Building Automation: An Alliance Takes Flight
"Mission: The ZigBee Alliance is an association of companies working together to enable reliable, cost-effective, low-power, wirelessly networked, monitoring, and control products based on an open global standard.
"Objective: The goal of the ZigBee Alliance is to provide the consumer with ultimate flexibility, mobility, and ease of use by building wireless intelligence and capabilities into every day devices. ZigBee technology will be embedded in a wide range of products and applications across consumer, commercial, industrial and government markets worldwide. For the first time, companies will have a standards-based wireless platform optimized for the unique needs of remote monitoring and control applications, including simplicity, reliability, low-cost and low-power."
I first introduced the 'Bee word in my June ES column, but the interest just keeps building on our website about this new alliance. To catch all the buzz (sorry the name is just too much fun to leave alone), type the word ZigBee into either one of our website search engines (www.automatedbuildings.com/search/sitesearch.htm). You will be amazed at the amount of folks talking about these new 'Bees.
An article in our December issue titled "ZigBee or Not ZigBee" by Guy Zebrick of Kele Inc. (www.automatedbuildings.com/news/dec04/articles/kele/zebrick.htm) provides insight to the connection of this new standard to our industry. Several excerpts from the article follow.
The building automation market has seen the emergence of a new class of affordable, reliable, commercial-grade, RF (radio frequency) enabled devices. These wireless devices can reduce traditional electrical contracting costs associated with difficult installations of HVAC I/O (heating, ventilating, and air conditioning inputs and outputs), and by using digital technology, these new systems eliminate many of the headaches and uncertainties associated with older radios. In order to standardize the implementation of digital radio telemetry across many markets, including commercial HVAC controls, the ZigBee organization has formed. Will ZigBee standardization fulfill every promise offered by the latest in radio technology?
There's ZigBee, and Then There's ZigBeeIt is the intent of the ZigBee alliance to provide seamless plug-and-play functionality between devices from different vendors. However, it remains to be seen if true plug-and-play interoperability will ever be achieved. The recent examples of BACnet, XML, and Echelon LON interoperability may provide some history on the likelihood of a single, universal, agreed-upon standard for network management, point, and device profiles. Once ZigBee devices are available, compliance to the ZigBee standard will also have to be formalized. Some sort of independent testing and certification system should also be in place to assure seamless interoperability between all devices. ZigBee certification may even allow for different levels of compliance, further complicating interoperability efforts.
Get off my bus!There is another issue regarding cooperative MESH networking beyond the technical and market challenges. Once an installing contractor designs and establishes a finished ZigBee network, perhaps very carefully optimizing device transmission times and node routing and locations for a specific application, it might be unreasonable to expect that a second contactor would even be welcomed to hop onto the installed MESH. The addition of unexpected ZigBee devices suddenly jumping onto an existing ZigBee network could be very problematic, especially if the original network suddenly starts to have trouble and finger pointing begins.
A Real MESHRight now, state-of-the-art proprietary systems provide the best, and in some cases, the only practical solution for many wireless HVAC I/O applications. The very latest of these also share many of the same technical advantages of ZigBee, including interference-free direct-sequence spread-spectrum transmission and even MESH and MESH-like repeater network protocols. These digital systems provide reliability, performance, and useable range, along with advanced transmitters capable of a two- to five-year battery life. Another plus is that many of the current wireless systems include gateway devices for interfacing into today's most common HVAC communication protocols including, but not limited to, Echelon's LON, Modbus or BACnet.
ZigBee, once available, should make possible some level of interference-free and cooperative communication between and through multiple manufacturers, but there is no guarantee that devices provided by different manufacturers will be able to share data. Trying to get a multitude of manufacturers' ZigBee devices, installed by various contractors, operating on many different radio bands, and using different networking modes to all work together and share data on a single radio network could wind up being a real MESH. ES