Z-Wave improvement
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Posted by Dave Houston on March 13, 2007, 8:27 am
Please log in for more thread options 2006) but it is just now starting to ship. It addresses two Z-Wave weaknesses which I have been pointing out for the past 3 years or so. http://www.intermatic.com/images/news/InTouch%20Launch%20Release%20Final.pdf First, it increases the maximum number of hops a message can take from 4 to 8. Given that Z-Wave devices need to be within 20-25 feet of each other to assure coverage, 4 hops severely restricted the size of any Z-Wave network and I considered it a fatal flaw in the Z-Wave system. 8 hops is a much more realistic figure. Second, it employs what Intermatic calls a "server" which is in the base/charger for the handheld remote. It periodically polls all of the devices (including legacy Z-Wave devices) in the network and maintains a status table which can be accessed by other controls. http://www.intouchcontrols.com/intouch-technology.php I still have some questions and haven't been able to find in-depth technical details to answer them. 1. How often is the network polled? The polling frequency will determine how up-to-date the status table is but frequent polling may hamper operations by causing collisions with user generated signals. 1a. Can legacy controllers access the "server"? 2. It's not clear how legacy devices will deal with the increased number of allowable hops. The remaining hops are embedded in the message and it's not clear how legacy devices will deal with numbers greater than 4. Perhaps the original protocol anticipated larger numbers. Intermatic says they've applied for patents so their approach may or may not show up in other Z-Wave systems. Prices for InTouch(tm) devices are approximately 3x those of comparable devices in Intermatic's HomeSettings(tm) line of legacy Z-Wave products. http://www.automatedoutlet.com/home.php?cat=247 http://www.automatedoutlet.com/home.php?cat=236 Intermatic has started a forum where those interested can get answers to their questions. http://www.intouchcontrolsforum.com/forums/ Finally, I don't know how microwavable it is - it uses the 900MHz band in North America. http://davehouston.net http://tech.groups.yahoo.com/group/roZetta/ roZetta-subscribe@yahoogroups.com | ||||||||||||||||||||||
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Posted by Robert L Bass on March 13, 2007, 11:17 am
Please log in for more thread options It is quite common in the industry for manufacturers to announce new product designs some time before they are ready to ship. This allows distributors and dealers to become familiar with the product in advance so that they can build a market for it by the time it actually ships. Mr. Houston announced his own products long before they were ready to ship. > First, it increases the maximum number of hops
> a message can take from 4 to 8... I think I said exactly the same thing. > Given that Z-Wave devices need to be within
> 20-25 feet of each other to assure coverage... That is misleading information. The following is from an article by Mikhail T Galeev of Embedded Systems Design: "Each Z-Wave network may include up to 232 nodes and consists of two sets of nodes: controllers and slave devices. Nodes may be configured to retransmit the message in order to guarantee connectivity in multipath environment of residential house. Average communication distance between two nodes is 100 feet, and with message ability to hop up to four times between nodes, it gives enough coverage for most residential houses." Further, according to a study run by EURASIP Journal onWireless Communications and Networking, "The Z-Wave communication protocol allows a maximum number of hops in the network. Because of the protocol design, it has to handle communications in a home environment, and consequently, it does not need to communicate data over long distances. The communication range in a free line-of-sight scenario is about 70m, but it can fall down to 15-20m in an indoor environment. However, Z-Wave nodes belonging to the series 100 and series 200 allow a maximum of four hops, so that the overall communication distance which can be covered in an indoor scenario is about 100m." This study found that even the standard, pre-Intermatic Z-Wave systems can handle homes up to 330' long with the controller mounted at one end. With the controller in the center, a Z-Wave system could handle a home that is over 600' long. > 4 hops severely restricted the size of any
> Z-Wave network and I considered it a fatal > flaw in the Z-Wave system... Actually, it is far from a fatal flaw. The system is far more powerful than Mr. Houston allows. > 8 hops is a much more realistic figure...
Eight hops allows Z-Wave to service even larger homes and office environments. > Second, it employs what Intermatic calls a
> "server" which is in the base/charger for the > handheld remote. It periodically polls all of the > devices (including legacy Z-Wave devices) in > the network and maintains a status table > which can be accessed by other controls. This answers one valid objection to Z-Wave which several other participants have mentioned. The system can now know which lights and appliances are on, off or dimmed. > I still have some questions and haven't been
> able to find in-depth technical details to answer > them. > > 1. How often is the network polled? > 1a. Can legacy controllers access the "server"?
The server will recognize signals sent by legacy controllers to operate legacy devices. However, they will not be able to control the server. That's largely unimportant though, since the InTouch server obviates use of legacy controllers. > 2. It's not clear how legacy devices will deal
> with the increased number of allowable hops. Legacy devices can travel 4 hops. InTouch devices can go 8 hops. > Intermatic says they've applied for patents
> so their approach may or may not show up > in other Z-Wave systems. The Z-Wave protocol is licensed by InTouch and over 100 other manufacturers. Using Z-Wave protocol, anyone can develop a system that handles 8 hops and polling. > Prices for InTouch(tm) devices are approximately
> 3x those of comparable devices in Intermatic's > HomeSettings(tm) line of legacy Z-Wave products. Better products cost more. However, you can expect online discounters to keep prices in line. > Intermatic has started a forum where those
> interested can get answers to their questions. > > http://www.intouchcontrolsforum.com/forums/ The forum is brand new. There's only one 2-message thread in it as of this writing. > Finally, I don't know how microwavable it is
> - it uses the 900MHz band in North America. Set the microwave on medium for 30 seconds with the turntable set to OFF. Be careful to remove aluminum foil from the product before turning on the microwave. :^) -- Regards, Robert L Bass =============================>
Bass Home Electronics
941-925-8650 4883 Fallcrest Circle Sarasota · Florida · 34233 http://www.bassburglaralarms.com =============================>
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Posted by Bill Kearney on March 15, 2007, 3:43 pm
Please log in for more thread options
> It is quite common in the industry for manufacturers
> to announce new product designs some time before > they are ready to ship. Uh, isn't that de rigueur in the home automation sector? I mean, there's a long history of announcements that never come to fruition, so why break the trend now? | ||||||||||||||||||||||
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Posted by Robert L Bass on March 15, 2007, 4:40 pm
Please log in for more thread options > Uh, isn't that de rigueur in the home
> automation sector?... From what I can see it appears this is SOP in most industries. > I mean, there's a long history of
> announcements that never come to > fruition, so why break the trend now? In this case the announced products have indeed come to fruition. I guess that breaks the trend, no? :^) -- Regards, Robert L Bass =============================>
Bass Home Electronics
941-925-8650 4883 Fallcrest Circle Sarasota · Florida · 34233 http://www.bassburglaralarms.com =============================>
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> Z-Wave based system a year ago (March
> 2006) but it is just now starting to ship...