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Industrial Profile for IEEE 802.1BA
Status Medienredundanz
Franz-Josef Goetz
Mai 2009
Siemens
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Industry
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Communication Services in Industry
Best Effort Traffic
- Configuration
- Diagnostic
- Web Services
- Events
-
RT-Low Streams
- General Automation to exchange typical anlog an digital values(manufactoring and process industry)
RT-High Streams- Motion Control to exchange typical anlog and digital values
(synchronized processes)
AV Streams
- Vision Systems(inspection, identification, tracking, counting and measurement)
Configuration
DiagnosticWEB Services
EventsGeneral
Automation
Synchr.
Process
Industrial Node
Best Effort TrafficRT-Low
Stream
RT-High
Stream
Ethernet
AV
Stream
Vision
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Streams for Time Sensitive Data in Industry
RT-Streams:
- time sensitive Data
- periodic transmission
Guaranteed QoS for RT-Streams along the end-to-end path:
- guaranteed low latency (low delay variation / jitter)
- guaranteed ressources (no packet loss)
- guaranteed bandwidth (throughput)
- deterministic behaviour in case of high network load
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Industrial Communication
IT-Services
IternetIternet
Factory AutomationEnergy Automation
Power Distribution
Motion Control
Best Effort Traffic
RT-High
Streams
RT-Low
Streams
125s100ms
Process Industry
Typical Application Cycle
or Reaction Time
Communication Services
AV- Streams
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Application Model in Industy (1)
The application model for RT-Streams in industry is differentfrom the application model used for AV-Streams.
Closed Loop application (real procecss, control application and communication)
Dead time shall be kept small to get short reaction time
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Application Model in Industy (2)
Node 1
Node 2
RT-Streams
Data Cycle
Node 3
Application
Data CycleData Cycle
Application
Application
Data Cycle
Application
Application
Application
Application
Application
Application
Application
Application Application
Control applications are synchroniced
Minimized jitter for communication and application
No buffering for RT-Data (just in time)
Consistent process image is required
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Use Cases
RT-Low Streams
Data Length < 300 bytes
Data Cycle < 1ms
32 devices per line
Latency < 1ms
Bay
Controller
Merging
Unit
MergingUnit
PLC
Actor-Sensor
Input /Output
Actor-
SensorActor-Sensor
RT-High-Streams
Data Length < 100 bytes
Data Cycle ~ 125s (typical)
Up to 16 devices in line
Latency < 125s
PLC
Input/Output
Drive
Drive
Drive
Power Distribution(IEC 61850)
Factory AutomationPower Industry
Motion Control
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Typical Topology for Bridged LANs in Industry
LinearTopology (Line, Ring)
Applications mostly feature distributed linear dimension, i.e. production lines
The network is tailored to the application, i.e. line topologies
To reduce total cost, 2-port-bridges are integrated into the end stations
For enhanced availability, lines are closed to rings
Homogeneous segments (100MBit or GBit)
Core
Distribution
+ Access
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Requirements for RT Streams
Low Latency for RT Streams
- RT-Low Streams: Latency < 1ms over 32 hops, data < 300 Bytes- RT-High Streams: Latency < 125s over 16 hops, data < 100 Bytes
(-> avoid interference Best Effort Traffic with RT Traffic)
Transmission Period for RT Streams
- RT-Low Streams: 500s .. 4ms- RT-High Streams: 125s .. 1ms
Synchronization
- End point time synchronization accuracy over 64 hops < 1s
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Requirements for RT Streams
Routing for AV and RT Steams
- No loss of AV and RT Streams caused by RSTP during network reconfiguration
- Shortest Path for RT Streams (low latency)-> do not use learning mechansim for RT Streams
Redundancy
- Alternate path for RT Streams (i.e. in ring topology)
Communication Relation for RT Streams
- Unidirectional RT Streams (Publisher -> Subscriber)
- Bidirectional RT Streams (Client Server ) PLC
Input-
OutputDevice
Input-
OutputDevice
PLC
Output
Device
Input
Device
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Integration of Industrial Communication in network
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Open Issues
AVB and 802.1 includes mechanism to control AV Streams.Simular mechansim may be used for RT-Streams.
Include extensions for stream handling to reduce latency?
Can we describe the extensions in an industrial profile?
How to proceed for industrial profile?
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Thank you !