enhancements to single-pair ethernet for constrained devices … · 2020-05-20 · new...

Enhancements to Single-pair Ethernet for Constrained Devices David D. Brandt: Rockwell Automation, Inc. Chirag Malkan: Rockwell Automation, Inc. Tony Wang: Rockwell Automation, Inc. Jeff Martin: Rockwell Automation, Inc. March 4, 2020

Purpose of Paper

2

Industrial Ethernet has exhibited rapid growth, with EtherNet/IP emerging as a leader in the “Internet of Things” movement. This paper presents set of operational concepts driving successful EtherNet/IP deployment to many low-end/constrained “Things” (such as contactors and push buttons) thus enabling the single-network vision - where all devices in an industrial plant can communicate with the same set of protocols, while balancing node cost, node size, and ease of commissioning the smart system.

Technical Track 2020 Industry Conference & 20th Annual Meeting www.odva.org © 2020 ODVA, Inc. All rights reserved.

Industrial Network Convergence

4

Industrial Network Convergence


Industrial Ethernet has exhibited rapid growth, with EtherNet/IP emerging as a leader.

Fieldbuses (and sensor networks) still retain a large position and many potential network nodes remain hardwired.

Source: HMS, May 2019 (Parentheses indicate 2018 numbers)

The Single Network Vision

5

§  Single network advantages include: §  Higher performance for a similar cost §  Elimination of costly application-level

gateways §  Leverage of a large existing

ecosystem (protocols, security, network switches, etc.)

§  Reduced installation, maintenance, and management complexity

§  Simplified integration with cloud applications

§  Reduced interoperability issues


End users understand and seek the advantages of a harmonized network - based on Ethernet, Internet Protocol,

and the related open ecosystem.

APL!

OPEN!Alliance! Digital!

Ceiling!

IEEE! IETF!

Organizations promoting Ethernet!and Internet Protocol to the edge!

6

IEEE Single Pair Ethernet(s)


Automotive!

Industrial Automation!

Building Automation!

Lighting!

Elevators!

Data Center!

IEEE 802.3cg!Numerous industries sought Ethernet enhancements to displace edge networks.

•  Communication and optional power over a single pair

•  Reduction in wiring, node cost, size, and power consumption

Recently Published IEEE SPE Standard

7

§  IEEE Std 802.3cg-2019 (10 Mbit/s SPE PHYs) §  10BASE-T1L

§  Targeted at Process Automation instruments §  1000 m, intrinsic safety compatible, legacy wiring

§  10BASE-T1S §  Targeted at replacing:

§  CAN, CAN FD, MOST and FlexRay in Automotive §  Hardwiring for in-cabinet components for Industrial Automation §  I2C and SPI in Data Centers

§  25 m multidrop option §  Determinism by PHY-level Collision Avoidance (PLCA)

Addresses long distance

Addresses low cost control


Constrained EtherNet/IP application areas

PAC/PLC/DCS PAC/PLC/DCS Basic Control

PAC/PLC/DCS Supervisory Control

Automa9on Servers

Manufacturing Systems

Enterprise Systems

Field Devices Constraints

IT, Cloud

PAC/PLC/DCS PAC/PLC/DCS

In-‐cabinet On-‐machine Process Automa4on Low-‐power Wireless

100BASE-‐TX and 1000BASE-‐T 10BASE-‐T1S mul9-‐drop TBD SPE 10BASE-‐T1L, 1000m, Ex e 10BASE-‐T1L, 200m, Ex i

Cost, size, power

BaKery, packet size, rate

Intrinsic safety, power

Power vs. cable size & length

#wires, size, power

6TiSCH + 802.15.4e

8 Technical Track 2020 Industry Conference & 20th Annual Meeting www.odva.org © 2020 ODVA, Inc. All rights reserved.

Single-pair Ethernet for Constrained In-Cabinet Devices

10

Constrained In-Cabinet Devices Problem Space


•  Hundreds of wires in a typical customer application !•  Hardwired with limited intelligent information!

Imagine how many wires are needed if there are multiple motor starters and pilot devices!

11

Constrained In-Cabinet Devices Customer Requirements Extensive customer listening sessions resulted in the following key requirements for the Constrained EtherNet/IP Devices: •  It must be Economical

–  It must use low cost media –  It must allow for a reduction in price and size of typical products –  It must allow the use of commercial off-the-shelf power supplies –  It must result in a lower “total cost of ownership” than hard wired solutions

•  It must be Simple to use

–  It must use a single easy to use media connector –  It must include a simple (or no) network commissioning methodology –  It must eliminate the need for media trunk and drop distance calculations

•  Just Enough Functionality –  It must simplify in-cabinet wiring for panel builders –  It must deliver both Network Power to power device electronics and Switched (Control) Power to facilitate the

actuation of Contactors and Relays –  It must support Non-Safety and Safety devices on the same wire


Single Pair Ethernet for Constrained In-Cabinet Devices

12

10BASE-T1S Technology Key Characteristics

Low Power ~250 mW • Lower Cost • Constrained

Ethernet (UDP-only stack) • 10 Mbps half-duplex •

Multi-conductor cable • 25 meter cable length •

Multi-Drop • IEEE Std 802.3cg-2019 10BASE-T1S


Technical Architecture for Constrained In-Cabinet Devices

13

Technical Arch •  Multi-conductor flat cable connecting multiple devices delivers power and enables 10BASE-T1S communication in a multi-drop Topology. •  The overall system is powered by a 24VDC power supply. There are two power channels defined: NP (Network Power) and SP

(Switched Power). NP power is used to power the communication circuit of the whole network. SP power is utilized for all the Output loads (contactor control coil, sounder, etc.)

•  Gateway provides power for both NP and SP channels and links In-Cabinet devices to 4-pair Ethernet. •  SP Tap is required to inject new SP power to the system when Gateway is not capable of providing SP power for all the loads.


Gateway w Terminator

SP Tap SP Tap

Network Power

Switched Power 1 Switched Power 2 Switched Power 3

Terminator

Proposed Timeframe

Constrained EtherNet/IP Media for In-cabinet Application

SPE 10Base-T1S Multidrop Cable


17

•  7 Conductors –  Network Power to power device electronics –  Switched (Control) Power to actuate contactor coils –  SPE Signal Pair for T1S based PLCA Mul9drop Ethernet Communica9on –  Select Line for simple sequen9al network service delivery to discover linear nodal topology.

•  20AWG wires (19 strands) for NP-‐, NP+, SP+, SP-‐ •  24AWG wires (7 strands) for SPE+, SPE-‐, Select Line •  > 4A desired (NP-‐, NP+, SP+, SP-‐) •  SPE data pair conductors and increased Select Line spacing will be used as keying feature to

minimize chance of wrong connector orienta9on.

SPE 10Base-T1S Multidrop Media Interface


18 18

•  Connector shall be connected to and make an electrical connec9on with the media using standard or no tools •  Connector shall break the Select line and then establish connec9ons to Select_A and Select_B pins •  Connector may break both SPE+ and SPE-‐ lines and add inline inductors for improved signal integrity.

SPE 10Base-T1S PHY Requirements


19 19

RS MAC

PCS PMA PMD

MII

PHY with MII

MCU with MAC

Core + Memory + Peripherals

Not Preferred: not cost and size optimized

RS MAC

PCS PMA PMD

SPI

MAC PHY with SPI

MCU Core + Memory + Peripherals

Preferred: low cost and small size

RS MAC

PCS PMA PMD

MCU with MAC and PHY PHY

Core + Memory + Peripherals

Best: lowest cost and smallest size

SPE 10Base-T1S Multidrop Media and Hardware


20 20

Cable Sample: Impedance at 104ohm, Inser9on loss of 6.7dB @40MHz for 25 meter Connector Sample: Inser9on loss of 0.1dB@40MHZ return loss of 33dB@40MHz, Breaking both SPE+ and SPE-‐ lines ,36nH in-‐line inductors are built in. T1S Hardware: Evalua9on boards with T1S PHY compliant to IEEE 802.3CG drag 2.1 MII Interface Integrated PLCA func9ons !

SPE 10Base-T1S Multidrop Media and Hardware


21 21

•  Mul9ple setups were evaluated to determine the number of nodes that can be supported with T1S hardware, cable and connectors.

•  40 total nodes; master node 0 at the beginning of 25meter cable, node 1 in the middle of the cable, 38 nodes lumped at the end of the 25meter cable

•  Conducted BER test with no bit errors. •  Measured eye height at nodes and matched simula9on results.

Node 39

Constrained EtherNet/IP Communication Profile and Stack Summary

23

Constrained EtherNet/IP Communication Profile •  Problem:

–  EtherNet/IP does not support constrained device and network requirements

•  Solution: –  Develop a constrained EtherNet/IP

communication profile

Required: •  UDP-only •  Minimum objects •  UCMM and Class 1 only •  Simplified Connection

Manager object Optional:

•  DTLS-only security •  Class 2/3 over UDP •  IPv6 mapping

Communication Profile!


24

Minimum device object model •  Same base objects for constrained

EtherNet/IP, but minimize implementation of base objects

•  Minimized CIP transports over UDP

–  UCMM + Class 1 only


Object minimization example - Connection Manager

25

Original Defini4on in EtherNet/IP Specifica4on

Simplified Implementa4on for Constrained Devices

Object level simplifica9ons

20 op9onal aKributes Zero aKributes

4 common services Zero common services

8 object specific services 2 object specific services (Forward_Open and Forward_Close)

Service level simplifica9ons

Class 0 and 1 I/O connec9on Class 1 I/O connec9on

Unicast and mul9cast Unicast

Class 2 and 3 explicit connec9on No explicit connec9on, UCMM only

CIP Rou9ng No CIP Rou9ng

Listen-‐only or redundant owner No redundancy


26

UDP-only option •  Problem:

–  EtherNet/IP requires both TCP and UDP

–  TCP presents substantial overhead for constrained MCU limited Flash and RAM

–  “Chatty” TCP messaging reduces battery life in low power wireless devices

•  Related Problem: –  CIP Security requires both TLS and

DTLS

•  Solution: –  Add optional support

for UDP-only and DTLS-only.

•  Benefits: –  Use smallest MCUs

•  UDP-only prototype shows 30% savings in Flash and RAM

–  Draw enhancements from other sources

•  Emerging IoT stacks like IETF CoAP rely on UDP exclusively

DTLS

UDP

TLS

TCP


EtherNet/IP Capability CPF Item

27

•  New “EtherNet/IP Capability” CPF item

–  Discover device’s EtherNet/IP capability using ListIdentity

•  New EDS entry [ApplicationProfilesAssembly]

–  Describe device’s EtherNet/IP Capability

Field

Type ID EtherNet/IP Capability (0x87)

Length Number of bytes = 4

EtherNet/IP Transports Applica9on Profile

Bit 0 = UCMM over TCP Bit 1 = UCMM over UDP Bit 2 =Class 3 Connec9ons via TCP Bit 3 = Class 3 Connec9ons via UDP Bit 4 = Class 2 Connec9ons via TCP Bit 5 = Class 2 Connec9ons via UDP Bit 6 = Class 1 Connec9ons Bit 7 = Class 0 Connec9ons


Transports Application Profile Allowed Features Combinations

28


Features Full EtherNet/IP Transport Profile

UDP-‐Only EtherNet/IP Transport Profile

UCMM over TCP Required Not Supported

UCMM over UDP Not Supported Required

Class 3 over TCP Op9onal Not Supported

Class 3 over UDP Not Supported Op9onal

Class 2 over TCP Op9onal Not Supported

Class 2 over UDP Not Supported Op9onal

Class 1 over UDP Op9onal Op9onal

Class 0 over UDP Op9onal Op9onal

•  Combina9ons of features that may be supported for each Ethernet/IP transport profile !

Simplified UDP-based Messaging


•  ListIdentity identifies capability –  UDP-only or TCP+UDP

or Both •  No TCP connections •  No encapsulation

sessions •  No bindings between

TCP connections and EtherNet/IP sessions

Message and stack

complexity is reduced

Existing EtherNet/IP!Simplified EtherNet/IP!

TCP-based Forward_Open

TCP-based Forward_Close

Constrained EtherNet/IP Stack

30

Eliminated

New

Modified

Unmodified

802.15.4 PHY

802.15.4e MAC

IPv4

10BASE-‐T1L 10BASE-‐T1S

802.3

6TiSCH

2222/UDP

DTLS

2221/UDP 44818/UDP

UDP ENCAP

2221/TCP

TLS

44818/TCP

TCP ENCAP Session

Class3 Class 1 UCMM

Capability CPF

CM

MR AR Objs.

802.15.4

TCP

APP 1 APP 2 APP n

Op9onal aKributes and services, mul9cast, CIP

rou9ng 6T

6LBR Profile

IPv4/6 Mapping

Encap. Header

Modified or new Links

Wireless Wired

EDS

-‐ Capability -‐ 802.15.4 -‐ 6LBR

UDP-‐only

DTLS-‐only

UCMM+CL1 only UCMM

CM: Connec9on Manager Object MR: Message Router Object AR: Ac9ve Report -‐ related Objects TCP: TCP/IP Object EN: Ethernet Link Object 6TiSCH: IPv6 over the TimesloKed Channel Hopping (TSCH) mode of IEEE802.15.4e 6LBR: 6LoWPAN Border Router for 6TiSCH

EN

ListIden9ty ListServices


THANK YOU

Enhancements to Single-pair Ethernet for Constrained Devices Chirag Malkan: Rockwell Automation, Inc. David D. Brandt: Rockwell Automation, Inc. Tony Wang: Rockwell Automation, Inc. Jeff Martin: Rockwell Automation, Inc. March 4, 2020

enhancements to single-pair ethernet for constrained devices … · 2020-05-20 · new...

Documents