Control Systems: Fact And Fiction

What you think you know about control systems may be wrong. Test your knowledge, and pick up some pointers. 5/30/2005 9:28 PM Eastern

Control Systems: Fact And Fiction

What you think you know about control systems may be wrong. Test your knowledge, and pick up some pointers.

Ever since the advent of control systems, myths have surrounded their design and functionality —possibly because their origins are frequently as varied and dubious as the myriad of control protocols and interface “standards” that make AV professionals' lives so interesting. The continued proliferation of such misconceptions can not only cause serious confusion for prospective clients and system designers alike but also annoy industry veterans that should know better. To see how well you can identify fact from fiction on the control system front, take this quiz.

1. Control systems are too expensive.

Fiction: In actuality, it's the AV system that's too expensive if left unused because it's unreliable or difficult to operate. A control system adds value by increasing productivity and reducing downtime by making the complete system user friendly.

Many of today's low-cost and multipurpose product options may not have existed when this myth got started. For instance, new integrated presentation solutions continue to further expand the many capabilities a control system can offer, while simultaneously delivering cost-efficient solutions to suit applications of virtually any size or budget.

For little or no cost, a software-based central help-desk management solution can significantly reduce client operating expenses that relate to room setup time, equipment failure, and user error — effectively paying for the control system in return over time.

2. I should specify a large processor in anticipation of future needs.

Fiction: With the variety of control system sizes and feature sets now available on the market, combined with native master-master and master-slave networking capability, every system is now essentially scalable. Therefore, it's not only practical but also cost effective to purchase the exact system you need now — knowing you can easily expand and upgrade it later.

You must also consider the life span of a typical control system. As with computers, the technology employed in a control system will eventually be supplanted by newer, more powerful technology. Foresight and ongoing firmware development on the part of the control system manufacturer can help maximize the system's practical life span, but as technology and the client's needs evolve, a hardware upgrade will be necessary eventually. As such, it would be unwise to install a large card frame in anticipation of a possible expansion five years later.

3. The GUI is the challenging part.

Fact: For touchpanel-based control systems, the graphical user interface (GUI) is often the only component end-users see or touch — as it's the user's primary point of interaction with the system. Therefore, it stands to reason that the quality of the GUI design largely determines the ultimate usefulness of the entire system.

Historically, in many firms, the same individual has created the touchpanel GUI and programmed all the underlying code and logic. Ironically, the psychology behind the design of these two elements can be quite different, and not all good programmers are good at GUI design. In fact, quite often a skilled programmer's sensibility of what's “logical” and “intuitive” can prove downright cryptic to a typical end-user.

As a result, it has become common practice today for many systems integrators to employ a dedicated professional graphic designer to focus on the more “human” needs of the project, leaving the programmer to concentrate on the more technical aspects.

4. IR control is bad.

Fiction: From a control interface standpoint, the primary downfall of infrared (IR) technology is the absence of true-feedback. The user likes to know if the projector is really on, the correct input is selected, and Chapter 3 on the DVD is really playing. All's fine if the user presses the right buttons and everything works, but we all know errors and complications crop up. Without true-feedback, the cause of failure can be anybody's guess in the heat of the moment.

Still, the hardware requirements for IR are simple and inexpensive. Because it's easy to learn codes and create custom drivers, it's only natural that IR continues to be the most common interface standard for most AV gear on the market. Fortunately, for many installations, hardware solutions such as current sensing and video sync sensing provide a perfectly suitable solution for critical feedback of device power status and input selection.

More and more, manufacturers are implementing bidirectional interfaces, such as RS232 and Ethernet. But typically this has come at a cost — and has only been available on high-end models. Although this may be changing, for now the choice of interface comes down to functionality versus cost. And IR remains a viable, and valuable part of that formula.

5. Control systems can't control everything.

Fact: To control any device requires a suitable hardware interface (IR, RS232, Ethernet, etc.) and a suitable communication protocol or the “language” spoken between the device and the control system. Few protocols are universal. In fact, most are proprietary to the device manufacturer. Whether or not the manufacturer wishes to publish or share that protocol is often the most complicating factor of all.

There's rarely an issue when using an IR-based interface. Most IR-controlled devices conform to a more or less universal standard, and the codes are easily derived from the manufacturer's remote.

Ideally, serial protocols typical of RS232 and similar interfaces are published in a manual or are otherwise available from the manufacturer. Occasionally, errors or other shortcomings can be found in a manufacturer's protocol, often limiting or disabling some or all of the device's control capability.

Still other protocols can be so complex or obscure that they become hostile to the control system environment. Many manufacturers develop such protocols to function solely as part of a closed, proprietary network or control bus with absolutely no intention for third-party control system integration.

While the proliferation of Ethernet and IP-based languages continues to open up new integration possibilities, the many complexities associated with IP networking continue to mount challenges for control purposes. Admittedly, in this ever-evolving environment — with so many parties in play — there are inevitably cases where constraints can occasionally prohibit or limit successful control.

Fortunately, more manufacturers from various industries are realizing the value of building control system compliance into their products. Today, most are eager to work closely with control system manufacturers to develop integration solutions that bring enhanced functionality and reliability to their products through the control system.

6. Implementing control over the client's LAN is a major headache.

Fiction: When Crestron announced the first Ethernet-capable control system seven years ago, there was considerable resistance from IT personnel everywhere. Two worlds truly collided.

That roadblock is long gone now. Today's systems are the product of years of experience working directly with those same IT professionals. And through the process, corporate and university IT and AV personnel have been brought together. In many facilities, these two once seemingly opposed departments now coexist in relative harmony, and control over the LAN has become as normal as shopping online on company time.

All of the major limitations that might have, at one time, prohibited the use of control systems on a given LAN have long been overcome. DHCP/DNS capability is now available to support dynamic addressing, and SSL encryption delivers the industry standard for security. Perhaps most importantly, the configuration of hardware and software for communication over the LAN is all manageable by IT personnel in a language they understand.

7. Networked control systems compromise LAN performance and security.

Fiction: The truth is control systems present no more threat to network security than any computer or other device on a LAN. Such divisive rumors as “firewall holes” have proliferated since the first Ethernet-equipped control systems were introduced, but they've never proved valid.

By utilizing embedded operating systems, running proprietary code, and employing SSL, today's control systems are immune to the vulnerabilities that plague the common computer. It stands to reason that the control system should be the least of IT's security concerns.

The same is true of network performance. Control systems actually create minimal traffic as compared to all the other data present on the typical LAN. When a facility elects to install a dedicated network or subnetwork for AV control, it's actually for the purpose of preventing an adverse impact to the control system's performance.

By its nature, the control system relies on near real-time transmission of its signals. For instance, when the operator touches a button on the touchscreen, that button is expected to respond with appropriate feedback, and the associated command is expected to be executed. Any latency will almost certainly cause frustration for the operator. For example, imagine an urgent audio-mute command delayed by a large printer job stuck in the pipe — even for a second. Regardless of the true culprit, which component do you think will get the blame? For this reason, it can be good practice to isolate critical AV control traffic from the rest of the network.

8. Building or expanding a control system is simply a matter of adding devices onto the touchpanel.

Fiction: If you've ever experienced a computer network that evolved over many years by simply adding new software, databases, and hardware along the way, then you know that simply adding “devices” doesn't always work. In this analogy, some databases don't share information; some software doesn't work on existing computers, and legacy systems often don't communicate with new networks. Similarly, control systems won't function properly or seamlessly, or with the desired speed or reliability, if devices are simply added on. Control solutions are integrated systems and must be properly designed and programmed to function as desired. Only an authorized programmer or installer should attempt to integrate new devices into a control system.

9. A control system doesn't require a touchpanel to be considered a control system.

Fact: While touchpanels offer the ideal user interface for a majority of control applications, they are not the only option available and may not always be the optimal choice.

Sometimes simpler is better. For surfing TV channels or music tracks, advancing slides, or navigating onscreen menus, a well-designed handheld wireless remote may offer a better solution. The ergonomics afforded by a compact, lightweight form factor and tactile pushbuttons allow the handheld remote to become a natural extension of the human body. Commands can be executed automatically without conscious thought or visual contact.

Accessibility is also important. It's often said that the “best” camera is the one you have with you. Similarly, a fixed touchpanel or misplaced remote is useless when you're away from the podium and need to mute the audio or power down the system on the way out the door. A simple, low-cost keypad may provide the perfect solution.

Web-based control, commonly referred to as “e-Control,” is also a hugely viable and affordable alternative to touchpanels. Technology exists today to afford strikingly touchpanel-like appearance and behavior right on the computer screen. Even wireless tablet PCs and PDA devices can be exploited to provide a ready, portable solution for special applications.

Of course, just as the computer has the potential to serve as an alternative to the touchpanel, the touchpanel also has the potential to supplant the computer. New generation touchpanels actually feature an embedded Windows operating system, affording native web browsing and extensive capabilities for digital media presentation without requiring a separate computer.

10. Control systems will not become obsolete.

Fact: With each new technology, control systems will continue to evolve to meet, or perhaps, drive customer expectations. They certainly won't become obsolete. As AV and environmental equipment become increasingly intelligent, and as new user features and capabilities emerge, the demand to control them or integrate with them will only grow.

Perhaps standalone, single-room control systems will become more the exception than the rule while more complex, integrated multi-room systems with campus-wide asset management and centralized help desks become more prevalent.

Control systems not only enable the remote control of devices and subsystems, but also provide the integration medium through which they all converge. Control systems will always exist to streamline — and put a friendly face on — the profusion of technology that pervades our lives.

Michael Frank is a consultant liaison and Dana Hood is a technical writer for Crestron Electronics in Rockleigh, NJ. They can be reached at and


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