Windows Terminal Services technology may not be revolutionizing LITESPEC Optical Fiber's approach plant-floor supervisory control, but it certainly improves the reliability of that approach, and cuts costs in the process. That's an evolution that David Criswell, a senior systems engineer and information systems support supervisor for LITESPEC, is happy about.
Windows Terminal Services technology may not be revolutionizing LITESPEC Optical Fiber’s approach plant-floor supervisory control, but it certainly improves the reliability of that approach, and cuts costs in the process. That’s an evolution that David Criswell, a senior systems engineer and information systems support supervisor for LITESPEC, is happy about.
"Now that I see how Terminal Services thin clients work, I’m very pleased," say Criswell. "I can’t imagine putting PCs out on the shop floor again; we’ll be using thin clients instead."
LITESPEC is a Research Triangle Park, N.C.-based single-mode optical fiber manufacturer. It’s among the manufacturing enterprises using Terminal Services—a technology that delivers Windows-based user interfaces to diverse computer hardware via a form of terminal emulation—to provide thin-client access to supervisory control applications.
The Terminal Services architecture runs applications on the server while delivering the Windows 2000 experience to desktops or remote computing devices—including those running operating systems other than Windows 2000, such as Windows CE, Embedded Windows NT, Linux, UNIX, and Macintosh. Operators log on at a thin-client terminal and receive only the presentation, called a session, managed transparently by the server independently of other client sessions. Only screen, mouse, and keyboard information is transmitted over the network between the client and the server.
Terminal Services capabilities are part of Redmond, Wash.-based Microsoft Corp.’s Windows 2000 operating system offering, but vendors of supervisory control software also have developed Terminal Services editions of their packages to fully exploit the technology. Other plant automation players have added high-availability solutions for Terminal Services environments.
While other thin-client technologies, such as Java and HTML, grab much of the attention of information technology (IT) analysts, at the plant level, Terminal Services quietly continues to be adopted. It promises lower total cost of ownership (TCO) via hardware savings, centralized software management, and remote communications capabilities.
Remote access
One reason for manufacturers’ growing interest in Microsoft Terminal Services is the amount of flexibility thin clients offer, says Janie West, product manager for visualization products at Wonderware, an Lake Forest, Calif.-based industrial automation software supplier. "Users are able to deploy all thin clients, mix fat and thin clients, offer thin-client view-only access for casual users, and even offer remote access," West says.
If an operator is off-site and an operator problem occurs, they’re able to dial in via a remote access server and request simultaneous control of the session, West says. Terminal Services also supports wireless remote devices as thin clients for mobile access using Terminal Services Advanced Client to gain Internet connectivity.
"The result is that Terminal Services accommodates many types of scenarios, even remote access via a Web interface to monitor oil pipelines," West says. "Depending on the application and location of controls, dial-in remote access could offer tremendous return-on-investment."
It’s important to stress, however, that remote dial-in or Internet access do not relegate users strictly to view-only access, says Tim Donaldson, a technical marketing manager with industrial automation software supplier Intellution, Foxborough, Mass. "Via the Internet, it’s possible for a user with a Terminal Services thin client to do anything an operator at a traditional fat-client workstation does," he says.
Users are able to access Intellution’s iFIX human-machine interface (HMI) and control application, for example, with iClientTS, a Terminal Services-enhanced version of the company’s iClient client/ server application. Thin clients connect to the Terminal Server PC to access all the functionality available when working directly off the server. "That includes access to iFIX script, trend, alarm, and security features," Donaldson says. "Terminal Services thin clients are one more way for manufacturers to truly leverage the Internet and gain rapid returns while also substantially reducing total cost of ownership."
Gain flexibility
Considering that Microsoft technology is the de facto standard for human-machine interface (HMI) and supervisory control solutions, it comes as no surprise that vendors in this space—including Wonderware, USDATA, Rockwell Automation, and Intellution—all offer Terminal Services support.
Microsoft’s Terminal Services offering includes Terminal Server, the server component that supports multi-user sessions; a remote display protocol that enables clients to communicate with the server over the network; Terminal Server client, the client software to display the Windows user interface; and administration tools.
Terminal Server sessions consume minimal bandwidth. Rather than constantly changing screen content, only data that has changed is sent to the terminal, which significantly reduces network traffic.
Client terminals’ low installation cost is one factor that contributes toward manufacturers’ interest in the technology. According to research from Wonderware, deploying a 25-node supervisory control system under Terminal Services on new thin, diskless workstations would cost roughly $40,000. Deploying a 25-node system in a full client/server mode would cost an estimated $68,000.
Using older existing PC hardware with Terminal Services, rather than new thin workstations, would reduce costs even lower than $40,000. "By using the thin-client version of our InTouch HMI software, industrial automation users are able to realize tremendous savings in initial system costs," says Wonderware’s West.
Manufacturers have quite a bit of flexibility with thin-client configurations, West adds. For example, InTouch users are able to run tasks locally, or as a Terminal Services session. A user running an InTouch application may redeploy the application in Terminal Services, and extend use to multiple workstations. Users also may have one application on the server and execute it multiple times, in multiple sessions. Conversely, West says, users may have up to four different applications executing simultaneously on the server.
"Thin-client technology gives manufacturers a number of interesting options and benefits," West says. "As a result of a low installation cost, the ability to shift existing InTouch applications to Terminal Services architecture without a complete overhaul, and the ability to mix traditional fat with thin clients, Terminal Services for InTouch has been the fastest-adopted industrial technology Wonderware has ever offered."
LITESPEC is one of those users. It adopted Terminal Services after it purchased a new piece of prooftester equipment. The company uses the equipment to divide large spools of optical fiber into smaller spools—either to remove defects or to produce customer-specified lengths. Each prooftester includes a PC-based HMI for operator control, process monitoring, and data collection. It was quickly determined that the prooftester’s rudimentary HMI was insufficient and required rework, Criswell says.
Obvious opportunity
"The plant floor is extensively automated, and many of our HMIs incorporate Wonderware’s InTouch software," Criswell says. "When we decided to rework the new HMI, it was an obvious opportunity to investigate using Terminal Services thin-client technology with the InTouch application."
In conjunction with lower TCO, Criswell says LITESPEC sought improved system reliability. To meet that need, the company settled upon a Terminal Services system that leverages core Microsoft functionality, Wonderware’s Terminal Services for InTouch solution, and industrial thin-client technology from Automation Control Products (ACP), Alpharetta, Ga., including ACP’s ThinManager software for managing thin clients and providing failover features to ensure high system uptime.
"The plant floor is a tough environment for PCs, so they require a lot of babysitting. Between the unplanned and planned downtime, PCs on the plant floor are down frequently," Criswell says. "Even only running one server, one server for instant fail-over backup, and one thin-client node, we’ve noticed a dramatic improvement in ease-of-maintenance over PC performance. If the server requires planned downtime for an upgrade, we’re able to switch the thin client to the back-up server, and then switch back without losing factory control. That’s vital for LITESPEC because the facility is always running and we can’t afford to lose operator control, process management, or data collection functions."
Use of Terminal Services thin clients on the plant floor has worked out so well at LITESPEC that Criswell doubts the company will install any new PCs on the plant floor, and likely will replace existing HMI on old prooftesters with thin clients. "We also may consider thin client-based approaches to front-office desktop computing," Criswell says. "It would enable turning existing Windows-based PCs into thin clients to simplify administration, plus we could then extend the life of the hardware."
High availability
Manufacturers are quickly and widely adopting Terminal Services technology, in part, because thin clients offer a high level of availability, says Daryl Walther, RSView32 HMI product marketing manager at Rockwell Automation, Milwaukee. "It simply offers a robust architecture with better availability than is possible using client/server because the server for HMI and supervisory control applications is in a safe location, while the terminal remains on the plant floor where operators need it," he says.
"It can take a day’s worth of work to replace a PC on the shop floor if the hard disk was corrupted, and even after the PC is running again, information about the manufacturing process is lost," Walther adds. "In a worst-case scenario, production may even have stopped because a PC used for control was down. Thin-client terminals don’t have a hard drive that can crash, which greatly improves availability. Secondly, PCs in a hostile environment, such as a plant floor, tend to take a lot of abuse. Even if a thin-client terminal gets knocked over or is damaged in some way, it’s easy to swap terminals quickly and make a replacement. An additional benefit is that even if terminals must be switched, there is no resulting data loss. The I/O for a machine goes to the server, and that’s where the file resides as well."
Server-centric thin client strategies also enable higher levels of availability than those associated with client/server architectures. Although there are several methods of deploying system redundancy, load balancing and shadowing are the most favored, says David Hancock, an ACP vice president. For example, he says, three servers could each have 10 thin clients. In the event one server fails—or is purposefully taken down—half of its clients go to one server and the other five thin clients are picked up by the third server.
"The ability to easily configure a redundant server with fail-over capabilities is critical for manufacturers because it doesn’t require creating difficult-to-maintain custom coding or scripting. The Terminal Services thin-client architecture enables running a server with a backup running in hot standby so it receives data from the master server and constantly stays in-sync," says Mitch Vaughn, chief technology officer at USDATA, Richardson, Texas. "If the master server has a problem—or if the manufacturer plans to take it down—the other server takes over and functions as the master. The benefit for manufacturers is that fail-over takes place in less than a second so there is virtually no loss of either machine control or data."
TCO is central
There’s no doubt that centralized maintenance, and re-use and deployment of existing applications are the biggest benefits of thin clients.
Cost reduction is at the top of most manufacturers’ goals, and if each operator has a dedicated PC and associated applications, maintenance potentially becomes a major headache for IT personnel, says Intellution’s Donaldson. For example, he says, any time an operating system or application software must be upgraded, IT personnel must make those changes on a PC-by-PC basis.
"Centralized administration represents a huge cost and time savings because personnel don’t have to walk all over the plant making upgrades," says Donaldson. "Additionally, it isn’t necessary to create a new HMI screen for each new thin client on the shop floor, which saves considerable resources."
By far, centralized administration is the most noteworthy benefit of Terminal Services thin clients, agrees Richard Consoli, president of Innovative Controls, a Knoxville, Tenn.-based systems integrator. But the ability to quickly and efficiently upgrade software isn’t the only issue associated.
"In pharmaceutical and other industries governed by FDA [Food & Drug Administration] mandates, upgrading software is much more complex," Consoli says. "Each PC’s software must be upgraded, but then each must also be validated to ensure it works as it should. The ability to make a change to one server instead of numerous PCs is substantial."
From pure TCO concerns to additional benefits of centralized deployment such as auditing software upgrades, Terminal Services promises to help manufacturers do more with less. That’s a pretty compelling argument for a technology in today’s economic climate.
| FOR MORE INFO: | ||
| Automation Control Products : www.acpthinclient.com | Intellution : www.intellution.com | Microsoft : www.microsoft.com |
| Rockwell Automation : www.automation.rockwell.com | USDATA : www.usdata.com | Wonderware : www.wonderware.com |
