LonWorks PLC

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LonWorks PLC

• (c) 2013 R. Newman
• University of Florida

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What is LonWorks Protocol

• Multiple medium protocol for home automation
  (domotics) and control
• Local Operating Network (LON)
• Narrowband PLC, TP, CX, fiber optics, RF
• TP 78 kbps using Differential Manchester
• PLC 5.4 or 3.6 kbps depending on frequency band
• Developed by Echelon Corp.
• 60 million devices by 2006
• Multiple standards
• International and open industry standard
• European standards
• China national standards

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LonWorks Standards

• International and open industry standard
• Submitted to ANSI 1999 - ANSI/CEA-709.1
• Basis for IEEE 1473-L (in-train controls)
• SEMI (semiconductor equipment manufacturing)
• One of several data link/physical layers of the
  BACnet ASHRAE/ANSI standard for building
  automation.
• ISO and IEC standards ISO/IEC 14908-1, -2, -3,
  and -4 (communications protocol, twisted pair
  signaling technology, power line signaling
  technology, and Internet Protocol (IP)
  compatibility)
• European standards
• AAR electro-pneumatic braking systems for freight
  trains
• IFSF (European petrol station control)
• EN 14908 (European building automation standard)
• Part of Household Appliances Control and
  Monitoring Application Interworking
  Specification (AIS) standards of CECED (European
  Committee of Domestic Equipment Manufacturers)
• China national standards
• Controls standard, GB/Z 20177.1-2006
• Building and intelligent community standard, GB/T
  20299.4-2006

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LonWorks Major Elements

• LonTalk protocol
• Neuron chips
• LonWorks transceivers
• Network management/applications
• SNVTs (Standard Network Variable Types)

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LonTalk Protocol

• Media
• Twisted pair, powerline, radio frequency, fiber
  optics, coaxial cable
• Highest data rate 1.2 Mbps
• Reliability
• Supports end-to-end acks with ARQ
• Broadcast acks also
• Medium access
• Proprietary collision prediction algorithm
• Collision detection on some media (e.g., TP)
• Optional priority feature
• Network management/applications
• SNVTs

ACK implosion problem!
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LonTalk Addressing

• Hierarchical
• Domain, subnet, node also Group
• All nodes in domain, subnet addressable
• Channel physical medium
• Domain logical set of nodes on one or more
  channels
• Communication only possible in domain
• Multiple domains may share channel(s)
• Subnet must share a channel
• cannot span a router, 127 node max
• Domain may have up to 255 subnets
• Group may use multiple channels
• Node may be in up to 15 groups, lt64 nodes/group
• Domain may have up to 255 groups

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LonTalk Delivery Services

• Unacknowledged
• Most commonly used
• Widest bandwidth
• Unacknowledged/Repeated
• No acks, but multiple copies sent per settings
• Acknowledged
• Used when reliability required
• Timeout set at installation time
• Priority
• Time slots may be set aside for priority traffic
• Used sparingly reduces bandwidth available

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LonTalk Network Management

• All nodes are network management capable
• Find unconfigured nodes and download network
  addresses.
• Stop, start and reset node applications
• Configure routers and bridges
• Download new application programs
• Change the network variable configuration table
• type of protocol service used to send the network
  variable
• whether the variable is sent in a priority slot.

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LonWorks Transceivers

• Twisted Pair
• 78 Kbps/4600 ft (1400 m)
• 1.25 Mbps/430 ft (130 m)
• Powerline
• Spread spectrum (proprietary) or narrowband
• 10 Kbps, Up to 2000 m on clear line
• Radio Frequency
• 400-470 MHz licensed
• 900 MHz unlicensed
• Configuration
• Installation announces devices presence
• Binding network variable tells device what data
  to share with whom

Longer distance gt more attenuation gt lower SNR
(noise is constant) gt lower data rate (Shannon's
Thm)
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LonWorks Datalink Layer

• Error Detection (CRC)
• Flexible allocation of bandwidth
• Priority access mechanisms
• Graceful behavior under overload
• p-persistent CSMA
• Message collision avoidance
• Optional collision resolution, collision
  detection

CSMA When current transmission
done p-persistence Tx with prob. p Optimal p is
1/N for N contenders
CD not possible on RF or PLC medium gt Collision
avoidance important
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LonWorks Network Layer

• Node address information
• Message routing to segment
• determining which nodes on the network receive
  various messages
• Network bandwidth usage control
• Routers
• segment traffic
• communicate between different channels

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LonWorks Transport Layer

• Broadcast addressing
• Unicast addressing
• Multicast addressing - groups
• Repeated service
• Acknowledged service
• Unacknowledged service
• Duplicate packet detection
• Authentication

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LonWorks Session Layer

• Acknowledgment of received message
• Application-to-application communication
• Retry if the correct response is not received
  from the remote node
• Request to a destination group and receive
  individual responses from the group
• Request - response message authentication

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LonWorks Presentation Layer

• Input, output, and configuration variables for
  the node
• Standard data representations for physical
  quantities
• Network variable description

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LonWorks Application Layer

• Memory storage for application program
• Built-in real-time operating system
• Device drivers for the I/O hardware on the Neuron
  Chip
• Standard Network Variable Types (SNVTs)

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SNVTs

• Standard Network Variable Types
• A key to interoperability
• Standardizes variables used to name and describe
  things and their states
• Maintained by LonMark International
• Each standard known as an SNVT
• Pronounced snivit
• E.g., temperature is a 16-bit quantity
  representing -274 to 6279.5 Celcius

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SNVT Examples

• Variable Type Units
• Temperature Degrees Celsius
• Real Time MM,DD,YYYY
• Event Count Counts
• of Full Scale Percent
• Volume Gallons, CCF, liters
• Flow Gal or liters/hour
• Weight Kilograms, Lbs.
• Speed Miles or Km/hour
• Alphanumeric ASCII Characters
• Alphanumeric Kanji Characters

Variable Type Units Switch State Boolean Device
State Boolean Energy Kilowatt-Hours Power Watts
Voltage DC or AC RMS Current Amps AC,
RMS Resistance Ohms Sound Level dBrnc Voltage dB
microvolts
Alphanumeric International characters Day of
Week Enumerated List (Mon-Sun) Elapsed
Time Second, Milliseconds, Days or Hours Phone
State Enumerated List (On-hook, off-hook, busy,
ringing, etc.) PressureLbs./sq.in, Pascals,
Inches-Hg Relative Humidity Percent
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LonWorks Links

• http//www.ieclon.com/LonWorks/LonWorksTutorial.ht
  ml