ANSI/CEA709 (EN14908) Standards

August 2006

04H1122

Vijay Dhingra

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Data networks interconnect computers, servers, and printers Control networks connect sensors, actuators, displays, and other

machines to each other, to remote monitoring sites, and to the Internet– All control networks perform a common set of functions: they sense,

process, actuate, and communicate

Internet

Background

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Control Network Technology Requirements

Robust, reliable communications – Peer-to-peer protocol supports multiple media, efficient

addressing and authentication – No single point of failure in the control system– Predictable, autonomous applications regardless of

network traffic Open standards based and Interoperable products Large Ecosystem of cost effective solution

– Best of breed products in commercial and home market Confidence and leverage in a future proof environment

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Multiple Media Support

Control applications require flexibility in selecting communication medium– Protocol and routing technology that allows multiple

media (Mixed as needed within system): Power line Twisted pair Fiber optic RF Coaxial cable Infrared IP

Interface with other home networking standards/protocols– With simple application layer bridging

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LONWORKS Control Networks

Flat Peer-Peer Network Architecture– Eliminate complex cabling– Lower installation and maintenance costs– Eliminate proprietary & closed gateways, and central

controllers– Simplify HMI development

Open– Choose interoperable components from multiple vendors

ANSI/CEA-709.1-BControl Networking Protocol

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ANSI/CEA-709.1-B Protocol

An open standard protocol for control applications– Control applications have different requirements than data

applications– TCP/IP is an example of a data networking protocol– Reference document available from Global Engineering

Protocol implementations are available from multiple vendors– Protocol can be ported to any processor – Echelon’s implementation is called the LonTalk® protocol– Echelon’s Neuron® firmware includes the LonTalk protocol– Echelon development systems include a royalty-free unlimited

license to use the Neuron firmware implementation

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ANSI/CEA-709.1 Protocol Layers

ANSI/CEA-709.1 is layered– As recommended by the International Standards

Organization Open Systems Interconnect (ISO OSI) reference model

– OSI layers ensure that the required services are provided without unexpected interactions between the services

– Device manufacturers only need to change the application

Application

Presentation

Session

Transport

Network

Data Link

Physical

Physical MediaPhysical Media

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ANSI/CEA-709.1 Protocol Layers

OSI Layer Purpose Services Provided

7 Application Application Compatibility Network Configuration; Network Diagnostics; File Transfer; Application Configuration, Specification, Diagnostics, & Management; Alarming; Data Logging; Scheduling;Time & Date Management

6 Presentation Data Interpretation Network Variables; Application Messages; Foreign Frame Transmission; Standard Types

5 Session Control Request-Response; Authentication

4 Transport End-to-End Reliability Acknowledged & Unacknowledged Message Delivery; Duplicate Detection

3 Network Message Delivery Unicast & Multicast Addressing; Routers

2 Link Media Access and Framing Framing; Data Encoding; CRC Error Checking; Predictive CSMA; Collision Avoidance; Priority & Collision Detection

1 Physical Electrical Interconnect Media-Specific Interfaces and Modulation Schemes (twisted pair, power line, radio frequency, coaxial cable,

infrared, fiber optic)

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A Typical ANSI/CEA-709.1 Packet

BacklogPriorityAlt Path

12 Bytes

Layer 2Header

Layer 3Address Information

Layer 4Service Type

Layer 5/ 6Header

Layer 2 CRC

DATA

Addr Format, Domain Length

Source Addr (Subnet/Node)

Dest Addr (Group)

Domain ID (Zero Len Domain)

Service Type IDTransaction Num

Network VariableSelector

2 BytesUnsigned

Long 2 Bytes

2 Bytes

1 Byte

1 Byte

1 Byte

2 Bytes

1 Byte

0 Bytes

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Layer 1—Physical Layer

Electrical interconnect– Transmission of raw bits over a communication channel

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Physical Layer—Common Channel Types

Name Media Bit Rate Definition StandardDC-1250 Direct-Connect Twisted Pair 1.25Mbps Neuron Chip Data Book No

FO-20L Fiber Optic 1.25Mbps ANSI/CEA-709.4 YesFO-20S Fiber Optic 1.25Mbps ANSI/CEA-709.4 YesIP-852 ANSI/CEA-852 IP

TunnelingN/A ANSI/CEA-852 Yes

PL-20A CENELEC A-band Power Line

2613bps LONMARK Interoperability Guidelines

Yes

PL-20C CENELEC C-band Power Line w/access protocol

156.3k/3987bps ANSI/CEA-709.2 Yes

PL-20N CENELEC C-band Power Line w/o access protocol

156.3k/3987bps ANSI/CEA-709.2 Yes

TP/FT-10 Free Topology Twisted Pair 78.13kbps ANSI/CEA-709.3 Yes

TP/RS485-39 RS-485 Twisted Pair 39.06kbps EIA/TIA-232-E Yes

TP/XF-1250 Transformer-Isolated Twisted Pair

1.25Mbps LONMARK Interoperability Guidelines

Yes

Optimize cost and performance for a broad range of control applications

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Typical Channel Capacities

PL-20x Channels– PL-20N ~20 packets/sec– PL-20C ~18 packets/sec– PL-20A ~11packets/sec

TP/FT-10 Channel– Peak: ~225 packets/sec– Sustained: ~180 packets/sec

TP/XF-1250 Channel– Peak: ~720 packets/sec– Sustained: ~576 packets/sec

IP-852 Channels– ~10,000 packets/sec– Supports aggregation

TP/FT-10

TP/XF-1250

PL-20x

IP-852

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Physical Layer—TP/FT-10 Channel

Defined by ANSI/CEA-709.3-A Free-Topology Twisted Pair Channel Specification Media is free topology twisted pair with optional link power

– Supports commonly available unshielded and shielded 0.50mm (24AWG) to 1.3mm (16AWG) twisted pair wires

– Polarity insensitive wiring– Reduces installation and maintenance costs

Up to 64 devices on a single network segment– Or 128 devices along with a link power source

Available in cost-effective device-on-a-chip– With all-in-one transceiver, application processor, and memory

Singly-Terminated Bus Topology

Star Topology

Loop Topology

Mixed Topology

= Termination

Doubly-Terminated Bus Topology

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Physical Layer—PL-20 Channel

Advanced technology for reliable communication– Dual carrier frequency operation – Digital signal processing

Worldwide operation– Meets FCC, Industry Canada, Japan MPT, and

European CENELEC EN50065-1 regulations regulations

– ANSI/CEA-709.2 compliant European utility support

– Dual frequency DSP performance in the A-Band for AMR/DSM applications

Available in cost-effective device-on-a-chip– Transceiver, application processor, memory

Proven technology– Millions of devices installed worldwide

A-Band75kHz 86kHz

115kHz 132kHzC-Band

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Layer 2—Link Layer

Media access and framing– Ensures efficient use of a single communications channel – Raw bits of the physical layer are broken up into data

frames– Link layer defines when a device can transmit a data frame – Also defines how destination devices receive the data

frames and detect transmission errors Features

– CRC error checking – Media access—predictive p-persistent CSMA– Priority– Collision avoidance

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Link Layer—Media Access

Predictive p-persistent CSMA Channel access is always

randomized over time slots Number of time slots are varied

based on collision avoidance algorithm– 16 to 1008 slots

Non-priority Slots

Packet Packet

Busy Channel Packet Cycle

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Link Layer—Media Access Priority

Configurable priority messages– Reserved time slot– Reduces overall channel bandwidth

Priority slot number is assigned at installation time

No collisions possible during priority portion of packet cycle following preceding packet

Highest priority message has predictable response time

Packet Packet1 2 3 n...

Priority Slots

Busy Channel Packet Cycle

Non-priority Slots

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Link Layer—Media Access Benefits

Linear response time over 99% of channel bandwidth– Critical for open media such as power line

Remove and attach devices without halting communications Predictable performance for high-priority messages

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Link Layer—709.1 MAC vs. Ethernet

from: Computer Networks, Andrew S. Tanenbaum, Fourth Edition, 2003.

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Layer 3—Network Layer

Message delivery– How data frames are routed from a

source device to one or more destination devices

Physical address– 48-bit Neuron ID—used for initial

configuration Logical addresses

– Domain Identifies subsystem on open media or large system

– Subnet Subset of a domain typically associated with a channel

– Node Identifies device within subnet– Group Additional device identifiers

independent of subnet

1271 SUBNET 1

1271 SUBNET 2

1271 SUBNET 3

1271 SUBNET 4

1271 SUBNET 255

GROUP 1

DOMAIN (32,385 Devices)

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Network Layer—Addressing Modes

Address Mode Address Format Destination Address Size

(bytes)

Domain-wide Broadcast

Domain (Subnet = 0) All devices inthe domain

3

Subnet-wide Broadcast Domain, Subnet All devices inthe subnet

3

Unicast Domain, Subnet, Node

Specific devicewithin a subnet

4

Multicast Domain, Group All devices inthe group

3

Neuron ID Domain, Neuron-ID Specific device 9

Optimize bandwidth with multiple addressing modes Application communications only requires 3- or 4-byte network

addresses Send messages to many devices using only a single 3-byte network

address

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Network Layer—Capacity

18,446,744,073,726,329,086 domains 255 subnets per domain 127 devices per subnet 32,385 devices per domain 256 groups per domain 64 devices per acknowledged group 32,385 devices per unacknowledged group

Room to grow from a few devices to millions

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Network Layer—Routers

Extend channel segments Improve reliability Increase overall bandwidth Simplify network configuration

– Routers are transparent to devices and applications

Domain

...

RepeaterRouter

Channel

Router

Group 1

Subnet 1

RepeaterRouter

Subnet 2

Subnet 3

Subnet 4

Subnet 1

Subnet 5

Group 1

Group 2

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Layer 4—Transport Layer

End-to-end reliability—allows reliable delivery of message packets

Three message delivery services– Acknowledged

Sending device requires acknowledgment from all receiving devices

All acknowledgments are end-to-end Automatic retries if acknowledgement not received

– Repeated Configurable number of messages per transaction Conserves bandwidth with large groups Better response time Three repeats provides > 99.999% probability of delivery

– Unacknowledged One message per transaction Conserves network bandwidth and provides highest performance

Duplicate detection prevents repeated messages to the application

S R

S RRRR

S

S R

Acknowledged - Unicast

Acknowledged - Multicast

Repeated- Unicast or Multicast

Unacknowledged - Unicast or Multicast

R

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Layer 5—Session Layer

Adds control to the data exchanged by the lower layers

Request/response service– Used for device management, fetching

values, and requesting other remote actions

Authentication– Verifies identity of message sender…

S R

SRRR

R

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Session Layer—Authentication

Verifies identity of message sender Uses a 48-bit secret key known by each device Sender must provide correct reply to 64-bit random

challenge from the receiver

Sender ReceiverAuthenticated Message

64 bit Random Challenge

Key used to transform challenge

Challenge Response

Key used to compare response to value transformed locally.

Acknowledgment

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Room Temp

Set Point

Temp

Set Point

Temp Sensor(Made in USA)

Setpoint Display(Made in Korea)

Boiler System(Made in Europe)

Layer 6—Presentation Layer

Data exchanged using network variables– Propagation automatically handled by Neuron firmware– Provides fastest and most compact code

Devices from different manufacturers can exchange data with a common interpretation

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Presentation Layer—Connections

Sensors “publish” information, and actuators “subscribe” to information Devices are logically connected Connections do not affect device applications

Motion Detector

Key Pad

Control Knob

0% - 100%

Motion

Lamp

Brightness

Room Occupied

Alarm Bell

Key Code

Feedback

AlarmArm / Disarm

Intruder

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Presentation Layer—Standard Types Standard network variable types

– Over 170 standard types defined at types.LONMARK.org– XML definitions available for easy input/translation/interpretation by other

systems

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Presentation Layer—Standard Formatting

Ensures consistent data presentation in tools and HMIs Example

– A SNVT_temp_p value of 2940 is displayed as follows:

29.4 degrees C

84.9 degrees F

52.9 degrees F

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Layer 7—Application Layer

Defines standard network services that use data exchanged by the lower layers – Network configuration and diagnostics– File transfer– Application configuration, diagnostics, management, and

specification– Standard profiles

Alarming Data logging Scheduling More than 60 others

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Application Layer—Application Configuration

Configuration properties characterize the behavior of a device in the system – Types define data encoding, scaling, units, default value, range, and behavior– Standard configuration property types defined at types.LONMARK.org– XML definitions available for easy input/translation/interpretation by other

systems

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Application Layer—Application Specification

Functional block– Portion of a device’s application

that performs a task – Receives configuration and

operational data inputs– Processes the data– Sends operational data outputs

Node Object

Mandatory Network Variables

Configuration Properties

Optional Network Variables

nvoStatusSNVT_obj_status

nv2

nvoAlarm2SNVT_alarm_2

nv10

nvoDateResyncSNVT_switch

nv11

nvoAlarmSNVT_alarm

nv4

nvoFileStatSNVT_file_status

nv6

nvoFileDirectorySNVT_address

nv8

nviRequestSNVT_obj_request

nv1

nviTimeSetSNVT_time_stamp

nv3

nviDateEventSNVT_date_event

nv9

nviFileReqSNVT_file_req

nv5

nviFilePosSNVT_file_pos

nv7

nvoLogStatSNVT_log_status

nv13nviLogReqSNVT_log_req

nv12

Mandatory OptionalDevice Major VersionDevice Minor VersionFunctional Block Major VersionFunctional Block Minor VersionLocationMaximum Status Send TimeMinimum Send Time (Send Throttle)Network Configuration Source

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Application Layer—Standard Profiles