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Web-based control: The next step toward interoperability
Building automation system (BAS) designs continue growing and evolving. Advances in low-cost, high-performance microcomputers and the widespread growth of high-speed, high-capacity communication lines and networks have driven the latest steps in this evolution. And today, the power and flexibility of the Internet is helping to take BAS capabilities to new levels.
Early-generation BAS were developed using proprietary communication protocols and data structures. Each system manufacturer developed its own standards, making it difficult or impossible for facility executives to modify or expand systems. Even different systems from the same manufacturer were frequently incompatible with each other, further limiting the options of managers. Proprietary systems proved to be difficult to learn, operate and manage. And as systems aged, facility executives frequently found that they owned orphaned systems no longer supported by their manufacturer.
Interoperability and the switch to open standards were intended to remove these and other barriers to the use of BAS. But while the development and use of standards, including BACnet and LonWorks, have moved the industry forward, they have not fully resolved the problem of system interoperability, particularly when BAS try to interface with enterprise-level IT systems.
The latest generation of BAS may finally be moving BAS to true enterprise-wide interoperability by incorporating Internet standards and communications protocol. By developing systems that adhere to these standards and protocols, new-generation systems are achieving interoperability at the hardware level, allowing users to access information using standard and widely applied Web browsers, such as Netscape and Internet Explorer.
Web-Based System Advantages
There are several approaches that vendors have taken to use Web technology. Most fall into two categories: Web-based and Web-enhanced. True Web-based systems are designed from the ground up as a Web application. Web-enhanced systems are those that achieve Internet compatibility by adding software products that convert and export information to the Web.
In enhanced systems, the software itself is not Internet compatible; only the data and information that has been passed through the conversion utility or gateway adheres to Internet standards. Although both approaches to BAS will work successfully, there are a number of advantages to the Web-based approach. The standards and protocols used to access the Web are well defined and mature, making it fairly simple to achieve fully interoperable systems. In contrast, the ease with which Web-enhanced applications can be interconnected depends to a great extent on how those applications were written. Web-based BAS also have the advantage of having all system software reside on a single Web server. All that is required for a user to log onto and use the system is a standard Web browser. Because no additional software must be purchased and installed on user machines, software licensing, setup and maintenance costs are reduced. Additionally, because all that is required at the user workstation is a Web browser, there are no limitations on what type of workstation can be used. Web-based BAS is ideal for use in applications having multiple sites. The Web provides the communications link between sites without requiring the use of dial-up access or dedicated phone lines. And with all software residing on a single server, IT staff involvement at remote sites is reduced.
The rapid growth of the building automation industry has given facility executives a number of options when selecting systems for use in their facilities. While there is no universally best-suited system, facility executives can begin to evaluate the suitability of particular systems by looking at a number of features found in those systems, including the following:
Web-based vs. Web-enhanced. While manufacturers may make confusing claims concerning their systems’ Web capabilities, there is one relatively simple measure that can be used to determine what type of system it is. If any software other than a Web browser is required to be installed on any user’s computer, then the system is Web-enhanced, not Web-based. Web-based systems offer greater flexibility and more widespread access, without requiring the purchase of licensed software for each user’s computer.
Open Protocol. With the demand for interoperable systems, manufacturers base their system designs on open standards and protocols, such as BACnet, LonWorks, and Modbus. Even with a Web-based system, the design must use one of the accepted standards. Compliance with Internet standards allows operators to access all BAS through a common interface, but it does not guarantee that different components in separate systems will be able to communicate effectively with each other. Making certain that the system architecture adheres to one of the interoperability standards is the only way to ensure true interoperability among building systems.
System Backup. While having all software reside on a single Web server simplifies the operation and maintenance of the BAS, it does carry its risks. What happens when the server crashes? Is there a backup server that automatically takes over system operation? What happens to the entire system if communications are disrupted? Just imagine the impact that a complete system failure would have on the operation of the facility. Will HVAC systems continue to operate? What about metering information necessary for billing or demand control? The system manufacturer should identify how their system handles these and other system problems.
Security. Any BAS that allows users to access system information or initiate control actions over the Internet can also be hacked by unauthorized outsiders. Not only can outsiders access confidential information, they can initiate control actions and other activities that — at best — would prove to be an inconvenience to building occupants and maintenance personnel. Some actions can result in costly damage to expensive building equipment.
To prevent unauthorized access to system information and building systems, the BAS must include several layers of security. Password protection schemes with multiple access levels should form the first level of protection. Then, limit system access to only those who are authorized. Transmissions that use 128-bit encryption on all communication between the Web browsers and the server reduce the possibility that a hacker can successfully tap into the system and capture passwords or sensitive data. Firewalls also can be very effective in keeping unauthorized users out of the system.
These and other security measures must be built into the system. Fortunately, any system that is Web-based can take advantage of many of the security schemes already in place for other applications, such as those used for on-line banking or secure data transmission. Make certain that the system under consideration has these capabilities built into it.
Data Storage Format. Many current systems use a proprietary method for storing information developed within the system. These proprietary storage methods make it difficult to share data across functions. As the Web-based systems are developed, there is a trend towards using standard data formats, such as XML. Systems that use a standard format make it easier to access, filter and sort large amounts of data. Standard data formats also make it possible to mix graphics and text. Hypertext links can be established between files, providing even greater and easier access to data. Information that is currently stored on paper also can be scanned into the system and incorporated into the overall BAS. By following existing standard formats, authorized users can access, revise and update any stored information.
Enterprise-level Applications. Don’t forget to consider the requirements for interfacing the BAS with enterprise-level applications. Making the BAS interoperable will provide great returns. But to achieve the highest level of returns, those systems must be able to exchange data with other systems in the facility. If those systems are not compatible, or will not be compatible for some time, the full return on the system investment will not be achieved. Temporary gateways might be needed to exchange data between the systems. Consider these requirements when evaluating system investments.
Building automation systems have come a long way in a short period of time. Protocol standards and the use of the Internet have greatly increased the interoperability of the systems, while improving functionality. The trend will continue. As the cost of microprocessors and other hardware continues to fall, look for the technology to be implemented at the device level. System controllers will be developed that have Internet communication protocol built in, making each device function like a Web server. A wide range of devices, such as temperature controllers and motor starters, will have an Internet protocol address built in. Connecting such devices to the Web will be greatly simplified, and real system interoperability will be achieved.
Contributing editor James Piper is a writer and consultant with more than 25 years of experience in the facilities field.