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Unmodified Ethernet for Industrial Automation? Unmodified Ethernet for Industrial Automation? • Benefits of Ethernet for Automation • Ethernet Features – an Overview • Limiting Factors of Ethernet as Fieldbus Replacement SUE: Standard Unmodified Ethernet Fieldbus Foundation High Speed Ethernet (HSE): What are the benefits of HSE? ….Use of unmodified Ethernet and standard IP makes HSE systems more cost-effective than other Ethernet solutions and proprietary networks…. © EtherCAT Technology Group Benefits of Ethernet for Automation • Ethernet is in use for Controller/Controller communication since many years, as it saves money to use commodity technologies: Examples: • CAN (originally developed for automotive applications) • PC-based Controls • Windows + Linux • So Automation benefits from the much larger IT Communication • Thus low cost hard- and software • If also on Fieldbus ( I/O, Sensor and Drives) Level: just one communication technology remaining • Improvement also financed (and driven !) by others © EtherCAT Technology Group Ethernet Overview: CSMA/CD, TCP/IP & others • Architecture • Physical Layer: Signal, Cables + Wiring • Media Access Control • Name Resolution • Routing • IP, TCP + UDP This diagram was hand drawn by Robert M. Metcalfe and photographed by Dave R. Boggs in 1976 to produce a 35mm slide used to present Ethernet to the National Computer Conference in June of that year. © EtherCAT Technology Group Ethernet Definition (Wikipedia) Ethernet is a frame-based computer networking technology for local area networks (LANs). It defines wiring and signaling for the physical layer, and frame formats and protocols for the media access control (MAC)/data link layer and a common addressing format Ethernet is standardized as IEEE 802.3. It has become the most widespread LAN technology in use during the 1990s to the present, and has largely replaced all other LAN standards such as token ring, FDDI, and ARCNET. © EtherCAT Technology Group ISO/OSI, IEEE 802 and TCP/IP ISO/OSI - Model TCP/IP - Model 7 Application Layer 5 Application Layer: contains a variety of commonly used protocols, such as file HTTP, FTP, rlogin, Telnet, DHCP,... transfer, virtual terminal, and email 6 Presentation Layer manages the syntax and semantics of the information transmitted between two computers 5 Session Layer establishes and manages sessions, conversions, or dialogues between two computers 4 Transport Layer 4 Transport Layer: TCP + UDP splits data from the session layer into smaller packets for Handles communication among programs on a network. delivery on the network layer and ensures that the packets arrive correctly at the other end 3 Network Layer 3 Network Layer: IP (Internet Protocol), controls the operation of a packet transmitted from one network This layer is used for basic communication, addressing and routing. to another, such as how to route a packet. 2 Data Link Layer 1/2 Medium Access Control (MAC) transforms a stream of raw bits (0s and 1s) from the physical IEEE 802.3: CSMA/CD (Ethernet), 802.4 Token Bus (ARCnet), 802.5 Token layer into an error-free data frame (packets) for the network layer Ring, 802.11 Wireless, 1 Physical Layer Cables, cards and physical aspects: ISO/IEC 11801, parts also in IEEE 802.3 transmits signals across a communication medium © EtherCAT Technology Group Ethernet Transmission Media (IEEE802) 1BASE5 UTP 10GBASE-W W PCS/PMA overundefined PMD 10BASE2 Coax 10GBASE-EW W fibreover 1550nm optics 10BASE5 Coax 10GBASE-LW W fibreover 1310nm optics 10BROAD36 Coax 10GBASE-SW W fibreover 850nm optics 10BASE-T UTP, duplex mode unknown 10GBASE-KR Backplane Ethernet (802.3ap, 2007) 10BASE-THD UTP, half duplex mode 10GBASE-KX4 Backplane Ethernet (802.3ap, 2007) 10BASE-TFD UTP, fullduplex mode 10GBASE-LRM multimode Fibre (802.3aq, 2006) 10BASE-FP Passive fiber 10GBASE-T UTP (802.3an, 2006) 10BASE-FB Synchronous fiber 40GBASE-SR4 Multimode Fibre, 100m (802.3ba,2010) 10BASE-FL Asynchronous fiber 40GBASE-LR4 Singlemode Fibre, 10km (802.3ba,2010) 100BASE-T2 Two-pair Category 3 UTP 40GBASE-CR4 Copper Cable Assembly, 10m (802.3ba,2010) 100BASE-T4 Four-pair Category 3 UTP 40GBASE-KR4 Backplane Ethernet (802.3ba,2010) 100BASE-TX Two-pair Category5 UTP 100GBASE-SR10 Multimode Fibre, 100m (802.3ba,2010) 100BASE-FX Two-strand Multimode Fibre 100GBASE-LR4 Singlemode Fibre, 10km (802.3ba,2010) 100BASE-VG Four-Pair Category 3 UTP 100GBASE-ER4 Singlemode Fibre, 40km (802.3ba,2010) 1000BASE-T Four-pair Category 5 UTP PHY 100GBASE-CR10 Copper Cable Assembly, 10m (802.3ba,2010) 1000BASE-T X Four-pair Category 6 UTP PHY 1000BASE-LX Multimode Fibre 1000BASE-SX Multimode Fibreor Singlemode Fibre Large variety of physical layers 1000BASE-CX X copper over 150-Ohm balanced cable PMD 1000BASE-BX10 Bidirectional single strand Singlemode Fibre 1000BASE-LX10 Two-strand Singlemode Fibre 1000BASE-PX10 -D Singlemode Fibre, Downstream, 10km 1000BASE-PX10 -U Singlemode Fibre, Upstream, 10km 1000BASE-PX20 -D Singlemode Fibre, Downstream, 20km 1000BASE-PX20 -U Singlemode Fibre, Upstream, 20km 1000BASE-KX 1m overBackplane 10GBASE-X X PCS/PMA overundefined PMD 10GBASE-LX4 X fibreover 4 lane1310nm optics 10GBASE-CX4 X copper over 8 pair 100-Ohm balanced cable, 15m 10GBASE-R R PCS/PMA overundefined PMD 10GBASE-ER R fibre over 1550nm optics 10GBASE-LR R fibre over 1310nm optics 10GBASE-SR R fibreover 850nm optics © EtherCAT Technology Group Cabling Standards (Copper) 100 MHz 250 MHz 500 MHz 600 MHz 1000 MHz 1200 MHz TIA/EIA TIA/EIA TIA/EIA TIA/EIA TIA/EIA TIA/EIA 568 B.1/2 568 B.2-1 568 B.2-10 568 B.2 568 B.2 568 B.2 Cat. 5e Cat. 6 Cat. 6a Cat. 7 Cat. 7a Cat. 8 ISO/IEC ISO/IEC ISO/IEC ISO/IEC ISO/IEC ISO/IEC 11801: 11801: 11801: 11801: 11801: 11801: Class D Class E Class EA Class F Class FA Class G CENELEC CENELEC CENELEC CENELEC EN50173-1 EN50173-1 EN50173-1 EN50173-1 Class D Class E Class F Class G IEEE 802.3 IEEE 802.3 IEEE 802.3 100BASE-TX 10GBASE-T 10GBASE-T 1000BASE-T (55m) (100m) © EtherCAT Technology Group Two or Four Pairs? 100BASE-TX 1000BASE-T two pairs: four pairs: • one pair sends • all four pairs send and receive simultaneously • one pair receives • Encoding: PAM-5 – TCM • Encoding: 4B5B – MLT-3 5-level Pulse Amplitude (PAM-5) with Multilevel Transmission Encoding Trellis Coded Modulation (TCM) Tx Rx Rx/ Rx/ Tx Tx Rx/ Rx Tx Rx/ Tx Tx Rx/ Tx Rx Rx/ Tx Tx Rx/ Rx/ Rx Tx Tx Tx © EtherCAT Technology Group IEEE 802.3: Media Access Control CSMA/CD „Carrier-Sense Multiple-Access with Collision-Detection“ – The node that wants to send checks if the media is available „Carrier-Sense“ – All nodes are equal and may send autonomously „Multiple-Access“ – The sender checks after sending if there was a collision „Collision-Detection“ – maximum Ethernet propagation delay: 25,6µs (@10MBit/s) (determined by cable length & repeater delays) Start Transmission Carrier Sense undisturbed Transmission Collision Window © EtherCAT Technology Group Media Access Control CSMA/CD Node A Node B Carrier Signal Propagation Delay Sense Node A Node B Multiple A starts sending Access / Node A Node B Collision B starts sending Detection Node ACollision Node B © EtherCAT Technology Group Ethernet Collision Domain Hub B Hub • Hubs • half duplex • Hub Cascading & Length limited A © EtherCAT Technology Group Switched Ethernet Topology Switch B • Switches Switch • full duplex full duplex communication Switch sends Queues avoid single cast collisions communication only to the destination port A © EtherCAT Technology Group „Store and Forward“ vs. „Cut-Through“ Most Switches use the „Store and Forward“ principle: • Receive entire frame first, check FCS, then forward to destination port. • Advantage: only „healthy“ frames are forwarded. • Disadvantage: large and variable forwarding delay (ca. 10…125 µs, depending on frame length –the buffer delay comes on top) Preamble SFD DA SA LEN DATA Pad FCS Only very few Switches make use of the „Cut-Through“ principle: • Frames are forwarded shortly after receiving the destination address. • Advantage: shorter delay (ca. 5…7 µs) • Disadvantage: corrupted frames are forwarded as well Preamble SFD DA SA LEN DATA Pad FCS © EtherCAT Technology Group Ethernet Packet 7 1 6 6 2 46-1500 0-46 4 Byte Preamble SFD DA SA LEN DATA Pad FCS Length Data „Payload“ Frame Check Sequence (CRC) Sender Address Padding Field Destination Address Start Frame Delimiter „10101011“ Preamble „1010101010.....“ used for Bit Synchronisation • The Length Byte has two meanings: if it is >0x5DC then it describes the type of the „payload“ (Ethertype. e.g. IP 0x0800 or ARP 0x0806 or EtherCAT 0x88A4) • If the data length is <46 Byte, Padding Bytes are introduced to achieve a minimum length of 46 Bytes (for collision detection) © EtherCAT Technology Group Ethernet MAC-ID „Medium Access Control Address“ (MAC-ID) has to be unique • Two Fields of 3 Bytes: – 1. OUI (Organizationally Unique Identifier) – 2. Serial Number • The OUI is assigned by the IEEE Standards Department (USA) • e.g. Beckhoff OUI : 0x00 01 05 http://standards.ieee.org/ develop/regauth/oui/ public.html Result from http://standards.ieee.org/cgi-bin/ouisearch © EtherCAT Technology Group Addressing: MAC-ID, IP Address, Host Name • Structure allows one to exchange protocol layers Host Name Host (DNS/DHCP/ Resolution Name HTTP/FTP) „CX_001387“ TCP-Header (IP-Port) TCP Address 21 (FTP), 80 (HTTP) Resolution IP-Header Internet Protocol (IP) (IP-Address) PROT 169.254.254.88 Ethernet-Header (MAC-ID) Ethernet 08-00 00 01 05 00 13 87 © EtherCAT Technology Group Host Name Resolution: Domain Name Service Working Principle 1. Entry in Cache of the DNS Server? authorative 2.
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