Integrated Motion On EtherNet/IP: Maximizing Network Performance
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Transcript of Integrated Motion On EtherNet/IP: Maximizing Network Performance
Copyright © 2014 Rockwell Automation, Inc. All Rights Reserved.
PUBLIC INFORMATION
AD19 - Integrated Motion On EtherNet/IP: Maximizing Machine Performance
Copyright © 2014 Rockwell Automation, Inc. All Rights Reserved.
This session is focused at helping designers of EtherNet/IP based motion systems to: Understand the fundamental principles behind the core
technology (CIP Motion) and its relationship to time Discover how the use of time in the architecture allows for
determinism and provides a platform for high performance control Gain insight into infrastructure selection, network arrangement
and how devices with ‘CIP Sync’ technology can also be applied to a high performance, deterministic control solution
Session Description
Copyright © 2014 Rockwell Automation, Inc. All Rights Reserved.
Keeping it all in perspective
3
This presentation focuses on the fundamentals of CIP Motion and CIP Sync technologies and the relationship of time and position in the system. It correlates these basic parameters of a CIP Motion architecture against the network infrastructure and helps the designer to understand how to apply best practices for an infrastructure which communicates the proper timing and positioning information in these systems.
However given this, the variations introduced by networking infrastructure are measured in nanoseconds and microseconds. Fluctuations introduced by the network are usually negligible compared to other boundaries in the system:
Compliance and backlashMechanical system time constantsSystem Tuning
Copyright © 2014 Rockwell Automation, Inc. All Rights Reserved.
EtherNet/IP - Enabling/DrivingConvergence of Control and Information
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Industrial Network Convergence
Converged Plantwide EtherNet/IPIndustrial Network Model
Corporate Network
Sensors and otherInput/Output Devices
Motors, DrivesActuators
SupervisoryControl
Robotics
Back-Office Mainframes andServers (ERP, MES, etc.)
OfficeApplications,Internetworking,Data Servers,Storage
Human MachineInterface (HMI)
SafetyController
Traditional – 3 TierIndustrial Network Model
Corporate Network
Sensors and otherInput/Output Devices
Controller
Motors, DrivesActuatorsRobotics
Back-Office Mainframes andServers (ERP, MES, etc.)
OfficeApplications,Internetworking,Data Servers,Storage
Control NetworkGateway
Human MachineInterface (HMI)
SupervisoryControl
Camera
Phone
Industrial NetworkIndustrial Networks
SafetyI/OI/O
Controller
Copyright © 2014 Rockwell Automation, Inc. All Rights Reserved.
CIP Motion coordinates devices in a manner that’s similar to our own methods for coordinating meetings and events All members (devices) have clocks
to compare time to an absolute base and scale
A destination (position) is targeted for the event
A time (timestamp) is set for when the event shall occur
A message is sent to each member (device) to meet at the given place at the pre-determined time Not all messages might arrive at
precisely the same time!
Birthday Party!Cafeteria12:00 pm
Fundamental Principal of CIP Motion Control
Copyright © 2014 Rockwell Automation, Inc. All Rights Reserved.
Cafeteria
CIP Motion coordinates devices in a manner that’s similar to our own methods for coordinating meetings and events All members (devices) have clocks to
compare time to an absolute base and scale
A destination (position) is targeted for the event
A time (timestamp) is set for when the event shall occur
A message is sent to each member (device) to meet at the given place at the pre-determined time Not all messages might arrive at
precisely the same time! But all members arrive in the proper
position at the proper time for the event to take place!
Fundamental Principal of CIP Motion Control
Copyright © 2014 Rockwell Automation, Inc. All Rights Reserved.
Motion Task
Target Time =Tctr0 + 2*CUP
Tctr0
Servo Update Period
Course Update Period (CUP)
Delivering Command Position with Time Stamp allows Drive to Compute a Trajectory to hit the Command Position at the Target Time.
Tctr1 Tctr2
Drive Task
Fine Interpolation Polynomial Target Time
Target CommandPosition
Last Target Time
Last CommandPosition
Motion Task
Drive Task
Controller
Drive
AxisRotation
Command Position Targeting Using Time Stamp
KPI-1 = Tracking Error = Command Position (N-2) – Actual Position (N)
Copyright © 2014 Rockwell Automation, Inc. All Rights Reserved.
How is time synchronized in the system?Precision Time Protocol (PTP) Overview
Creates a master/slave hierarchy of clocks in the network
Best Master selection Grandmaster transmits accuracy
properties with Announce msg Slaves pick best master
Synchronization timing messages Between master and slave Frequency Synchronization
Sync, Followup Msgs Phase / Delay Measurements
Slave to Master Delay_Req, Delay_Resp Msgs
Master Clock Slave ClockTS
TS
Delay = (D1 + D2) / 2 time
TS
TS
TS
TS
TS Time Stamp
D1
D2
Copyright © 2014 Rockwell Automation, Inc. All Rights Reserved.
If clocks are off, members don’t know that their clocks are different from others against which they are coordinating All members (devices) continue
to compare time to an absolute base and time scale
A destination (position) is targeted for the event
A time (timestamp) is set for when the event shall occur
A message is sent to each member (device) to meet at the given place at the pre-determined time
Birthday Party!Cafeteria12:00 pm
What happens if the clocks are off?
Copyright © 2014 Rockwell Automation, Inc. All Rights Reserved.
Cafeteria
If clocks are off, members don’t know that their clocks are different from others against which they are coordinating All members (devices) continue to
compare time to an absolute base and time scale.
A destination (position) is targeted for the event
A time (timestamp) is set for when the event shall occur
A message is sent to each member (device) to meet at the given place at the pre-determined time Members will arrive at the right
place…. But at the wrong time…. ….this results in positioning error…
PositioningError
12:00 12:00
11:50 11:50
What happens if the clocks are off?
Copyright © 2014 Rockwell Automation, Inc. All Rights Reserved. 11
ReferenceAxis Clock
= 3:00
FollowerAxis Clock
thinks it’s 3:00
Time
Posit
ion
PositionError
What happens if the clocks are off?
KPI-2 = Registration Position Skew
Copyright © 2014 Rockwell Automation, Inc. All Rights Reserved.
How would clocks become offset?
Network infrastructure is a potential filter to the distribution of time in a system.
Although time is metered precisely from the master clock……it may not be precisely delivered through the infrastructure distribution depending on traffic loading and infrastructure configuration…
3:01 3:02 3:03 3:04 3:05 3:06 3:07 3:08
3:01 3:02 3:03 3:04 3:05 3:06 3:07 3:08
KPI-3 = Registration Time Skew
Copyright © 2014 Rockwell Automation, Inc. All Rights Reserved.
How would clocks become offset?
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M
S
Introduction of random, large volumes of data in a non-prioritized manner
Introduction of large packet sizes1500 bytes @ 100MBits/sec = 120 usecs
Non-PTP Enabled Switch
Copyright © 2014 Rockwell Automation, Inc. All Rights Reserved.
Device Clock Filtering Not user configurable
Topological Arrangement
Time Re-phasing Mechanisms Boundary Clock Transparent Clock
Traffic Prioritization QoS – Quality of Service DSCP - Differentiated Services
Code Point CIP Prioritization (ODVA
Specification) IGMP Snooping
Management of Multi-Cast Traffic
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Typically Managed Switch Other Mechanisms
How do I protect time in the system?
Copyright © 2014 Rockwell Automation, Inc. All Rights Reserved.
Advantages: Ability to segment network (minimize network latency and jitter) Network diagnostics and security features Some provide security protocols Some run loop prevention protocols Some deliver Quality of Service (QoS) Some multicast management (IGMP) Some support precision time protocol (PTP)
Disadvantages: Higher initial cost than an unmanaged switch Some technical knowledge needed for setup
Managed Switches
15
Copyright © 2014 Rockwell Automation, Inc. All Rights Reserved.
Does this mean I can’t use an unmanaged switch?
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No! You can use an unmanaged switch as long as you understand some key principles….
Copyright © 2014 Rockwell Automation, Inc. All Rights Reserved.
Advantages: Simplified design and deployment Ideal for small, isolated networks Lower initial investment than a managed switch
Disadvantages: No diagnostics No security No loop prevention No QoS or prioritization of some traffic at the expense of other traffic No PTP or adjustment to time stamp after passing packet No IGMP Snooping capability for multicast traffic management
Unmanaged Switches
17
Copyright © 2014 Rockwell Automation, Inc. All Rights Reserved.
Using Multiple Unmanaged Switches in a Large System…
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Copyright © 2014 Rockwell Automation, Inc. All Rights Reserved.
Multiple Unmanaged Switches in a Large SystemJitter at 0% Network Loading…
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With no network load, there was little difference between test cases
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500
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2500
0 2000 4000 6000 8000 10000 12000 14000
Clock Jitter (Nanoseconds)"Golden" Axis (Connected directly w/o switch
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1200
0 2000 4000 6000 8000 10000 12000 14000
Clock Jitter (Nanoseconds)Axis Switch 1
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0 2000 4000 6000 8000 10000 12000 14000
Clock Jitter (Nanoseconds)Axis Switch 2
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0 2000 4000 6000 8000 10000 12000 14000
Clock Jitter (Nanoseconds)Axis Switch 3
Copyright © 2014 Rockwell Automation, Inc. All Rights Reserved.
Multiple Unmanaged Switches in a Large SystemJitter at 40% Network Loading…
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0200400600800
1000120014001600
0 2000 4000 6000 8000 10000 12000 14000
Clock Jitter (Nanoseconds)"Golden" Axis (Connected directly w/o switch
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0 2000 4000 6000 8000 10000 12000 14000
Clock Jitter (Nanoseconds)Axis Switch 1
020406080
100120140
0 2000 4000 6000 8000 10000 12000 14000
Clock Jitter (Nanoseconds)Axis Switch 2
010203040506070
0 2000 4000 6000 8000 10000 12000 14000
Clock Jitter (Nanoseconds)Axis Switch 3
Copyright © 2014 Rockwell Automation, Inc. All Rights Reserved.
Multiple Unmanaged Switches in a Large System Jitter at 80% Network Loading…
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0
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1000
1500
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0 2000 4000 6000 8000 10000 12000 14000
Clock Jitter (Nanoseconds)"Golden" Axis (Connected directly w/o switch
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0 2000 4000 6000 8000 10000 12000 14000
Clock Jitter (Nanoseconds)Axis Switch 1
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0 2000 4000 6000 8000 10000 12000 14000
Clock Jitter (Nanoseconds)Axis Switch 2
01020304050607080
0 2000 4000 6000 8000 10000 12000 14000
Clock Jitter (Nanoseconds)Axis Switch 3
Copyright © 2014 Rockwell Automation, Inc. All Rights Reserved.
Same Test Using PTP Managed SwitchJitter at 80% Network Loading…
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0
5000
10000
15000
20000
25000
0 2000 4000 6000 8000 10000 12000 14000
Clock Jitter (Nanoseconds)"Golden" Axis (Connected directly w/o switch
0
5000
10000
15000
20000
25000
30000
35000
0 2000 4000 6000 8000 10000 12000 14000
Clock Jitter (Nanoseconds)Axis Switch 1
05000
100001500020000250003000035000
0 2000 4000 6000 8000 10000 12000 14000
Clock Jitter (Nanoseconds)Axis Switch 2
05000
100001500020000250003000035000
0 2000 4000 6000 8000 10000 12000 14000
Clock Jitter (Nanoseconds)Axis Switch 3
Copyright © 2014 Rockwell Automation, Inc. All Rights Reserved. 23
16 Axis Star, Linear K6500, Stratix 8000 Switch 16 Axis Star, K350, Stratix 2000 Switch
So what do these numbers really mean?
Average System Clock Jitter (Max) ~ 35 nanoseconds
0.000000035s x 6000 RPM/ 60s/min = 0.0000035 Revs
Note: Sample from Axis 2
Average System Clock Jitter (Max) ~ 1.8 microseconds
0.0000018s x 6000 RPM/ 60s/min = 0.00018Revs
Note: Sample from Axis 1, off switch 1
Multiply your application speed by this value to determine position error due to network jitter
Copyright © 2014 Rockwell Automation, Inc. All Rights Reserved.
PUBLIC INFORMATION
Maximizing Machine PerformanceTopology Design Considerations
Copyright © 2014 Rockwell Automation, Inc. All Rights Reserved.
What’s new since last year?
A year’s worth of new testing has been completed The latest products have been tested
3 Key Performance Indicators Tracking Error Registration Time Skew Registration Position Skew
More data to back up our previous recommendations Specific cell-based automation network guidelines intended for
performance
Copyright © 2014 Rockwell Automation, Inc. All Rights Reserved.
Topology #1Baseline Topology
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Point I/O™ Adapters ArmorBlock™ I/OKinetix® 5500 or
Kinetix 6500 Drives
PowerFlex Drives
PanelView™ Plus
Plant Network
(Any)Switch
CIP Encoders
Metric 0% Load 20% Load 40% Load
Tracking
RegPos
RegTime
CompactLogix™ L36ERM
Switch Topology QoS PTP
Embedded Linear Direct Yes Yes
(16) axes were tested in this topology
Copyright © 2014 Rockwell Automation, Inc. All Rights Reserved.
Topology #2: Linear InterposingUnmanaged (No QoS, No PTP)
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CMX L36ERM
Plant Network
Stratix 2000
PanelView Plus
Point I/O Adapters ArmorBlock I/OKinetix 5500 or
Kinetix 6500 Drives
CIP Encoders
PowerFlex® Drives
Metric 0% Load 20% Load 40% Load
Tracking
RegPos
RegTime
Switch Topology QoS PTP
Stratix 2000 Star/Linear No No
(16) axes were tested in this topology
Copyright © 2014 Rockwell Automation, Inc. All Rights Reserved.
Topology #2a: Linear DirectUnmanaged (QoS, PTP in place)
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Plant Network
Stratix 2000
PanelView Plus
Point I/O Adapters ArmorBlock I/OKinetix 5500 or
Kinetix 6500 Drives
CIP Encoders
PowerFlex Drives
CMX L36ERM
Switch Topology QoS PTP
Embedded Linear Direct Yes Yes
(16) axes were tested in this topology
Metric 0% Load 20% Load 40% Load
Tracking
RegPos
RegTime
Copyright © 2014 Rockwell Automation, Inc. All Rights Reserved.
Topology #3: Linear InterposingLow-Level Managed (No QoS, No PTP)
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PanelView Plus
Plant Network
Stratix 5700 Lite
Point I/O Adapters ArmorBlock I/OKinetix 5500 or
Kinetix 6500 Drives
PowerFlex Drives
CMX L36ERM
Switch Topology QoS PTP
Stratix 5700 Lite Star/Linear No No
CIP Encoders
(16) axes were tested in this topology
Metric 0% Load 20% Load 40% Load
Tracking
RegPos
RegTime
Copyright © 2014 Rockwell Automation, Inc. All Rights Reserved.
Topology #3a: Linear DirectLow-Level Managed (QoS, PTP in place)
34
PanelView Plus
Plant Network
Stratix5700™
Lite
Point I/O Adapters ArmorBlock I/OKinetix 5500 or
Kinetix 6500 Drives
PowerFlex Drives
CIP Encoders
CMX L36ERM
Switch Topology QoS PTP
Embedded Linear Direct Yes Yes
(16) axes were tested in this topology
Metric 0% Load 20% Load 40% Load
Tracking
RegPos
RegTime
Copyright © 2014 Rockwell Automation, Inc. All Rights Reserved.
Topology #4: Linear InterposingMid-Level Managed (QoS, No PTP)
35
PanelView Plus
Plant Network
Point I/O Adapters ArmorBlock I/OKinetix 5500 or
Kinetix 6500 Drives
PowerFlex Drives
Stratix 5700 Full
ControlLogix L36ERM
Metric 0% Load 20% Load 40% Load
Tracking
RegPos
RegTime
Switch Topology QoS PTP
Stratix 5700 Full Star/Linear Yes No
(16) axes were tested in this topology CIP
Encoders
Copyright © 2014 Rockwell Automation, Inc. All Rights Reserved.
Topology #4a: Linear DirectMid-Level Managed (QoS, PTP in place)
36
PanelView Plus
Plant Network
Point I/O AdaptersKinetix 5500 or
Kinetix 6500 Drives
PowerFlex Drives
Stratix 5700 Full
CIP Encoders
ArmorBlock I/O
ControlLogix L36ERM
Switch Topology QoS PTP
Embedded Linear Direct Yes Yes
(16) axes were tested in this topology
Metric 0% Load 20% Load 40% Load
Tracking
RegPos
RegTime
Copyright © 2014 Rockwell Automation, Inc. All Rights Reserved.
Topology #5: Linear InterposingFully Managed (QoS and PTP)
37
PanelView Plus
Plant Network
Stratix 5700
Full/PTP
PowerFlex Drives
Point I/O AdaptersKinetix 5500 or
Kinetix 6500 Drives
CIP Encoders
ArmorBlock I/O
CMX L36ERM
Switch Topology QoS PTP
Stratix 5700 Full/PTP Star/Linear Yes Yes
(16) axes were tested in this topology
Metric 0% Load 20% Load 40% Load
Tracking
RegPos
RegTime
Copyright © 2014 Rockwell Automation, Inc. All Rights Reserved.
Topology #6: STAR InterposingFully Managed (QoS and PTP)
38
PanelView Plus
Plant NetworkPowerFlex
Drives
Point I/O Adapters
CIP Encoders
ArmorBlock I/O
Stratix 5700
Full/PTP
ControlLogix L36ERM
Switch Topology QoS PTP
Stratix 5700 Full/PTP Star Yes Yes
Kinetix 5500 orKinetix 6500 Drives
(8) axes were tested in this
topology
Metric 0% Load 20% Load 40% Load
Tracking
RegPos
RegTime
Copyright © 2014 Rockwell Automation, Inc. All Rights Reserved.
Topology #7: STAR InterposingMid-Level Managed (QoS, No PTP)
PanelView Plus
Plant NetworkPowerFlex
Drives
Point I/O Adapters ArmorBlock I/O
Stratix 5700 Full
39
Switch Topology QoS PTP
Stratix 5700 Full Star Yes No
CIP Encoders
Kinetix 5500 orKinetix 6500 Drives
Metric 0% Load 20% Load 40% Load
Tracking
RegPos
RegTime
CIP Encoders
Did not test beyond (8) axes in this
topology
ControlLogix L36ERM
Copyright © 2014 Rockwell Automation, Inc. All Rights Reserved.
Lessons Learned/Confirmed
40
For devices that include an embedded Ethernet switch: Connect these devices directly to a controller (GM) when possible
without an interposing switch Use a PTP-capable switch if connected between GM and PTP-
sensitive devices Place any non-PTP capable switches at the end of the line of
embedded switch products
Stratix 5700
Full/PTP Any Switch
Copyright © 2014 Rockwell Automation, Inc. All Rights Reserved.
Lessons Learned/Confirmed
41
For single-port Ethernet products (like Kinetix 350 drives): For 1-4 axes, offer a Stratix 2000 unmanaged switch* For 5-8 axes, offer a Stratix 5700 Full managed switch* Over 8 axes, offer a Stratix 5700 Full (PTP) managed switch Use 1783-ETAP devices for ring topologies with Kinetix 350 drives
* The application must not be marginal in terms of dynamics and accuracy requirements
Stratix 2000
Kinetix 350 Drives
Single Switch; no cascading
ControlLogixL36ERM
(4) axes were tested in this topology
Copyright © 2014 Rockwell Automation, Inc. All Rights Reserved.
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Copyright © 2014 Rockwell Automation, Inc. All Rights Reserved.
PUBLIC INFORMATION
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