EPSG publication Powerlink Facts which is available for download from the EPSG website There all members are listed Acco

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