A control network is a group of things (nodes - each with one or more sensors or actuators, plus localized computational capability), that communicate (over one or more media, using a standard protocol) to implement a sense and control, sense, or monitoring application.
Control networks are more common than you think. For example, your car may have several control networks in, e.g., the seat belt warning system, the ABS braking system or the engine management system. A control network may have 3 nodes, or 300, or 30,000, or more and can range in complexity from a few “smart” light switches on a timer to a jet passenger airplane (both of which are examples of existing LonWorks networks). It may be a simple alarm controlled by a remote occupancy sensor, or a city's traffic management system, monitoring and controlling signal lights, traffic flow, the actions of emergency vehicles, power distribution, etc.
To many people, control networks are most easily understood as smart houses or home automation. However, most control systems in use today are in commercial buildings and factories doing such things as sorting books or building cars or controlling an elevator. LonWorks networks are used for all of these and more. Communication among the nodes may be peer-to-peer (distributed control) or master-slave (centralized control); in either case, intelligence in the nodes (computational capability) permits the distribution of processing loads (sensors can be intelligent, for example, performing local data analysis, conversion, & normalization, and reporting only significant changes in their environment). If the control functions are also distributed, both system performance and reliability can be dramatically enhanced.
As Robert Metcalfe, the founder of 3Com Corporation, once said, "The power of a network is proportional to the number of nodes on it." Given that there are vastly more nodes performing control than data functions (LANs), it's clear that the most powerful networks in existence are control networks.
What is the LonWorks Platform?
LonWorks is a networking platform created by Echelon. LonWorks networks really describe a complete solution to the problem of control systems. Like the computer industry, the control industry was, and in many cases is, creating centralized control solutions based on point-to-point wiring and hierarchical logic systems. This meant that you had a “master” controller, like a computer or programmable logic controller, physically wired to individual control, monitoring and sensing points, or “slaves.” The net result worked, but was expensive and difficult to maintain, expand, and service. It was also very expensive to install.
LonWorks networks started out with some very simple notions - control systems are fundamentally the same regardless of application; a networked control system is significantly more powerful, flexible, and scaleable than a non-networked control system; and businesses can save and make more money building control networks over the long term than they can with non-networked control systems.
LonWorks technology provides a solution to the many problems of designing, building, installing, and maintaining control networks: networks that can range in size from two to 32,000 devices and can be used in everything from supermarkets to petroleum plants, from aircraft to railway cars, from fusion lasers to slot machines, from single family homes to skyscrapers. In almost every industry today, there is a trend away from proprietary control schemes and centralized systems. Manufacturers are using open, off-the-shelf chips, operating systems, and parts to build products that feature improved reliability, flexibility, system cost, and performance. LonWorks technology is accelerating the trend away from proprietary control schemes and centralized systems by providing interoperability, robust technology, faster development, and scale economies.
Echelon manufacturers over 80 products to help developers, system integrators, and end-users implement LonWorks networks. These products provide a complete LonWorks solution including development tools, network management software, power line and twisted pair transceivers and control modules, network interfaces, technical support and training.
What are LonWorks Networks used for?
In theory, all control network applications, across all industries.
Applications for which LonWorks networks technology are used today include appliance control, asset tracking, automated supermarket pricing, automated work environments, avionics instrument integration, circuit board diagnostics, consumer electronic controls, discrete and process control, electronic locks, elevator control, energy management, environmental monitoring, fire protection, HVAC control, highway toll collection, identification systems, intelligent industrial I/O, irrigation management, lighting control, liquor dispensing, livestock management, medical instrumentation, office machine automation, patient monitoring, power supply management, research experiment monitoring, restaurant automation, security systems, slot machines, traffic lights, utility meter reading, vehicle wiring systems, vending machines, whole house automation, wire harness replacement, and many more...
Echelon Corporation - the LonPoint System, development tools, transceivers, network management tools, support and training (creator of the technology, and provider of transceivers, connectivity products, development tools, and training)
Cypress Semiconductor (beginning year 2000) and Toshiba - Neuron chips (competing world-wide suppliers of variously packaged versions of the Neuron chip)
Additionally there are over 4000 LonWorks developers world-wide supplying everything from transceivers to network management tools, to interfaces, to end-user products and systems.
Who uses it?
Over 4000 companies use LonWorks networks today, and their numbers are growing rapidly. These include Companies that have made public statements about their usage include ABB Network Partner, ABB-Stromberg Power, Acromag, Action Instruments, Advance Transformer, AEG, Ahlstrom Elari, Allen-Bradley, American Sports Timing, AMP, AT&T, Bally Systems, Barrington Systems, Bell Northern Research, BTE, British Petroleum, British Telecom, Brooks Instrument, Card Monroe, Carrier Corp., Controlli S.P.A., Danfoss Automatic Controls, Detroit Edison, EG&G Idaho, EIL Instruments, Fabrisys (Alcatel Cable), Ferag AG, Goldstar Industrial Systems, Helvar, Hewlett-Packard, Honeywell, Hubbell, ITT Barton, Jet Propulsion Laboratory, Johnson Controls, Keene Widelite, Kollmorgen, Legrand, Lakewood Instruments, Landis & Gyr Powers, Leax, Legrand, Leviton Manufacturing, Lithonia Lighting, Litton Poly-Scientific, McQuay International, Metra Corporation, MK Electric, Molex, Montgomery Elevator, NASA, Nippon Steel, Olivetti, Orr Safety, Pensar Corporation, Philips Lighting, Potter Electric Signal, Raychem, Scitronix Corporation, Shlumberger Industries, Sea Hornet Marine, Sentrol, Siebe Environmental Controls, Solus Technology, Square D, Staefa Control Systems, TAC GmbH Control Systems, Toshiba Lighting, Trans-Lite, Trend Control Systems, Tru-Measur, Unisys, Weidmuller, Woodward Governor, and many more...
Shouldn't I wait for a standard?
Yes and no. Standards are very important and often necessary. However, the true strength of a technology is in its acceptance and use as a de facto standard, not in its pedigree. The LonWorks platform is a part of several standards and is a de facto standard in many segments of the controls market. Manufacturers, end-users, integrators, and suppliers are seeing increasing demand for control solutions that have the capabilities that LonWorks networks deliver. As a result, millions of devices have been installed worldwide in thousands of LonWorks solutions.
LonWorks networks have been included in several standards or standards efforts including:
The protocol has been included in EIA-709.1, the Electronic Industries Alliance (EIA) Control Network Protocol Specification. It is available for purchase from Global Engineering Documents.
The protocol is part of the American Society of Heating, Refrigeration, and Air-Conditioning Engineers' BACnet control standard for buildings. This is now known as ANSI/ASHRAE 135.
LonWorks is also the standard protocol of the International Federation of Forecourt Standards (all European gasoline stations).
The American Association of Railroads has chosen LonWorks as the standard for pneumatic braking systems.
SEMI (Semiconductor Equipment Materials International) specifies LonWorks as a sensor bus for connecting simple as well as complex sensors, actuators and instrumentation within equipment and between equipment in E-56.6.
What is a Neuron?
The Neuron is actually 3 8-bit inline processors in one. Two are optimized for executing the protocol, leaving the third for the node's application. It is therefore both a network communications processor and an application processor. Up until recently, all devices on a LonWorks network required a Neuron.
Why use a Neuron?
Having two processors dedicated to network tasks and one dedicated to application tasks ensures that the complexity of the application does not negatively impact network responsiveness and vice versa. Additionally, packaging both functions onto one chip save design and production costs.
Use of the Neuron chip guarantees a controlled hardware execution environment for the protocol. To ensure sufficient processing power, the protocol is implemented with a mixture of hardware and firmware.
The creation of a custom chip also allows the inclusion of additional functionality to facilitate control node design. The Neuron chip, for example, incorporates watchdog timers, on-board diagnostics, 35 device controller types, a distributed real-time operating system, run-time libraries, three types of memory, and even a 48-bit software-accessible serial number (which, guaranteed by the chip's manufacturers to be unique, provides an always-available installation address for any Neuron chip-based node).
Designed for a broad range of industries and applications, and consequently manufactured in volume by two of the world's largest semiconductor manufacturers, the Neuron chip offers a lower-cost instantiation of the LonTalk protocol than could be achieved in custom implementations.
The net result is that the Neuron Chip is the best and most economical LonWorks processor for anyone requiring 8-bit processing power.
How fast can the protocol be run?
At one time the speed was limited to 10MHz. However, a new 20MHz implementation has been completed opening the way for the highest performance Neuron based LonWorks networks ever.
Further, as the developers find more uses for the protocol, processing horsepower can become an issue. Echelon has addressed this by opening up the LonTalk protocol to allow any company to port it to the processor of their choice. This means that applications requiring 16 or 32 bit processing power, can now host the protocol in native mode.
How extensive is the communications protocol?
Protocols today are generally designed to follow the ISO standard "Open Systems Interconnection Reference Model," which encompasses a full set of protocol features, and classifies them according to seven functional categories (referred to as "layers"). Thus the "seven layer OSI model".
The LonTalk protocol implements all seven layers of the OSI model, and does so using a mixture of hardware and firmware on a silicon chip, thus precluding any possibility of accidental (or intentional!) modification. Features include media access, transaction acknowledgement, and peer-to-peer communication, and more advanced services such as sender authentication, priority transmissions, duplicate message detection, collision avoidance, automatic retries, mixed data rates, client-server support, foreign frame transmission, data type standardization and identification, unicast/multicast/broadcast addressing, mixed media support, and error detection & recovery. For an overview of the LonTalk design, and the benefits of fully functional protocols, refer to "LonTalk Protocol Rationale", available from Echelon Corporation.
Is It Reliable? What provisions for reliability are incorporated?
Reliable delivery is provided by using end-to-end acknowledgements made possible by the use of a seven layer OSI stack, 16-bit cyclical redundancy checks, watchdog timers, and, in the case of certain transceivers, the use of error correction algorithms.
Is performance predictable?
An integral part of the protocol used in LonWorks networks is its unique media access technique, termed "predictive persistent CSMA, with optional priority & collision detection." It provides linear response to offered traffic load, predictable response time for heavily loaded networks, and consistent performance independent of network size.
What about network management?
LonWorks networks incorporate a full set of network management (installation, configuration, & maintenance) facilities. All products can be installed at manufacturing time, and - unless prohibited by authentication - by using third-party installation tools; they can also be designed for self installation. Network management functions include node address assignment, multicast address group specification, router & bridge definition, network variable binding, communication service modification, network traffic data monitoring/collection, node/network diagnostics, application code/data downloading, etc.
If you use LNS, then you get the added benefit of being able to do many of these things simultaneously using devices and tools tailored for the operator or technician and the specific task.
Is it secure? Can access control (security) be guaranteed?
All network operations (including network management) are performed using a full "sender authentication" as a Layer 4 (of the OSI model) service (this provides a guarantee of sender authenticity, which cannot be forged or "hacked"). Every packet transmission can use sender authentication. The bottom line is that you can invoke this facility. Thus, by a selective use of authentication, security firewalls can be established where appropriate. And because the protocol is embedded in silicon, authentication is guaranteed to work throughout the network, regardless of individual product implementation choices.
What does the programming model look like?
Applications for LonWorks networks are written in “Neuron C.” This is really just ANSI C, plus three extensions:
A new statement type, the "when" statement, to introduce "events", and define task execution order;
37 additional data types, 35 I/O objects and 2 timer objects, to simplify and standardize device controller usage, and;
Integral message-passing mechanisms for both explicit (physical, logical, and destination-name addressing) and implicit (network variable) message formats.
Neuron C uses a programming model based on events. In other words, applications are typically triggered by events occurring elsewhere on the network or at the particular node. Therefore, the network itself is event driven. This means that LonWorks networks have much lower traffic than other types of networks, like your office LAN.
What is interoperability and what are its benefits?
Echelon defines interoperable as the ability to integrate products from multiple vendors into flexible, functional systems without the need to develop custom hardware, software, or tools. By integrate, we don't just mean see each other, we mean being able to do things like use only one room occupancy sensor for the HVAC, lighting, and security systems in a commercial building. We mean being able to have your assembly line react to your building's fire system.
To help lead in the mission of delivering interoperable LonWorks based products to the control market, Echelon is a sponsor member of the LonMark Interoperability Association.
Four Benefits of Interoperability
Interoperable products allow project engineers to specify best of breed systems rather than be forced into using one vendor's entire line of products.
Interoperable products increase the overall market for your products by allowing you to compete for what would otherwise be closed bids.
Interoperability decreases your own products costs among your business' division by allowing your engineering teams to build to a standard specification.
Interoperable systems allow building and plant managers to monitor facility wide using standard tools, regardless of which company made a particular sub-system.
How is product interoperability assured?
For many users of control networks, this is the single most important question. Interoperable products can expand your business, increase your profit margins, save your customers money, and offer you increased vendor choices when specifying systems. In short, it's good for everyone from developers, to integrators to end-users. Integration without frustration - the ability to integrate products from multiple sources without the need for custom development - can be the driving force that leads to the search for a control network technology.
LonWorks networks approach interoperability in three main ways. Technology offers a three-part solution to this challenge.
First, up until 1996, Echelon made the protocol available on the Neuron Chip only. Since most every LonWorks node available today has a Neuron in it, they share a baseline level of interoperability. It encapsulates as much as possible into standard silicon, to reduce the potential for diverging interpretations. This serves two purposes. One, it provides to every LonWorks application utilizing Neurons a fundamental commonality at the silicon level. Two, it provides over 3 million (and counting) devices installed world-wide, and each can be thought of a an interoperability reference for any ported processor (non-Neuron processors running the LonTalk protocol). Echelon ensures, via license, that any port of the protocol must interoperate with the Neuron chip.
Second, it incorporates standard types & objects (so products can agree on the meaning of shared data), and an intrinsic control model (because extrinsic control limits interoperability) into the programming model.
Third, an independent body, the LonMark Interoperability Association, has been established to manage the evolution of both the interoperability model and the certification of products that conform to the interoperability standard.
There are presently over 300 members from more than 25 countries, including Cypress Semiconductor, Echelon, Enel.it S.p.A., Fuji Electric Co., Honeywell, Johnson Controls, Philips Lighting, Schindler Elevator Corp., Siemens Building Technologies, STMicroelectronics, TAC, Toshiba and Trane.
The association establishes technical guidelines and promotes the LonMark interoperability standard worldwide.
