2015_odva_conference_leurs-conversion-of-fieldbusses-final
TRANSCRIPT
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Conversion of Fieldbusses regarding Industrial Internet of Things
Ludwig Leurs
Bosch Rexroth AG
October 14, 2015
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Overview
• Development of fieldbusses in Factory Automation
• Requirements from Industrial Internet of Things / Industrie 4.0
• Future impact of Time Sensitive Networks on Industrial Ethernet
Technical Track 2015 Industry Conference & 17th Annual Meeting www.odva.org
© 2015 ODVA, Inc. All rights reserved. 2
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3
History of Fieldbusses
1980s
• Replacement of hardwired I/O connection to reduce wiring cost
• Data exchange between automation controllers
• Synchronized motion systems
Technical Track 2015 Industry Conference & 17th Annual Meeting www.odva.org
© 2015 ODVA, Inc. All rights reserved.
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Central I/O
Technical Track 2015 Industry Conference & 17th Annual Meeting www.odva.org
© 2015 ODVA, Inc. All rights reserved.
PL
CIO
Ra
ck 1
IO R
ack 2
Pa
ralle
l bus
Pa
ralle
l bus
Cab
ine
t1
IO R
ack 4
IO R
ack 5
Para
llel bus
Pa
ralle
l bus
Cab
ine
t2
IO R
ack 3
Serial connection
N -times
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I/O via Fieldbus
Technical Track 2015 Industry Conference & 17th Annual Meeting www.odva.org
© 2015 ODVA, Inc. All rights reserved.
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6
DeviceNet
• Introduced in 1995
• Based on CAN (ISO11898)
– widely used in vehicles
• Variety of application
– Master / Slave
– Client / Server
– Peer to Peer
– Cyclic, Change of State
– Unicast or Multicast
• Object oriented design
• Routing and bridging
Technical Track 2015 Industry Conference & 17th Annual Meeting www.odva.org
© 2015 ODVA, Inc. All rights reserved.
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Controller to Controller Communication
• Automation driven by automotive industries
• The 1980s: CIM, MAP/MMS driven by GM, initial point of Industrie 4.0
• Vertical integration
• Profibus/FMS was defined as a subset of MMS, main use C2C
• PC used for HMI and control Ethernet, TCP/IP
Technical Track 2015 Industry Conference & 17th Annual Meeting www.odva.org
© 2015 ODVA, Inc. All rights reserved.
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8
CNC, RC and Motion Control
• First applied in machine tools
• High precision and fast control loops needed
– Local control loops preferred
– Distribution of control loops depends on application
• Commissioning mostly online
Technical Track 2015 Industry Conference & 17th Annual Meeting www.odva.org
© 2015 ODVA, Inc. All rights reserved.
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9
Servo drive control loops
Technical Track 2015 Industry Conference & 17th Annual Meeting www.odva.org
© 2015 ODVA, Inc. All rights reserved.
Momentum / current control
loop
Speed control loop
Position control loop
U,IXcmd
Xcrnt
ncmd
ncrnt
d/dt
indirect direct feedback
Classical analog speed control interface ±10V
Position control interface(Standard interface forSERCOS)
Momentum/current control(used for non-cartesian systems, e.g. robotics)
+
-
+
-
+
-
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CNC, RC and Motion Control
• First applied in machine tools
• High precision and fast control loops needed
– local control loops preferred
– Distribution of control loops depends on application
• Commissioning mostly online
• First digital interface: Sercos
– Fiber optics for EMC
– TDMA for real time high precision timing
– Initially only drives
– Specialized for synchronized motion
Technical Track 2015 Industry Conference & 17th Annual Meeting www.odva.org
© 2015 ODVA, Inc. All rights reserved.
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Differences in Application Properties
• Different usage different properties
• Offline configuration EDS
• Machine only working with all drives error if one is missing
Technical Track 2015 Industry Conference & 17th Annual Meeting www.odva.org
© 2015 ODVA, Inc. All rights reserved.
I/O C2C Motion
Offline configuration X
Online configuration X
Config at connection X X
Cycle time 5-10ms 5-100ms 0.5-4ms
Synchronization < ±5% - <1µs
Browse X
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Migration to Ethernet
• Reasons and requirements
– Data rate insufficient in fieldbusses
– Eliminate separate interface for commissioning
– Enable IT integration into devices
• Web server
– Diagnostics
– Change settings
• Firmware download
• SNMP
• How to become Ethernet deterministic
Technical Track 2015 Industry Conference & 17th Annual Meeting www.odva.org
© 2015 ODVA, Inc. All rights reserved.
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Real Time Behavior (1)
• Traditional Ethernet using CSMA/CD is not deterministic
– Collision is detected and packets are repeated after random time
– But can be made deterministic by a Master/Slave MAC layer (PowerLink)
• Switched Ethernet and packet prioritization achieves soft real time behavior
– Packet delay up to 122 µs per hop
– Still danger of overload and switches not supporting enough priorities
– Not suitable for synchronized motion
– Synchronized motion can be achieved using synchronization with IEEE1588
• Ultra low latency and Ethernet
– Scheduled transfer (TDMA) and multi-device packets (Sercos, Profinet IRT)
– Future: Time Sensitive Networks (TSN)
13Electric Drives and Controls | 20.06.2012 | DC-IA/PJ-ETH | © Bosch Rexroth AG 2012. Alle Rechte vorbehalten, auch bzgl. jeder Verfügung, Verwertung, Reproduktion, Bearbeitung, Weitergabe sowie für den Fall von Schutzrechtsanmeldungen.
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Electric Drives and Controls | 20.06.2012 | DC-IA/PJ-ETH | © Bosch Rexroth AG 2012. Alle Rechte vorbehalten, auch bzgl. jeder Verfügung, Verwertung, Reproduktion, Bearbeitung, Weitergabe sowie für den Fall von Schutzrechtsanmeldungen.
Adapted from: J. Jasperneite, FH Lemgo
Real Time Behavior (2)
Software Architecture
Real Time Class
Best-effort
Real Time
TCP/UDP
IP
Ethernet MAC
1
e.g. Modbus, FF HSE
Best-effort
Real Time
TCP/UDP
IP
Ethernet MAC
2
Profinet RT, EtherNet/IP
Prioritizing
Best-effort
Real Time
TCP/UDP
IP
Ethernet MAC
3
Profinet IRT, Sercos,
PowerLink, EtherCAT
Scheduling
Performance
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Market Requirements
15Technical Track 2015 Industry Conference & 17th Annual Meeting www.odva.org
© 2015 ODVA, Inc. All rights reserved.
Ford Motor Company
Minimum product variation
High variation of products, minimum buffers
Toyota
Future: Individual products in mass production
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16
SmartFactory Demo Line• Product: card holder
• Product contains
individual
manufacturing steps
and quality data
• Plan to use Machine
Data Model of ODVA
Machinery SIG
166/23/2015 | Ludwig Leurs | © Bosch Rexroth AG 2015. All rights reserved, also regarding any disposal, exploitation, reproduction, editing, distribution, as well as in the event
of applications for industrial property rights.
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Ubiquitous availability of information
• Every information at any place at any time
• Wireless is the key
– Already available via mobile devices
– In some applications also at device level
• CIP is ready
– Objects and services
– Bridging and routing
– Future extension
• DeviceNet of Things
• EtherNet/IP in resource constrained devices
• I/O-Link integration
Technical Track 2015 Industry Conference & 17th Annual Meeting www.odva.org
© 2015 ODVA, Inc. All rights reserved.
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Discovery Service
• IIoT needs information to be found online
• OPC (and OPC UA) offers a browse service
• Industrial systems based on offline configuration
EDS files
• Systems originating from online configuration
built in object directory, e.g. Sercos: S-0-0017,
Parameter structure contains units, names, data
type, …
• Solution: link to EDS from device
Technical Track 2015 Industry Conference & 17th Annual Meeting www.odva.org
© 2015 ODVA, Inc. All rights reserved.
Cloud
file://host/dev.eds
S-0-0017
browse
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TSN Standards Overview
• Set of Standards
• Time Synchronization
– 1588, 802.1AS, 801.2ASrev
• Latency reduction
– 802.1Qbu, 802.3br
– 802.1AB (LLDP)
• Scheduling traffic
– 802.1Qbv
• Redundancy
– 802.1CB
Technical Track 2015 Industry Conference & 17th Annual Meeting www.odva.org
© 2015 ODVA, Inc. All rights reserved. 19
CB
QbvQ
3brTSN
Qbu
Qci
Qca
Qcc
ASRev1722
Qav
Qch
AS1733
Qat
1588
Legend:TSNAVBEthernetTransport
AB
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Time Synchronization
• Nearly all systems use some
variant of IEEE1588
• Transparent clocks have been
introduced to minimize degrading
of accuracy over hop count
• Redundancy issues have been
solved by sophisticated methods
• Only Sercos uses
synchronization by telegram
Technical Track 2015 Industry Conference & 17th Annual Meeting www.odva.org
© 2015 ODVA, Inc. All rights reserved.
MasterNode
2 PortNode
2 PortNode
2 PortNode
t
Grand-Master
Transp. Clock
Transp. Clock
Ord. Clock
Daisy chain degrades accuracy
Optimum is star topology
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21
Latency Reduction – Frame Preemption
• Long frames can‘t be interrupted in
traditional Ethernet
• Qbu (Frame Preemption) and 3br
(Interspersing Express Traffic)
solve this
• Maximum delay by low priority
traffic can be reduced from 123µs
to 12µs @100Mbit/s
• But this still allows this delay to be
introduced at each hop
Technical Track 2015 Industry Conference & 17th Annual Meeting www.odva.org
© 2015 ODVA, Inc. All rights reserved.
1 2 … 3 3…
…1 2 2 2…
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22
Latency Reduction – Scheduled Traffic
• Problem: large number of hops
– Scheduling can reduce latency
significantly
• IEEE802.1Qbv Time aware
shaper
– Block non-express traffic in the
guard window immediately
before cycle start
• Only in large networks
– Probably not in EtherNet/IP
– Needed in Sercos
Technical Track 2015 Industry Conference & 17th Annual Meeting www.odva.org
© 2015 ODVA, Inc. All rights reserved.
Queue: time critical
traffic
Queue: rate constrained
traffic
Queue:best effort traffic
Queue:……
Transmission Gate
Transmission Gate
Transmission Gate
Transmission Gate
Gate control list
T01: OCCCT02: COCCT03:.COOO….T79: RepeatTAS CBS CBS CBS
Transmission selection
Open Close Close Close
Cycle start
Non express traffic blocked
1 1 2
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Redundancy
• Industrial networks support
redundancy already
• Change to 802.1CB would
introduce different procedures
– Incompatibilities
• No need, if no requirement from
application
Technical Track 2015 Industry Conference & 17th Annual Meeting www.odva.org
© 2015 ODVA, Inc. All rights reserved.
slave 1
primary channel
Master
secondary channel
slave 2 slave 3
P1 P2 P1 P2 P2 P1
P1 P2 P1 = Port1
P2 = Port2
Beacon
protocol
EtherNet/IP
Sercos
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24
100Mbit/s versus 1Gbit/s
• What happens going from 100 Mbit/s to 1Gbit/s?
– Transmission speed increases by factor 10
– Propagation delay stays constant (no increase in speed of light)
– Signal conversion delay decreases insignificantly
Technical Track 2015 Industry Conference & 17th Annual Meeting www.odva.org
© 2015 ODVA, Inc. All rights reserved.
Packet size 100 Mbit/s
1 Gbit/s
Transmission time1) 64 6.7µs 0.67µs
1518 123µs 12.3µs
Delay per hop2) 1.5µs 1.5µs
1) Including Start of Frame and Inter Packet Gap
2) 1 µs node delay and 0.5µs accounting for 100 m cable length
Topology matters!
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25
100Mbit/s versus 1Gbit/s – cut through
• Total delay with Cut through
– Transmission time important at
100Mbit/s
– Node delay dominant at 1Gbit/s
Technical Track 2015 Industry Conference & 17th Annual Meeting www.odva.org
© 2015 ODVA, Inc. All rights reserved.
0
50
100
150
200
250
300
1 10 20 30 40 50 60 70 80 90 100
µs
Number of Hops
100M-64B
1000M-64B
100M-1518B
1000M-1518B
trDND tntt
on timetransmissi:trt
Delay Node:DNt
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100Mbit/s versus 1Gbit/s – store & forward
• Total delay with store & forward
– 100Mbit/s:
• Transmission time dominant for
large packets
• Large number of hops lead to
large delay
• Not useful for closed loop control
• But for small packets only systems
may be acceptable
• TSN Frame preemption would be
helpful
– 1Gbit/s
• Small packets: node delay and
transmission time in same range
Technical Track 2015 Industry Conference & 17th Annual Meeting www.odva.org
© 2015 ODVA, Inc. All rights reserved.
trDND tntt
on timetransmissi:trt
Delay Node:DNt
0.0
2,000.0
4,000.0
6,000.0
8,000.0
10,000.0
12,000.0
14,000.0
1 10 20 30 40 50 60 70 80 90 100
µs
Number of Hops
100M64B
1000M64B
100M1518B
1000M1518B
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27
100Mbit/s versus 1Gbit/s – store & forward
• Total delay with store & forward
– Low number of hops
– 100Mbit/s:
• Transmission time still important
• closed loop control
• But for small packets only systems
may be acceptable
• TSN Frame preemption would be
helpful
– 1Gbit/s
• Small packets: node delay and
transmission time in same range
Technical Track 2015 Industry Conference & 17th Annual Meeting www.odva.org
© 2015 ODVA, Inc. All rights reserved.
trDND tntt
on timetransmissi:trt
Delay Node:DNt
0
50
100
150
200
250
300
1 10
µs
Number of Hops
100M64B
1000M64B
100M1518B
1000M1518B
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Summary
• Automation technology developed in several application fields
• Ethernet was introduced for transmission rate and IT connectivity
• ODVA uses COTS technology and supports internetworking in its
specification
• CIP is ready for the Industrial Internet of Things
• Discovery service could be added
• When TSN becomes available EtherNet/IP could be easier to apply in time
critical applications in the presence of IT traffic
• The formerly separated application fields can be merged into one network
(this is already true for EtherNet/IP)
Technical Track 2015 Industry Conference & 17th Annual Meeting www.odva.org
© 2015 ODVA, Inc. All rights reserved.
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