LonWorks FAQ
What is a control network and why are LonWorks networks smart networks?
A control network is a group of things (nodes or devices) that communicate with each other to implement an application that senses, monitors, or controls. Each device has one or more sensors or actuators, plus localized computational capability. The devices communicate over one or more media, using a standard protocol.
Control networks are more common than you think. For example, your car may have several control networks: in the seatbelt warning system, the ABS braking system, and the engine management system. A LonWorks based control network may have 2 nodes or 32,000, and can range in complexity from a simple alarm controlled by a remote occupancy sensor to a city's intelligent streetlighting system.
What makes a LonWorks based control network different from other control networks is the intelligence built into each LonWorks device. This lets each device respond to external events, act on network conditions, and conduct its own localized function — without needing a central controller. LonWorks devices also communicate directly with every other LonWorks device on the network. It is this set of attributes that make a LonWorks control network a smart network.
LonWorks control systems are used extensively in commercial buildings and factories to perform tasks such as sort books, build cars, and control elevators. The devices might communicate via peer-to-peer (distributed control) or master-slave (centralized control); in either case, intelligence in the devices (computational capability) lets them distribute processing loads. For example, intelligent sensors can perform local data analysis, conversion, and normalization, and report 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, 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 the name of our control networking technology platform and not just a protocol or physical layer for communications (such as Zigbee). The underlying communications platform, twisted pair signaling technology, power line signaling technology, and IP tunneling method constitute a global standard: ISO/IEC 14908.
LonWorks technology is called a platform because it's comprised of all the necessary elements to design, install, and manage control, sensing, and monitoring solutions:
- Communications protocol
- Dedicated microprocessor
- Transceivers
- Network database
- Internet connectivity
- Interoperability
Is the LonWorks platform a standard?
Yes. ISO and IEC have granted the underlying protocol of the LonWorks platform, power line signaling technology, twisted pair signaling technology, and IP compatibility status as a standard in the control and building management area. The ISO/IEC standards for the LonWorks platform are formally known as:
- ISO/IEC 14908-1. Communication protocol
- ISO/IEC 14908-2. Twisted pair wire signaling technology
- ISO/IEC 14908-3. Power line signaling technology
- ISO/IEC 14908-4. IP compatibility (tunneling) technology
The standard is commonly referred to as the ISO/IEC 14908-1 standards.
Numerous national and international standards bodies have also recognized the LonWorks platform by creating standards around it. These include:
- ANSI/IEC 709.1-B. Control networking and home control
- ANSI/ASHRAE 135-1995. MAC layer for the Building Automation and Control Networking standard
- IEEE 1473-L. Intra-car and inter-car communications for rail vehicle (passenger trains)
- AAR ECP. American Association of Railroads electronically controlled pneumatic braking systems
- EN14908-1. European Union intelligent buildings
- GB/Z 20177.1-2006. Standardization Administration of China control networking
- GB/T 20299.4-2006. Standardization Administration of China Digital Technique Application of Building and Residence Community
- SEMI E54.16. Semiconductor equipment manufacturers standard for sensor-actuator networks
What are LonWorks networks used for?
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
- Street lights
- Traffic lights
- Utility meter reading
- Vehicle wiring systems
- Vending machines
- Whole house automation
- Wire harness replacement
Who supplies the basic technology?
The principal suppliers of LonWorks networks are:
- Echelon Corporation. Development tools, smart transceivers, Neuron chips, network management tools, support and training.
- Cypress Semiconductor and Toshiba. Neuron chips.
- Authorized Network Integrators. Specification, design, and installation of LonWorks network solutions.
In addition, LonWorks developers worldwide supply everything from transceivers to network management tools to end-user systems.
Who uses it?
Companies that have adopted the LonWorks platform include:
- Most of the world's leading building automation system suppliers (such as Honeywell, Johnson Controls, TAC, and Distech Controls)
- Leaders in appliance, home, and building control (such as Samsung Electronics)
- Leading engineering firms (such as Teng and Associates)
- Transportation suppliers (such as Bombardier and Kawasaki)
In additional, many end user organizations require the LonWorks platform, including the US Army Corps of Engineers and the New York CIty Public Schools District.
What is a Neuron Chip and why use it?
The Neuron Chip is actually three 8-bit inline processors in one. Two are optimized for executing the protocol, leaving the third for the node's application. Thus, the Neuron Chip is both a network communications processor and an application processor. Up until recently, all devices on a LonWorks network required a Neuron Chip.
Why use it?
Having two processors dedicated to network tasks and one dedicated to application tasks ensures that the complexity of the application does not negatively affect network responsiveness and vice versa. Additionally, packaging both functions onto one chip saves design and production costs.
•Using 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.
As a result, 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?
Echelon's new Neuron 5000 Processor — a 40MHz implementation — paves the way for the highest-performing Neuron based LonWorks networks ever. (At one time the chip speed was limited to 10MHz.) The Neuron 5000 Processor marks Echelon's first entry into the standalone Neuron chip market.
As developers find more uses for the protocol, processing horsepower can become an issue, especially when there is more flexibility in costs. Since the protocol is a global and national standard in many markets, companies are free to port the protocol to any processor they choose.
How extensive is the communications protocol?
Protocols 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 (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 and recovery.
Is it reliable? What provisions for reliability are incorporated?
Reliable delivery is provided by using end-to-end acknowledgements made possible by using 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 and 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, and maintenance) facilities. All products can be installed at manufacturing time, and — unless prohibited by authentication — they can be designed for self-installation via third-party installation tools. Network management functions include node address assignment, multicast address group specification, router and bridge definition, network variable binding, communication service modification, network traffic data monitoring/collection, node/network diagnostics, and application code/data downloading.
If you use LNS, you can do many of these things simultaneously using devices and tools tailored for the operator/technician and the specific task.
Is it secure? Can access control 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 guarantees 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 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
- 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?
Interoperability means that products from multiple vendors can be integrated into flexible, functional systems — without the need for custom hardware, software, or tool development. Integrated products do more than just recognize each other; integration means that a single room occupancy sensor controls the HVAC, lighting, and security systems in a commercial building. It means that your assembly line reacts to your building's fire-detection system.
Benefits of Interoperability
- Interoperable products let project engineers 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 letting you compete for what would otherwise be closed bids.
- Interoperability decreases your own products' costs by letting your engineering teams build to a standard specification.
- Interoperable systems let building and plant managers monitor facilitywide use of standard tools, regardless of which company made a particular subsystem.
For users of control networks, interoperable products can their expand business, increase their profit margins, save their customers money, and offer them increased vendor choices when specifying systems. In short, interoperability is good for everyone.
To help lead the mission of delivering interoperable LonWorks based products to the control market, Echelon is a sponsor member of the LonMark Interoperability Association.
How do LonWorks networks ensure product interoperability?
We offer a three-part solution to the interoperability challenge:
- Until 1996, Echelon made the protocol available on the Neuron
Chip only. Since most every LonWorks node available today has a Neuron
Chip in it, they share a baseline level of interoperability. Encapsulating
as much as possible into standard silicon reduces the potential for
diverging interpretations, and serves two purposes:
- It gives every LonWorks application that uses Neuron Chips a fundamental commonality at the silicon level.
- And, it provides over 3 million devices installed worldwide, each which can be thought of as 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.
- It incorporates standard types and 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.
- An independent body, LonMark International manages the evolution of both the interoperability guidelines and the certification of products that conform to the interoperability standard. LonMark is also active in the international standard-setting process, helping bodies such as CECED, ISO/IEC, and CEM establish the LonWorks platform as a standard in their respective jurisdictions. LonMark International also trains and certifies system integrators, and educates end-user organizations about the benefits of interoperable LonWorks based systems using LonMark certified products and system architecture. There are more than 700 members in LonMark International and dozens of country-based LonMark Affiliate organizations.