Seeking lower costs and improved functionality, suppliers of control systems are embracing open, interoperable systems that integrate multi-vendor HVAC, lighting, life/fire/safety, security and other controls. Just as the PC caused an explosion in the use of computing technology by lowering costs and providing flexibility, the use of standard, interoperable control technology lowers the installed cost of control systems, and introduces efficiencies and savings throughout system life cycles.

Successful integration of products from different vendors requires the adoption of a unified communications technology. By having common communications, costly custom hardware, software or other gateway options are eliminated. Open “peer-to-peer” (distributed control) communication technology supports a new generation of products and systems which are less costly to operate. It also provides unprecedented freedom to change or modify systems in the future, resulting in improved subsystem integration, reduced life cycle costs, and comfortable, safe environments.

For many control system suppliers, LonWorks® control network technology, introduced in 1991, by Echelon Corporation, a Palo Alto, California-based company, makes the goals of distributed control a reality. In a LonWorks network, intelligent control devices, called nodes, communicate with each other using a common protocol. Each node contains embedded intelligence that implements the protocol to monitor and/or control functions. There may be 3 or 30,000 or more nodes in a network: sensors (temperature, pressure, passive infrared, etc.), actuators (switches, ballast controllers, circuit breakers, pool pumps, etc.), operator interfaces (displays, touch-screen terminals, man-machine interfaces, etc.), and controllers (room controllers, set-top boxes, utility gateways, etc.). By eliminating the need for the central controller, PLC or computer — often the Achilles’ heel of conventional control system hierarchies — distributed control has been shown to enhance system reliability, responsiveness and predictability, while lowering installation and life-cycle costs.

Communication tasks are managed through a powerful integrated circuit (IC) that allows devices to make decisions and communicate those decisions to other intelligent devices in the network through one or more communications media. The media can consist of twisted pair wire, power lines, coaxial cable, optical fiber or wireless methods like radio frequency and infrared. The flexibility to support one or more media makes LonWorks networks an attractive solution for retrofits where existing twisted pair, structured cabling or power lines may be used.

To a degree, LonWorks nodes on a LonWorks network are analogous to personal computers on a data network. However, unlike data networks, which are optimized for large file transfers on high bandwidth media, control networks send small control messages originating with sensors, that contain “state information” instead of large files of data. Actuators on the network observe this state information and make a local decision on what kind of action to take with the damper, valve or other device to maintain control of the system. Devices in the network are installed in the field using off-the-shelf network management software running on Windows 95, Windows NT, or other platforms. Once devices are installed, the network manager can either remain connected to the network or can be disconnected. Since the intelligence is distributed in the field devices, no supervisory controller is required for the system to operate.

The Network Advantage

The advantages of a highly distributed, flat architecture peer-to-peer system over a traditional hierarchical system are:

· Most, if not all, field panels are eliminated from the design. This reduces hardware costs and eliminates the most frequently cited liabilities to a field panel design: expansion capacity and reprogramming required for simple changes.

· The need for home run wiring is eliminated in the network design, saving pipe, wire and associated labor costs.

· Replacing copper and the associated labor costs with silicon and software means that future devices can be added to the system at lower costs, which means the whole system costs less over time.

· Adjustments and additions to the system are achieved “logically” by changing assignments (bindings) of messages using software tools. This eliminates the need to rewire the system to accommodate future modifications.

The LonMark Interoperability Association

The trend toward open, interoperable systems is evidenced by the number of companies embedding LonWorks control network technology in their products and following the interoperability guidelines established by the LonMark® Interoperability Association.

Founded in August 1994 by 36 companies to facilitate the development and implementation of open interoperable LonWorks-based control products and systems, the LonMark Interoperability Association has grown to over 200 members today. The members include end-users, integrators and manufacturers including virtually every major controls company in the building industry worldwide. The Association provides an open forum for member companies to work together on marketing and technical programs to advance the LonMark standard for open interoperable controls. Its three major functions are:

· Definition of design guidelines for interoperable devices based on LonWorks technology.

· Certification of products that meet the LonMark standard for interoperability.

· Promotion of LonMark products and systems as open, interoperable control solutions.

The Association develops technical design guidelines for products to ensure that they can be easily integrated into multi-vendor LonWorks networks using standard tools and components. These guidelines require the use of standard data objects and types and self-documentation to support easy installation and configuration of systems using third-party tools.

The availability of LonMark products is providing end-users, network integrators and equipment specifiers the benefits of open, interoperable, multi-vendor systems:

· Choice of vendors

· Use of third-party tools

· Easier integration

· Reduced installation costs

· Easier additions and changes

This frees end-users from lengthy, costly service and upgrade agreements with a single vendor. Now end-users can implement control systems using LonMark devices from multiple vendors, confident that whatever they choose can be easily integrated.

The Electronic Industries Association’s (EIA) Integrated Home Systems (IHS) technical committee, created to look at alternative standards for home networking, formed a sub-committee on August 29, 1996 to consider an additional EIA standard for home networking based on Echelon’s LonWorks network technology. The committee, IHS-1, is completing the new specification, EIA 709 version expects to begin ANSI balloting in 1998.

All Roads Lead To Interoperability

Delivering truly interoperable solutions has been a standing goal for Echelon and members of the LonMark Interoperability Association. While the number of LonMark approved devices available in the market today is rapidly increasing, there are still gaps in the range of products needed to build complete solutions. This is especially true in retrofit applications where it is necessary to integrate legacy sensors and actuators into a control network that include LonMark devices. Further complications emerge in finding adequate network installation tools and qualified integrators to deliver true, integrated solutions.

Recognizing the problems facing the industry, Echelon stepped in to deliver the missing pieces through the creation of the LonPointTM System and the Network Integrator Channel. The LonPoint System is a collection of intelligent control devices and network software that provides the infrastructure needed to build open, interoperable, multi-vendor, control systems.

The LonPoint System includes a family of interface modules that provide various combinations of digital or analog inputs and outputs along with numerous software function blocks, allowing seamless connectivity to legacy field devices and to LonMark devices.

Echelon is also introducing the LonMakerÃ’ for Windows network management tool for installing, monitoring and configuring a LonWorks network. Unlike the previous version of the LonMaker installation tool, this version incorporates Visio’s user-friendly graphical interface, the LNS network operating system, and object oriented software plug-ins to greatly simplifying network installation.

Network Integrators Deliver Solutions Today

With over 1,500 shipping products and more than 3,500 control system suppliers in development of product, there is a large and growing need for qualified integrators. In order to help the building industry respond to the growing demand for interoperable solutions, Echelon is introducing the Network Integrator Program. This program provides the necessary products, tools and training required to help network integrators install, commission and maintain LonWorks interoperable solutions.

Implementing completely distributed, interoperable control networks is possible today, thanks to Echelon and the many suppliers of LonMark certified products. The growing availability of products displaying the LonMark logo is making it easier for specifiers, integrators to create lower cost, more flexible, and more efficient automated solutions today.