It has been a little over one year since the ratification of the ZigBee specification (December 2004), and the subsequent announcement on April 1, 2005 of four ZigBee-compliant platforms from Chipcon, CompXs, Ember and Freescale Semiconductor. Based on the recent and planned introductions of several ZigBee-based end products, the standard is starting to gain traction. The ZigBee Alliance has more than 200 Alliance Members and a presence in 24 countries on six continents. With OEMs and end-product manufacturers representing 30 percent of the global membership, ZigBee promises to enable new features in several leadership products.
This means homeowners will be able to buy off-the-shelf products that work together in a networked environment. In addition, heating, lighting and security systems in homes equipped with ZigBee-based networks can be easily reconfigured. In building automation, wireless monitoring networks with centralized management of lighting, heating, cooling and security systems will provide the flexibility to reconfigure systems to adjust for occupancy changes within a building.
What's a ZigBee?
Developed for low-rate personal area networking, ZigBee is a standards-based technology designed to address the unique needs of low-cost, low-power, wireless sensor networks for remote monitoring, home control and building automation network applications. The technology allows digital transmissions of up to 1 Mbps in the 868 through 928-MHz band or 2.4 GHz. To keep the power requirements low, the expected range is from 10 to 70 m. Using the IEEE 802.15.4 standard as a foundation, ZigBee's mesh network topology transmits a signal through redundant pathways providing improved reliability for wireless sensing and control.
The key to ZigBee's future growth is interoperability. Manufacturers, OEMs and developers can qualify products for one of three levels:
ZigBee Compliant Platform modules or platforms that are intended to be used as building blocks for end-products.
ZigBee Certified end-products built on a ZigBee Compliant Platform using a ZigBee public application profile.
ZigBee Network Capable products built upon a ZigBee-compliant platform, but using a non-public ZigBee application profile.
The reasons for selecting ZigBee over other wireless options are the same in most cases. Maura Turolla and Elisa Alessio of Telecom Italia summarized the reasons quite nicely in their presentation at the recent ZigBee Open House in Milan, Italy. Compared to other proximity radio technologies, such as RFID, Near Field Communication (NFC), and contactless, as well as Bluetooth, the main key-values driving the ZigBee choice are:
Pervasive Ad-hoc Self-organizing Mesh Networks (not limited to star topologies)
Configurable Radio Range
High Security Level
Easy integration in appliance/terminals in miniaturized peripherals with integrated antenna
About the only ZigBee differentiators missing from their list were low cost per node and low power for longer battery life. Some applications may take advantage of just a few of these. ZigBee MomentumThere have been a few surprises in the end product activity over the past year. One is in the area of automatic meter reading — an initial target application for ZigBee. "The surprise is that (automatic meter reading) seems to be moving faster than I anticipated," says Bob Heile, chairman ZigBee Alliance. "Both the carriers and the utilities are seeing the future benefits of having a meter reading technology that can ultimately become a control technology." Automatic meter reading, combined with building control functions, allow load-shedding with minimal disruption and avoid performance penalties for brown-outs and black-outs. In addition, the combination allows handling peak power for a limited number of hours each year without adding new capacity that would be largely underutilized all the rest of the time. This provides a rather straight-forward and compelling solution to a very complex problem. For example, in commercial buildings with extensive deployment of ZigBee-based lighting controls, the lighting can be dimmed by 5 percent to handle a peak power situation based on the automatic meter reading input and the system's capability to control ZigBee-certified lighting. The 5 percent dimming would hardly be noticeable to building occupants. Heile says these systems are in the design and evaluation phase in the U.S. and other regions. The following five products and/or systems show the real power of the low-power ZigBee network. They are either currently or eminently available. 1 Home Theater ControllerAVM-HTC1-B Control4http://rbi.ims.ca/4922-564 Control4 began shipping ZigBee Network Capable products in April. In addition to the theatre control of home audio and video equipment, the system includes wireless control capability to automate and remotely control several functions in the home. The wireless products can be easily retrofitted into the home to provide reliable, cost-effective control. Control4's systems approach includes wireless lighting, control systems, wireless dimmer, wireless outlet switch, remote HVAC controls, and servers for video and audio with control pads located around the house. ZigBee remote controls with displays interact with the system and ZigBee controls the entire infrastructure. The system uses optical fiber CAT5 and 802.11 for distributing wideband content. At the same time, the home theatre sets a predetermined lighting mode. The same system handles security from a central (or remote) control. The system's communications include:
Wireless ZigBee (802.15.4) mesh networking
Ethernet (802.3) 10/100base-T, RJ45 jack
WiFi (option) 802.11
The system has multiple interfaces including Touch Screens, Keypads or the System Remote Control. Control of products located throughout the home occurs by IP-based communication over wireless 802.15.4 mesh networking or Ethernet. Specific ZigBee control products include the Wireless Outlet Dimmer that controls plug-in devices rated up 500 watts and the Wireless Outlet Switch that controls plug-in devices rated up to 15 amps. 2 Home AutomationHome Heartbeat Eatonhttp://rbi.ims.ca/4922-565 The Home Heartbeat uses a variety of sensors to monitor several functions and keep track of the home environment. The ZigBee-ready system consists of three basic components: sensors, a base station and a Home Key device. The base station receives the input from the sensors and determines the appropriate action. The Home Key device provides a removable display for the base station and a portable sensor monitor to display every function in the system. In addition, the key is the interface used to set up the system. A Water Sensor detects the presence or absence of water making it ideal to identify flooding. If water is detected, the Water Shut-Off Valve can turn off the main water supply line. Reminder/Timer Sensors provide a reminder to check items around the house or to perform a specific task on a regular basis, such as changing an air filter. Open/Closed Sensors identify an open window or garage door. The Power Sensor sends an alert if an appliance or electric device has been inadvertently left on. The Attention Sensor provides an immediate contact, like an instant messenger for the Home Key device. Planned additions to the system's capabilities include motion, gas detection and temperature sensors. The ZigBee protocol allows the easy addition and reconfiguring of these sensors. 3 Wireless Home AutomationHomeRemote Hawking Technologyhttp://rbi.ims.ca/4922-566 With planned availability in July 2006, the HomeRemote System addresses new or existing home networks with ZigBee-ready wireless control. For homes without an existing home network, the Wireless Home Automation Gateway, which includes a Wireless-G router, provides wireless access for HomeRemote devices and sensors and WiFi Internet access for other networked computers. The gateway shares one broadband Internet connection among all the computers. For homes with an existing network, the Wireless Home Automation Hub provides wireless communication with HomeRemote devices. System components include:
Wireless Door/Window Sensor that detects the opening and closing of windows, doors, cabinets, pet doors
Wireless Power Outlet, a controlled power outlet for lights, televisions, computers, heaters or fans
Wireless 7-Outlet Power Strip has seven outlets for controlled power
Wireless Signal Extender that extends the wireless coverage area for the system for larger homes or remote, onsite buildings
With the future availability of items such as Wireless Cameras, Audio Monitors, Sirens and Strobe lights, Motion Detectors, and Local Control Panels, the HomeRemote will tie a number of ZigBee nodes together. 4 PDA CF CardCF card Telegesis http://rbi.ims.ca/4922-567 Telegesis is shipping initial quantities of its ETRX1CF, a ZigBee Network Capable Compact Flash (CF) type II card for PDA or portable computer applications. The unit enables a portable handheld product to communicate with other ZigBee modules. The node can be used in a PDA with a CF slot or in a laptop computer with a PCMCIA/CF adaptor. Telegesis provides drivers and support for Pocket PC and a simple terminal application program as a starting point for developers. Telegesis-developed software allows the CF card installed in a PC to function as a ZigBee development board using AT-style commands. Example commands include AT+SN (search ZigBee network and discover devices), AT+MCAST (sends a multicast), AT+BCAST:
(sends a broadcast), and AT+ASS:
(associate node). Similar to many WiFi PCMCIA cards, the antenna resides in the extension of the card, which is external to the PC or PDA.
5 Gas Detection SystemWireless Gas Monitor Vulcainhttp://rbi.ims.ca/4922-568 Designed for parking structures, this industrial system identifies hazards and triggers the appropriate reactive measures such as ventilation activation. The VA301W wireless gas monitor uses electrochemical sensors to detect carbon monoxide (CO) and nitrogen dioxide (NO2) and operates for two years without calibration, maintenance, or battery replacement. The sensor's data is transmitted to the VA301C-W controller over a ZigBee-ready network with a secure 128-bit encryption. The VA301C continuously monitors up to 96 inputs/outputs, on three distinct channels, at distances of up to 2000 feet. The controller's zoning capabilities permit the averaging and comparison of multiple sensor readings. For the output control, the VA301R transmitters/relay module provides up to eight relays of 5A, 30 V dc or 250 V ac (resistive load) to activate fans, louvers, and other devices at programmable alarm levels. The unit's Modbus output can be converted to a BACnet output. The ZigBee wireless sensors allow the installation at a substantially reduced. In addition to avoiding the wires, the mesh network provides auto configuration. The low-power protocol also means reduced operating expense since the batteries can last for two years without replacement.
For industrial control applications, or even a simple assembly line, that machine can go almost 24/7 without a break. But what happens when the task is a little more complex? That’s where the “smart” machine would come in. The smart machine is one that has some simple (or complex in some cases) processing capability to be able to adapt to changing conditions. Such machines are suited for a host of applications, including automotive, aerospace, defense, medical, computers and electronics, telecommunications, consumer goods, and so on. This discussion will examine what’s possible with smart machines, and what tradeoffs need to be made to implement such a solution.