The Wired Home: Part 7 of 12

The Wired Home: Part 7 of 12

Design a home automation system that helps your customers get the most from their home technology investment Many of us dream of the day when our homes become truly automated, and walking, talking robots handle the menial day-to-day tasks of cooking and cleaning. Although we're not quite there yet, the key to home automation, or home technology integration, is making diverse subsystems work together

Design a home automation system that helps your customers get the most from their home technology investment

Many of us dream of the day when our homes become truly automated, and walking, talking robots handle the menial day-to-day tasks of cooking and cleaning. Although we're not quite there yet, the key to home automation, or home technology integration, is making diverse subsystems work together seamlessly. As the seventh installment in a 12-part series that will prepare electrical contractors to take the exam to become home technology integrators (HTI), this article will discuss the infrastructure that supports all home automation hardware and software. The infrastructure can be classified under one of these six categories: structured wiring, structured media center (SMC), control processor, user interface, home portal, or residential gateway.

Structured wiring.

The infrastructure for integrating home automation components begins with a plan for wiring each subsystem. This plan allows for the sending and receiving of information and commands between control processors, sensors, and activation modules. During this phase of the project, it's important to remember that low-voltage structured wiring cables can't be bundled with AC electrical service wiring. Not only does this bundling violate building code requirements, but electromagnetic interference almost guarantees poor performance of the networking, communications, and entertainment systems.

Your choice of cabling is also important to overall system performance. Let's quickly review your options in this area.

Cat. 3 cable — Cat. 3 cable and connectors are certified for up to 16MHz of bandwidth, making them suitable for voice and low-speed (10 megabits-per-second) computer networking. It is important to note that Cat. 3 specifications allow for up to 3 in. of untwisted wire at each termination point.

Cat. 5 or 5e cable — Cat. 5 cable and connectors are certified for signals like Ethernet with up to 100MHz of bandwidth, making them the preferred choice for all computer-networking installations. Cat. 5e copper cable is an enhanced copper specification certified to 1 gigabit-per-second data transfer. The rule in copper cable bending radius design is to bend the wire to a curve no less than four times the diameter of the cable. Some home-automation sensor and command systems use two- or four-conductor cables for signal transmission. Cat. 3 or Cat. 5 cable can serve as transmission wire in all of these systems.

Coaxial cable — Coaxial video cable is the standard and must be included in any structured wiring installation. RG-6 coax cable should be used for high-bandwidth applications encountered in most residences.

Fiber-optic cable — Entertainment and computer networking systems could move to fiber-optic cabling in the future. When installing fiber-optic cabling, the home technology integrator (HTI) must comply with the cable termination and bend radius requirements. Optical fiber cable requires a gentle bending radius that is a minimum of 10 times its diameter, which protects the cable's integrity and high-performance characteristics.

Structured media center (SMC).

The structured media center (SMC), otherwise known as the distribution device (DD) or distribution panel, is the point in the system where all of the structured wiring infrastructure is eventually terminated. The SMC is typically a metal box in which controlling components of each subsystem are housed for interconnection or cross-connection. The SMC configuration depends largely on the number of devices and types of equipment the network will support. It's typically configured as the center of the network in a star topology layout. All devices in the system have home run cables with direct channels to the SMC. The auxiliary disconnect outlet (ADO) is housed within the SMC. This provides the homeowner with the capability to unplug the network from the access provider, or local exchange carrier, network, if the need arises.

The typical recommendation for a single-family residence is for one SMC to have sufficient capacity and functionality to accommodate the following minimum system requirements:

  • Cat. 5e data distribution.

  • Cat. 5e telephone distribution.

  • Coaxial Series 6, or quad-shield, cable for video distribution.

Another important termination point on the system is the network interface device (NID). The NID is a box located on the exterior of the house, often mounted near the electrical meter. There are two sides to the NID: the homeowner side and the telecommunications company side. The point where the two sides meet is known as the demarcation point, or demarc. If a problem occurs on the telecommunication company's side of the demarc, they're responsible for its repair. But if the problem is on the homeowner's side of the demarc, the homeowner or the HTI is responsible. In older installations you may find a protector block instead of an NID. A protector block is a small, plastic-covered box in which the cable coming out of the house connects directly to the telecommunications company's cable. The protector block serves the same purpose as the NID.

Control processor.

The control processor, or CCU, is considered to be the brain of the system. As such, it must have sufficient input and output capacity to deal with the various controlled subsystems, and sufficient processing power to keep the programs running. It's most convenient to locate the control processor in the SMC.

Configuring the control processor is as much a procedure of software as of hardware. You should ensure that software requirements, such as the processor speed, RAM, and hard drive capacity, can be accommodated by the hardware available in the system design. One of the more crucial areas for configuration involves checking to make sure that control software is communicating properly with the I/O port used for control of the particular subsystem. Serial ports must be matched to the transfer rate, flow control type, and data configuration of the controlled application subsystem.

Once I/O ports are configured, care must be taken to ensure that software is communicating only with the ports designated. In a simple system with only one control medium — for example, in a system using X-10 control modules, to which the control processor communicates via an RS-232 serial port — this is a straightforward task. In more complex environments — those that see the control processor communicating with various systems through RS-232, RS-485, Ethernet, and parallel ports — keeping signals and interrupts straight can be the subject of significant debugging time.

The control processor should also be protected by an uninterruptible power supply (UPS) that guards against long reboot times and lost data in the case of a power outage.

User interfaces.

Integrated user interfaces can encompass computer terminals, wall switches, or cell phones. Although integrated systems can have multiple user interfaces, the primary motivation behind the integration of multiple systems is the capability to have a single user interface through which all major home systems may be controlled.

Many installations use a Microsoft Windows interface for control of complex integrated systems. Microsoft Windows XP is one such user interface. Windows XP makes home automation simpler for the homeowner to manage because it's familiar to many existing computer users. Windows CE is designed for implementation on mobile, handheld, and other space-constrained devices that are suitable for deployment as automation controllers.

Wall switches and panels are also popular choices for installations because they offer immediate control, typically at the point of use. In more complex interface systems, you must ensure that input from one device is reflected to other input mechanisms in order to avoid potential conflicts.

Handheld remote control units are common for integrated automation applications. These devices frequently provide the advantages of lower cost and easier programming, but these handheld devices can't offer the context-sensitive buttons and menus offered by a standard keyboard.

Complex systems must be controlled through interfaces that are straightforward, unambiguous, and easy to learn. One of the most common and effective methods is to combine multiple system states into complete scenes, combining lighting levels, HVAC settings, and A/V commands. It's important to build scenes and control combinations carefully, testing each controlled aspect fully before adding the next. Confusion between control points can result in unanticipated device behavior and unsatisfied homeowners.

Home portal. Many homeowners who are comfortable with the Web are eager to control their home systems through their personal computer's Web browser. Integrated home automation systems can provide a Web browser interface through the use of a residential portal, which takes the command structures of the automation systems and translates them into control codes that can be understood by a browser. To set up the home portal for your customers, you need to install a Web browser and portal software on their PC. The Figure shows an example of a simple home portal with icons.

The first requirement for a home portal is the installation of a Web server. An application must then take the home automation control and sensor data streams and translate them into information that can be displayed on and acted upon by a Web browser. It's most cost effective to purchase a PC or Macintosh program that bridges the gap between automation and the Web. For example, HomeSeer works with the PC for X-10 technologies and offers a free 30-day trial.

You must consider several key factors when choosing a portal for a residential customer. Primarily, you should ensure that the portal will provide compatibility with all devices in the home. The portal must also be secure and optimized for the browser that is most likely to be used by the homeowner. Home portal products may offer varying functions, but all operate within the familiar interface of a Web browser.

Configuring the home portal requires dealing with several aspects of the application:

  • Connection between portal and controlled systems — If the installation is built around a common command protocol like X-10, many portals may come preconfigured for control. If the installation uses a less-common protocol, make sure that the correct command set is included in the software you choose to use.

  • User interface — The basic user interface for a home portal has the same appearance as the Web browser on the user's computer. Within the browser window, however, some customization is available and sometimes required.

  • Connection between portal and other computer applications — Many portals come with the control application and Web server integrated into a single package. These portals keep software integration and programming efforts to a minimum.

  • Security — Security becomes an issue with portals in two cases. First, if the portal allows access to individual device control and scene reprogramming, these advanced development sections should be password-protected to keep curious guests and mischievous children from wreaking havoc on the home environment. Second, if the home portal is on a standalone computer or server appliance, it connects to the control processor, the residential gateway, and other computers through a standard computer networking protocol like Ethernet in either 10-Mbps or 100-Mbps speeds. A residential gateway is required if the portal needs to be accessible from the Internet.

Residential gateway.

In an integrated automated residence, the control of the home is open to those outside the home at several points. The points of access can include a telephone line, a fax line, or a broadband Internet connection. A residential gateway connects multiple computers in a home to a single Internet connection and connects all internal home networks to their external counterparts. Without a residential gateway in place, no security or control exists between the residential network and the outside world. The gateway can also include software that limits the activity of family members to acceptable Web sites and content.

You can think of a residential gateway as the software answer to the structured wiring closet. The main functions of the residential gateway are control and security. Gateways block unauthorized access to the home and they can control content access of minors.

Simply plugging in the various cables and turning them on configures many gateways. The appliances come preconfigured with the options most users will need. In other cases, the aspects of computer networking need to be understood to best configure the gateway.

If gateway configuration is required, you should be trained to understand how TCP/IP (Transfer Control Protocol/Internet Protocol) addresses are assigned, and whether you need to assign each computer and network device its own individual address or allow the addresses to be assigned automatically by the gateway. In either case, security dictates that you assign each device an address that is non-routable in an addressable space — in other words, it can't easily be fooled into believing that an outside computer is actually part of the inside network. Assigning an address in the or the space should be safe.

Testing and documentation.

As a final step in designing and setting up a home automation system for your customer, you must thoroughly test the system to ensure it performs as designed. Test each individual component of the system. Next, test each subsystem. Finish up with a comprehensive test of the entire system. Remember, when complex scenes are programmed into an integrated home, subsystems should first be tested alone, then in pairs, and finally as complete scenes. If problems are detected, determine their nature, fix them, and document the repairs.

It's important to keep a careful record of each problem encountered during the installation and of any changes made. Record the reason for the change or repair, the person who conducted it, the time and date, and the complete details. Although tedious to make, these records provide valuable information if subsequent changes are necessary.

It's also important to accurately document how each individual subsystem in the controlled residence is set up and what exactly its function is within the overall system. It's even more important to document how the various subsystems connect to one another. You should also document all software-related issues like noting the specific name and version used during the installation.

Documenting the layout of cables and arrangement of equipment is another crucial step in the documentation process. Label photos of equipment racks with equipment names, cable runs, and other pertinent information. Where cables can be separated by jacket color or connector type, these distinctions should be listed and made clear in the documentation. Photos labeled with information on which equipment is connected and diagrams reinforcing the information in the photos can make future wiring changes more certain and less time consuming.

You should also list power connections on the wiring guide and label connectors at the AC connection end. Technicians and homeowners will then have a clear understanding of the consequences of unplugging a particular cord or turning off a specific power strip.

Home automation technology hasn't become a mainstream fixture in the majority of homes today, but it won't be long before the popularity and affordability of this technology takes hold.

Dusthimer is publisher of Cisco Learning Institute Press, York, Pa.

Sidebar: Who Wants to Be an HTI?

Electrical contractors can now become certified as home technology integrators (HTI). CompTIA, in conjunction with the Internet Home Alliance and a cornerstone committee of Fortune 1,000 companies, has developed a two-exam certification process. The material in this 12-part series is part of a 50-hr training program designed to prepare individuals to take the HTI+ certification exam. Throughout the year, the articles in this series will include excerpts from the HTI+ training program developed by the Cisco Learning Institute along with industry partners Leviton Manufacturing, HAI, Premise, Interlogic, and Bluevolt. This program will prepare electrical contractors and their employees to capitalize on this new and financially rewarding segment of the field.

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