1 Ludwig Winkel, Karl Weber IEEE 802.1 RTE 2004-01-14.ppt P:# Realtime Ethernet concept Realtime...

Ludwig Winkel, Karl Weber IEEE 802.1 RTE 2004-01-14.ppt P:#1

Realtime Ethernetconcept

Realtime Ethernetconcept


Ethernet communication in automation

Coexistent use of realtime and IT communicationon one line

Uniform realtime protocol for all requirements

Scalable realtime communication from high-performance to isochronous

TCP/IP

Real-time

<1ms10ms100ms

Motion controlField devicesController and HMI

Ethernet as multi-purpose bus


PhLayer (1)

ISO/OSI Referenz Model

Data Link Layer (2)

Network (3)

Transport (4)

Application (7)

User

IEEE 802.1, IEEE 802.3, IEEE 1588, IEEE 802.x....

Modem, ISDN, wireless. ...

ControlNet/IP

Encapsulation

CIP

TCP UDP

IP

PROFInet

DCOM

IP

TCP UDP

Run time; RT-Auto; ACCO

RealTime Class 1

?????

FF-HSE

FMS| SMKP| MIB

FDA| SNTP|SNMP

IP

TCP UDP

FB AP| NMA| MIB

SMK

Technology specific

RealTime Ethernet Class 2

OPC-DX

Identical for all CPF

IEC 61158 & IEC 61784 Ethernet based C.(IEC SC65C Digital Communication)

1784-1 based


Realtime = deterministic data transmission

Ethernet = industrial communication based on IEEE 802 and switching technology

Realtime Ethernet (RTE) classes

No RTE: no provisions for deterministic communication

Low end = Class 1: Cycle times in the range from 5 to 10 msec. Fully compatible with the IP standard and no restrictions on networking components.

High end = Class 2: Cycle times in the range from 0,25 to 5 msec. Fully compatible with the IP standard with networking components supporting RTE Option.

Realtime Ethernet


RTE Class 2 covers the requirements for the motion control applications market segment.

RTE Class 2 shall be also fully compatible with the IP standard - with no restrictions.

RTE Class 2 for motion control


Wood-, glass-and ceramic-processing machines

Plastics injection molding

machines

Packaging machines

Printing presses

Requirements for motion control applications

Real-time capability


RTE utilizes switching technology: Standard in the office world

Prospects for higher data rates

A large number of stations

Wide network expansion (cascades of 20 or more)

Electrical: 100 m per segment FO: 3 km per segment

Full-duplex capability

Data streams remain local and do not place load on the entire network

Simple configuring rules

Switching technology - the basis for RTE


2 SRT

Offener TCP/IP Kanal Geräteparametrierung Lesen von Diagnosedaten Laden von Verschaltungen Aushandeln des

Kommunikations-kanals für Nutzdaten

Echtzeit Kanal SRT Performante Übertragung Zyklische Daten Ereignisgesteuerte Meldungen

1

2

1

1

2

Open IP channel Device parameterization Reading of diagnostics data Loading of interconnections Negotiation of the

communication channel for user data

RTE Class 1 channel High-performance transfer Priority Tagging Cyclic data Event-controlled signals

RTE Class 2 channel High-performance transfer Data in isochronous mode Jitter <1μsec

Real-

tim

e3

RTE Cl.1

RTE Cl.2Real-time

switch

3

2

1

Ethernet

TCP / UDP

Industrial automation applications

IT appli-cationse.g. HTTP SNMP DHCP...

Standard data

Real-time data

IP

The RTE class 1 and 2 communication- an integrated and scalable solution -

Communication architecture with Switch


reservierte Spur für IRT

SRT - Spu

rTCP/IP

TCP/IP TCP/IP

TCP/IPTCP/IP

TCP/IPRT

TCP

/IP

RT

RT

TCP/IP

TCP/IP

TCP/IP

TCP/IP

TCP/IP

TCP/IPRT

TCP

/IP

RT

TCP

/IP

RT

TCP/IPTCP/IP TCP/IPRT

RTE-Protocol get priority compared to TCP/IP-protocol.

In case of a traffic jam, even the class 1 traffic stuck

Separate track to guarantee realtime

RTE Cl.1RTE Cl.1

RTE Cl.2RTE Cl.2

Non RTENon RTETCP/IP

RT TCP/IP

TCP/IP

RT

RT

RTRT

Traf

fic

jam

jam

jam


Cycle 1 Cycle 2 Cycle n

RTE channel

Openchannel

(IP)RTE

channel

Openchannel

(IP)

E.g. 1 ms position control cycle

IP dataRTE data

Deterministic communication Open communicationSynchro-nization

Communication system scheduling

- separate time domains for real-time and non-real-time -

Concept for RTE Class 2


*) Standard length of the IP data packets from 64 to 1536 bytes Max. data transmission rate on Fast Ethernet: 12 MB/sec

Cycle time

Jitter

Number of nodes

Simultaneously transferable TCP/IP data *)

1 msec

<1µsec

35

9MB/sec

75

6MB/sec

250 µsec

<1µsec

18

6MB/sec

Performance parameters for RTE Class 2


Occurence n

t

Non RTERTE Cl.1

100 msec

10 msec

Distribution of updating times

0.25...1.0 msec

15% 100%

RTE Cl.2


Consequences to IEEE 802

Enhancements to the IEEE 802.1D:2003 standard for RTE switched networks :

Amend RTE Option

In IEEE 802.1D or

Specify it separately in IEEE P802.1 or

Specify it separately in IEC SC65C.

Detailed Concepts will be described in IEC SC65C (IEC 61784-2)

Technical topics of the RTE option see next pages


Technical issues on real time switching

Synchronized behaviour based on IEEE 1588-Sync●Common cycle time●Coordinated start of real time schedule

Scheduled forwarding ●Shut down of non real time(RT) processing prior to RT phase●Disable non RT forwarding while a port is in RT phase●Scheduling list may be used to guarantee precise delivery

Coordination of application and communication●Ability to run control loops ●Eliminate jitter of communication cycle by timestamping

Fast recovery from communication problems●Use redundant paths●Include a means for duplication detection

1 Ludwig Winkel, Karl Weber IEEE 802.1 RTE 2004-01-14.ppt P:# Realtime Ethernet concept Realtime...

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