Slide 1 Ethernet Evolution - Switching  Switched Ethernet with full duplex communication  Now there are no collision domains and hence no collisions! F1 F6 F2 F7 F3 F8 F4 F9 F5 F1

Slide 2  Original Ethernet standards  Maximum frame size – 1518 bytes  Recent change to allow Prioritisation  Maximum frame size – 1522 bytes (increase of 4 bytes) Ethernet Evolution – Prioritisation (QoS) PreambleSFD Destination- Address Source Address FCSData Length/ Type PreambleSFD Destination- Address Source Address FCSData Length/ Type TAG TPIDTCI TPID = Tag Protocol Identifier TCI = Tag Control Information CFI = Canonical Format Indicator Tag Protocol ID User Priority CFIVLAN ID 16 bit3 bit1 bit12 bit 64 byte byte

Slide 3 Ethernet Evolution – Prioritisation (QoS) File Video Voice + Attach Voice Video File Priority

Slide 4 Ethernet Evolution - VLANs  Part of the same development as Prioritisation was VLANs or Virtual Local Area Networks.  DTE can be tagged as belonging to a virtual LAN.  Any traffic for something outside of that VLAN will not be accepted by the DTE.  Switches too can monitor VLAN traffic and will not pass on frames that are not for that VLAN.

Slide 5 SCADA Server Sales Server IT Server Manufacturing Sales IT Ethernet Evolution - VLANs

Slide 6 Ethernet Evolution - Redundancy  Spanning Tree? No, Industrial Redundancy! ab Windows NT, 2000 etc

Slide 7 Bringing it all together  By combining all the recent developments of Ethernet together, data throughput is greatly increased. 10Mbit/s shared 10Mbit/s switched full duplex 100Mbit/s switched 10Mbit/s switched 100Mbit/s shared 100Mbit/s switched full duplex 4Mbit/s 10Mbit/s 20Mbit/s 200Mbit/s 40Mbit/s 100Mbit/s

Slide 8 Real-Time Ethernet  So is Ethernet a real-time control network?  Consider our original definition of real-time  Adjective :(computer science) of a system, in which data- processing occurs as the data is generated.  No, Ethernet cannot be considered a real-time control network, a control network definitely, but not a real-time one.  BUT, what about a deterministic one??

Slide 9 Deterministic Ethernet  Consider this typical RS485 bus network

Slide 10 M=Master; S= Slave; SW= Switch RS1 Application with one Master, 31 Slaves and 4 RS1-Switches 100 Mbit/s MS7S8 SW1SW2SW3SW4 S1 S8S15S16S23S24S31 10 Mbit/s M Cascading of 10/100 Switches

Slide 11 Multicast from Master to all Slaves: Send packet from Master to SW1: 57.6µs Latency in SW1: 4.0µs Receive packet in Slave 1: 57.6µs Send packet S1 to SW2: 5.76µs Transmit time SW1 to SW2 : 2.5µs Latency in SW2: 4.0µs Send packet SW2 to SW3: 5.76µs Transmit time SW2 to SW3 2.5µs Latency in SW3: 4.0µs Send packet SW3 to SW4: 5.76µs Transmit time SW3 to SW4 2.5µs Latency in SW4: 4.0µs Receive packet in Slave 31: 57.6µs Total time: µs Receive packet at slave 1 Receive packet at slave 31 This time is called: Receive variance Cascading of 10/100 Switches

Slide 12 All Slaves sending response to Master: Send packet Slaves to SW4: 57.6µs Latency in SW4: 4.0µs Send packet from SW4 to SW3: 52.8µs Transmit time SW4 to SW3: 2.5µs Latency in SW3: 4.0µs Send packet SW3 to SW2: 52.8µs Transmit time SW3 to SW2 2.5µs Latency in SW2: 4.0µs Send packet SW2 to SW1: 52.8µs Transmit time SW2 to SW1 2.5µs Latency in SW1: 4.0µs Send packet SW1 to Master: 528.0µs Total time: 767.5µs Cascading of 10/100 switches

Slide Mbit/s M M = Master; S = Slave; SW = Switch RS2 Application with one Master, 31 Slaves and 4 RS2-Switches SW1SW2SW3SW4 S1 S8S15S16S23S24S Mbit/s Upgrading all links to 100Mbps

Slide 14 Multicast from Master to all Slaves: Send packet from Master to SW1: 5.76µs Latency in SW1: 4.0µs Receive packet in Slave 1: 5.76µs Send packet S1 to SW2: 5.76µs Transmit time SW1 to SW2 : 2.5µs Latency in SW2: 4.0µs Send packet SW2 to SW3: 5.76µs Transmit time SW2 to SW3 2.5µs Latency in SW3: 4.0µs Send packet SW3 to SW4: 5.76µs Transmit time SW3 to SW4 2.5µs Latency in SW4: 4.0µs Receive packet in Slave 31: 5.76µs Total time taken: 52.3µs Receive packet at slave 1 Receive packet at slave 31 This time is called: Receive variance Upgrading all links to 100Mbps

Slide 15 All Slaves sending response to Master: Send packet Slaves to SW4: 5.76µs Latency in SW4: 4.0µs Send packet from SW4 to SW3: 52.8µs Transmit time SW4 to SW3: 2.5µs Latency in SW3: 4.0µs Send packet SW3 to SW2: 52.8µs Transmit time SW3 to SW2 2.5µs Latency in SW2: 4.0µs Send packet SW2 to SW1: 52.8µs Transmit time SW2 to SW1 2.5µs Latency in SW1: 4.0µs Send packet SW1 to Master: 52.8µs Total time: µs Upgrading all links to 100Mbps

Slide 16 Scan Times  Scan time of a 10Mbps network  312 µs µs = 2505 µs  Scan time of 10Mbps network with 100Mbps links between switches  156 µs µs = 924 µs  Scan time of 100Mbps network  52 µs + 240µs = 292 µs

Slide 17 Real-Time, Determinism and Ethernet  So can Ethernet cope with the demands of a real-time control network?  Scan times are as quick if not quicker than contemporary bus systems. Deterministic? Definitely in a controlled traffic network.  Worldwide, open standards means all vendors support Ethernet.  Flexibility means it already supports such things as remote video monitoring.  Evolutionary history means it can only get better!

Slide 18 The Future  How many disparate networks do you need between the information and device layers? Automation Control Interbus Loop ASI Interbus Seriplex Profibus DP Profibus FMS CAN CCLink ControlNet DeviceNet SDS WorldFIP / FIP LonWorks ETHERNET Profibus PA IEC/SP50 H1 IEC/SP50 H2 HART Device Information