Definitions

LonWorks

LonWorks

LonWorks is a networking platform specifically created to address the unique performance, reliability, installation, and maintenance needs of control applications. The platform is built on a protocol created by Echelon Corporation for networking devices over media such as twisted pair, powerlines, fiber optics, and RF. It is popular for the automation of various functions within buildings such as lighting and HVAC; see Intelligent building.

Origins and uptake

The platform has its origins with chip designs, power line and twisted pair signaling technology, routers, network management software, and other products from Echelon Corporation. In 1999 the communications protocol (then known as LonTalk) was submitted to ANSI and accepted as a standard for control networking (ANSI/CEA-709.1-B). Echelon's power line and twisted pair signaling technology was also submitted to ANSI for standardization and accepted. Since then, ANSI/CEA-709.1 has been accepted as the basis for IEEE 1473-L (in-train controls), AAR electro-pneumatic braking systems for freight trains, IFSF (European petrol station control), SEMI (semiconductor equipment manufacturing), and in 2005 as EN 14908 (European building automation standard). The protocol is also one of several data link/physical layers of the BACnet ASHRAE/ANSI standard for building automation.

China ratified the technology as a national controls standard, GB/Z 20177.1-2006 and as a building and intelligent community standard, GB/T 20299.4-2006; and in 2007 CECED, the European Committee of Domestic Equipment Manufacturers, adopted the protocol as part of its Household Appliances Control and Monitoring – Application Interworking Specification (AIS) standards

Usage

By 2006 approximately 60 million devices were installed with LonWorks technology. Manufacturers in a variety of industries including building, home, transportation, utility, and industrial automation have adopted the platform as the basis for their product and service offerings. Statistics as to the number of locations using the LonWorks technology are scarce, but it is known that products and applications built on top of the platform include such diverse functions as embedded machine control, municipal and highway street lighting, heating and air conditioning systems, intelligent electricity metering, subway train control, stadium lighting and speaker control, security systems, fire detection and suppression, and newborn location monitoring and alarming.

Technical details

Two physical layer signaling techologies, twisted pair "free topology" and power line carrier, are typically included in each of the standards created around the LonWorks technology. The two-wire layer operates at 78 kbit/s using differential Manchester encoding, while the power line achieves either 5.4 or 3.6 kbit/s, depending on frequency.

Additionally, the LonWorks platform uses an affiliated IP tunneling standard -- ANSI/CEA-852 -- in use by a number of manufacturers to connect the devices on previously deployed and new LonWorks -based networks to IP-aware applications or remote network-management tools. Most LonWorks -based control applications are being implemented with some sort of IP integration, either at the UI/application level or in the controls infrastructure. This is accomplished with web services or IP-routing products available on the market.

An Echelon designed 8-bit processor, the "Neuron chip", was initially the only way to implement a LonTalk node and is used in the large majority of LonWorks based hardware. Much later, the protocol was made available for general purpose processors: a port of the ANSI/CEA-709.1 standard to IP-based or 32-bit chips. However, this was a relatively recent development and has not been widely adopted.

Applications using LonWorks

SNVTs (Standard Network Variable Types)

One of the keys to the interoperability of the system is the standardisation of the variables used to describe physical things to LonWorks, this standards list is maintained by LonMark International and each standard is known as Standard Network Variable Types (SNVTs, pronounced "snivets") so for example a thermostat using the temperature SNVT is expected to produce a number between zero and 65535 that equates to a temperature between -274 and 6279.5 degrees Celsius.

External links

References

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