LonWorks PLC (c) 2013 R. Newman University of Florida

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

LonWorks Standards International and open industry standard –Submitted to ANSI ANSI/CEA –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.BACnet –ISO and IEC standards ISO/IEC , -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 (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 –Building and intelligent community standard, GB/T

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

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!

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, <64 nodes/group –Domain may have up to 255 groups

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

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.

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 – MHz licensed –900 MHz unlicensed Configuration –Installation announces device’s presence –Binding network variable tells device what data to share with whom Longer distance => more attenuation => lower SNR (noise is constant) => lower data rate (Shannon's Thm)

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 => Collision avoidance important

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

LonWorks Transport Layer Broadcast addressing Unicast addressing Multicast addressing - groups Repeated service Acknowledged service Unacknowledged service Duplicate packet detection Authentication

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

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

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)

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 Celcius

SNVT Examples Variable TypeUnits TemperatureDegrees Celsius Real TimeMM,DD,YYYY Event CountCounts % of Full ScalePercent VolumeGallons, CCF, liters FlowGal or liters/hour WeightKilograms, Lbs. SpeedMiles or Km/hour AlphanumericASCII Characters AlphanumericKanji Characters Variable TypeUnits Switch StateBoolean Device StateBoolean EnergyKilowatt-Hours PowerWatts VoltageDC or AC RMS CurrentAmps AC, RMS ResistanceOhms Sound LeveldBrnc VoltagedB microvolts AlphanumericInternational characters Day of WeekEnumerated List (Mon-Sun) Elapsed TimeSecond, Milliseconds, Days or Hours Phone StateEnumerated List (On-hook, off-hook, busy, ringing, etc.) PressureLbs./sq.in, Pascals, Inches-Hg Relative HumidityPercent

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