8. What are the computer-hardware and software requirements of WACS?

Web-accessible controls systems require two things, Rae of Delta Controls said: a server—“any Windows machine with the Web-server application installed”--and a client—“any device with Web-browsing capability.”

Tom of Automated Logic said his company recommends a 500-MHz Pentium III (or equivalent) minimum platform for central Web servers. For user workstations, he continued, the company recommends a 300-MHz Pentium (or equivalent) minimum platform with an Internet Explorer 5.5- or Netscape Navigator 6.0-compatible browser.

“Some of our customers prefer the Linux operating system or Sun Solaris computers,” Tom said. “... In many cases, the server simply is a rack-mounted network PC with no laptop, monitor, or other peripherals. Users access the server over the network and perform any required file updates, system backups, etc. remotely from their PC.”

Donlon and Kamal of Computrols said Web-server PCs require a minimum 300-MB hard drive; a Pentium 300-MHz processor; 64-MB RAM; a 10 Base T network card; and Windows 98, NT, or 2000 software.

Nations of Johnson Controls said buyers should avoid WACS technology that requires the operator to build custom Web pages for information to be served to remote users.

“Technology exists that allows the WACS portion of the system to automatically read the BAS database,” Nations said. “Whenever a change is made to the database, it automatically is available to those accessing the system via Web devices.”

9. Are WACS a retrofit solution, or are they feasible only for new systems? Can they be bootstrapped onto an existing BAS?

“Most WACS have some sort of gateway (hardware or software) that links multi-equipment communicating protocols from existing equipment,” Sophie Vandebroek, vice president of technology for Carrier Corp., said. “If so, there is a retrofit possibility.”

How great that possibility is depends on the system being retrofitted, Tom of Automated Logic said.

“If you are retrofitting a WACS made by the same vendor as the original system, and that vendor has built legacy support into the WACS, it may be a fairly simple retrofit,” Tom said. “If the vendor does not offer legacy support, or if the WACS is made by a different vendor, then there will be some custom engineering required, and the retrofit will be more difficult. Essentially, this becomes an interoperability issue. The retrofit obviously will be simpler if the existing system uses a standard protocol such as BACnet.”

If a system is more than a few years old, it most likely will need a software upgrade to allow the BAS to get data to the server, Nations of Johnson Controls said.

Duffy of Notifact said wireless WACS are designed for both new and retrofit systems.

“Some WACS can be hard-wired to points or sensors or receive signals from a BAS to send out alarm messages or receive setpoint commands,” Duffy said.

Although bootstrapping WACS features onto an existing BAS is possible, “In all likelihood, it will only provide limited Web visibility of selected parameters,” Tom said.

“Whenever possible, the goal should be to replace the existing BAS with a front-end that was designed from the ground up as a WACS,” Tom concluded.

10. What actually is “on the Web”? Do you need to register one or more domain names?

“A WACS is capable of being connected to the World Wide Web, and it uses Web standards to provide the user interface, but it does not have to be on the Web,” Tom of Automated Logic said. “WACS can be limited to a single office network or a company intranet, if desired.”

Ehrlich of Trane said most WACS are installed on intranets and rarely, if ever, are on the public Internet or World Wide Web. Nevertheless, when WACS are “on the Web,” what actually is there is the software that enables users to configure and distribute messages and record and maintain information, Duffy of Notifact said.

Nations of Johnson Controls said “high-end BAS functions” such as DDC- (direct digital control) sequence configuration and system-display design are seldom performed via WACS, that they normally are done on engineering workstations.

Regarding domain names, whether or not one or more are required for a WACS depends on the access scheme, Bredeson of Invensys said.

“If the access is only meant to be offered through an intranet or VPN (virtual private network), then no domain names are required,” Bredeson said. “However, if the product is hosted at a remote site, and Internet access is required, then at least one domain name is required. In this case, there would need to be at least one public IP address reserved as well.”

If an organization already has a Web presence, Tom said, a WACS can be established as a subdirectory, or “cname,” of the organization’s existing domain.

“For example, www.wacs.xyzcompany.com could provide WACS access through the existing xyzcompany.com domain name,” Tom said.

Next month: answers to questions 11-20. Read 20 Questions About WACS Answered: Part 2 here.

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