4. What components of WACS are different from those of conventional BAS?

“This varies by vendor,” Osburn of Siemens said. “Ideally, the WACS solution uses the same ‘look and feel’ of the traditional BMS (building-management system) information. So training would be minimized and security would be the same. What is different can be the way in which connectivity is accomplished.”

“The device that connects (the control system) to the Internet may include a variety of functionality, from a limited message-routing service to a full-blown Web server and control engine,” Dennis Tuft, vice president of marketing for Tridium Inc., said.

Some vendors build servers into selected control modules, Tom of Automated Logic said, while some offer a software-based server that can be installed in any PC on a network.

“For a small, stand-alone system, the server and the browser can be installed in the same computer, so when the technician plugs his laptop into the control module, the laptop is acting as the server, creating the Web pages he sees on his browser,” Tom said.

More commonly, Tom continued, the control system will be connected to a computer network, with one of the computers acting as the server and making Web pages available to every other computer on the network. Larger systems may warrant a dedicated server: a PC with memory, disk capacity, and an operating system optimized for quickly providing Web pages to a large number of users simultaneously.

5. How are WACS integrated into a system design and ultimately specified?

“WACS can be integrated easily into the general system design by simply specifying that access shall be via a Web browser,” Haakenstad of Alerton Technologies said. “What may take some time is determining if the access is strictly via a LAN or a WAN or an ISP (Internet service provider) or ....”

“Often, this is a question to be answered by the corporate IT department where the system is installed,” Nations of Johnson Controls said. “Some departments have rigid rules that prevent connecting an internal system to the World Wide Web at all. Others are more flexible, yet still may have a rigid firewall that can be crossed only by an external device if it has the proper proxies on board. ...

“This raises the point about the relationship between the IT department and the facilities department,” Nations continued. “It varies from company to company. We’ve seen cases where the facilities department wants its own independent network because it’s worried about administrative and maintenance tasks performed by the IT department that could disrupt the operation of the physical plant. In other companies, the only option is to use a common backbone for all data systems.”

A wireless Web-accessible controls system can be integrated on the “equipment level,” providing an “avenue for additional functionality and savings,” Duffy of Notifact said.

When it comes to specification, the same rules that apply to conventional building-automation systems apply to WACS: Know what is available, decide what you want, and write it down, Tom of Automated Logic said.

“There are significant differences between the WACS offered by different vendors,” Tom said. “Look at what they have to offer and decide what features you need. Do you need the added security of Secure Socket Layer (SSL) communications? Which control functions do you need to access over the Web? Do you require use of an open protocol, such as BACnet, to provide interoperability with other vendors’ systems? Does your system need to support additional protocols, such as Modbus, SNMP, or LonTalk, in addition to its native protocol? Is your system large enough to require use of an enterprise-class database, such as Oracle or DB2? Is it desirable to have a platform-independent system that will run on Linux or Solaris as well as multiple flavors of Windows?”

Whether WACS are specified based on the level of system-interface functionality required, as Rae of Delta Controls suggested they be, or the same way that graphic-workstation capabilities are specified, as Osburn of Siemens recommended, the specification is driven by customer requirements, Ziejewski of Liebert said.

“The Web may not be cutting-edge technology,” Ziejewski said, “but since this is a well-known media, customers are demanding this type of interface.” Although the Web may no longer be cutting edge, it still is relatively new, and as with any new technology, writing specifications can be a challenge, Ehrlich of Trane said.

“Suppliers and consultants need to learn the new technology and create fair and impartial specifications,” Ehrlich said. “What typically is happening today with WACS is that the specifications are either vague or proprietary.”

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