Think this "ideal" open system sounds like a pipe dream? Take a look around at the ASHRAE trade show in February. You just might find a system that surprises you.

Web Technology Revolutionizes the Concept of Open Systems

The idea of open systems has become so popular that nearly every manufacturer claims to offer one, and the corporate "spin doctors" are twirling to new heights in their attempts to create definitions of open systems which include their products. Much attention has been focused on communication protocols, with BACnet supporters battling the LonWorks camp for the title of "most open." In reality, communication protocols are only one part of a building automation system, and a truly open system must be open at all levels. This means it needs to use an open communications protocol, be accessible from any computer on the network, be written in a platform-independent language, use an industry standard database, and provide the user with all necessary programming tools. That's a pretty tall order, but fortunately technology is available to make this possible.

The World Wide Web is the largest open system in history, and the technology that makes it possible to access sites from Arkansas to Zanzibar can make your building's data available to authorized users anywhere in the world. The word "authorized" is important, and the security encryption that protects your credit card transactions on the web can protect your facility data. Web technology includes more than just transmitting data across the web, it also involves providing data in the form of web pages. This allows any computer with a web browser to view and edit the data, not just a computer loaded with the control vendor's software. This is especially important to customers who have many technicians supporting a wide network of controls, such as a typical college campus. Purchasing building automation software for multiple computers can be expensive, and it ties the technicians to those computers. With web technology, technicians can monitor, troubleshoot, and repair the system from any computer on the network. If that network happens to be the Internet, technicians can work from virtually any computer in the world. For maximum flexibility, the web pages themselves should be based on open standards like HTML and JavaScript. This allows the data to be accessed by computers running Windows, Unix, Linux, Apple OS, or other operating systems commonly found on large systems.

In addition to "platform independent" web pages, the software that generates these pages should be written in Java so the web server itself can run on any operating system. The server should also use an industry standard database that supports CORBA (Common Object Request Broker Architecture) to store vital system data so the data will be available to many different software applications. Configuring the system and programming the controllers requires special programming tools, so the control system vendor should provide the customer with all tools and documentation required to allow the customer to modify or expand their building automation system. With these, the customer is not "locked in" to a single vendor when changes are needed.

Finally, an open system must use an open communications protocol. Since the corporate spin doctors can't agree on what constitutes an open protocol, let's use a neutral definition, provided by a recognized authority on the telecommunications revolution. MIT Professor Nicholas Negroponte says "A truly open system is in the public domain and thoroughly available as a foundation on which everybody can build." BACnet, which was developed by ASHRAE, has been adopted by ANSI, and is being reviewed by ISO for adoption as an international standard, fits this definition to a "T." It's important this protocol be the "native" language used throughout the control system. Gateways, or custom-programmed "translators" which provide an open protocol at one or two points are better than nothing, but the end result is the vendor who controls the gateway controls the system.

Think this "ideal" open system sounds like a pipe dream? Take a look around at the ASHRAE trade show in February. You just might find a system that surprises you.

About the Author

Steve Tom, PE, PhD, is the Director of Technical Information at Automated Logic Corporation, Kennesaw Georgia. He coordinates the Training, Documentation, and Technical Support programs at ALC, and works with their R&D engineers to improve the usability of new products.

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