Realtime Ethernet
concept
1
Ludwig Winkel, Karl Weber IEEE 802.1 RTE 2004-01-14.ppt P:#
Ethernet as multi-purpose bus
Controller
and HMI
100ms
Field devices
Motion control
10ms
<1ms
TCP/IP
Real-time
Ethernet communication in automation

Coexistent use of realtime and IT communication
on one line

Uniform realtime protocol for all requirements

Scalable realtime communication from high-performance
to isochronous
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Ludwig Winkel, Karl Weber IEEE 802.1 RTE 2004-01-14.ppt P:#
IEC 61158 & IEC 61784 Ethernet based C.
(IEC SC65C Digital Communication)
OPC-DX
User
Application (7)
Transport (4)
Real
Time
Class
1
ControlNet/
IP
CIP
PROFInet
Run time;
RT-Auto;
ACCO
?????
FF-HSE
1784-1 based
FB AP| NMA| MIB
SMK
FMS| SMKP| MIB
DCOM
FDA| SNTP|SNMP
Encapsulation
TCP
UDP
TCP
UDP
TCP
UDP
Network (3)
IP
Data Link
Layer (2)
PhLayer (1)
ISO/OSI
Referenz
Model
IP
IP
RealTime Ethernet Class 2
Modem, ISDN, wireless. ...
IEEE 802.1, IEEE 802.3, IEEE 1588, IEEE 802.x....
Technology specific
Identical for all
CPF
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Ludwig Winkel, Karl Weber IEEE 802.1 RTE 2004-01-14.ppt P:#
Realtime Ethernet
Realtime
= deterministic data transmission
Ethernet
= industrial communication based on IEEE 802
and switching technology
Realtime
No
Ethernet (RTE) classes
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.
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Ludwig Winkel, Karl Weber IEEE 802.1 RTE 2004-01-14.ppt P:#
RTE Class 2 for motion control

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.
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Ludwig Winkel, Karl Weber IEEE 802.1 RTE 2004-01-14.ppt P:#
Requirements for motion control applications
Real-time
capability
Wood-, glassand ceramicprocessing
machines
Plastics
injection
molding
machines
Packaging
machines
Printing
presses
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Ludwig Winkel, Karl Weber IEEE 802.1 RTE 2004-01-14.ppt P:#
Switching technology - the basis for RTE
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
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Ludwig Winkel, Karl Weber IEEE 802.1 RTE 2004-01-14.ppt P:#
Communication architecture with Switch
 The RTE class 1 and 2 communication
- an integrated and scalable solution 1 Open
Offener
IP TCP/IP
channelKanal

IT applications



1
Standard data
Real-time data
TCP / UDP
2 RTE
Echtzeit
Class
Kanal
1 channel
SRT
IP
2
Ethernet
switch
Real-time
e.g.
 HTTP
 SNMP
 DHCP...
Industrial automation applications
Device parameterization
Geräteparametrierung
Lesen von
Reading
of Diagnosedaten
diagnostics data
Laden von
Loading
of Verschaltungen
interconnections
Aushandeln of
Negotiation
des
the
Kommunikationscommunication
channel for
kanals
user
data
für Nutzdaten


SRT
2 RTE 3 RTE
Cl.1
Cl.2
Real-time


High-performance
Performante
Übertragung
transfer
Zyklische
Priority
Tagging
Daten
Ereignisgesteuerte
Cyclic
data
Meldungen
Event-controlled
signals
3
RTE Class 2 channel



High-performance transfer
Data in isochronous mode
Jitter <1μsec
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Ludwig Winkel, Karl Weber IEEE 802.1 RTE 2004-01-14.ppt P:#
RT
Separate track to
guarantee realtime
RTE Cl.2
RT
T
p
-S
RT
TCP/IP
TCP/IP
RT
TCP/IP
TCP/IP
TCP/IP
TCP/IP
TCP/IP
In case of a
traffic jam,
even the class
1 traffic stuck
RT
TC
P
/IP
RTE-Protocol get
priority compared to
TCP/IP-protocol.
TC
P
RT
/IP
SR
RT
reservierte Spur für IRT
ur
RTE Cl.1
TCP/IP
TCP/IP
RT
TCP/IP
TCP/IP
RT
RT
TCP/IP
TCP/IP
TCP/IP
TCP/IP
RT
TC
P
/IP
TCP/IP
TCP/IP
RT
Non RTE
TCP/IP
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Ludwig Winkel, Karl Weber IEEE 802.1 RTE 2004-01-14.ppt P:#
Concept for RTE Class 2
 Communication system scheduling
- separate time domains for real-time and non-real-time -
Open
channel
(IP)
RTE
channel
Cycle 1
Open
channel
(IP)
RTE
channel
Cycle 2
Cycle n
E.g. 1 ms position control cycle
Synchronization
Deterministic communication
Open communication
RTE data
IP data
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Ludwig Winkel, Karl Weber IEEE 802.1 RTE 2004-01-14.ppt P:#
Performance parameters for RTE Class 2
Cycle time
1 msec
250 µsec
Jitter
<1µsec
<1µsec
Number of
nodes
Simultaneously
transferable
TCP/IP data *)
*)
35
75
18
9
6
6
MB/
sec
MB/
sec
MB/
sec
Standard length of the IP data packets from 64 to 1536 bytes
Max. data transmission rate on Fast Ethernet: 12 MB/sec
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Ludwig Winkel, Karl Weber IEEE 802.1 RTE 2004-01-14.ppt P:#
Distribution of updating times
Occurence n
RTE Cl.2
RTE Cl.1
15%
0.25...1.0
msec
10
msec
Non RTE
100%
100
msec
t
12
Ludwig Winkel, Karl Weber IEEE 802.1 RTE 2004-01-14.ppt P:#
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
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Ludwig Winkel, Karl Weber IEEE 802.1 RTE 2004-01-14.ppt P:#
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
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Ludwig Winkel, Karl Weber IEEE 802.1 RTE 2004-01-14.ppt P:#