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Updated February 26, 2007 07:00 PST

What kind of security is on the Z-Wave system? How do I prevent an external source from turning on or off lights or systems?
Each Z-Wave Primary Controller ships from the factory with its own unique house code, no two are alike - unlike legacy systems that reused house codes from a small pool of 256 possible codes.

All devices that are installed in your home will get their own device addresses and unique house codes from that Primary Controller. This process is called Inclusion. In order to include a device into your home system you must have physical possession of the Primary Controller and you must have physical possession of the device you wish to include.

During the inclusion step the two devices need to be in close proximity to each other, no more than 10 feet apart, and you must press a button on each device to establish the connection and transfer the unique house code from the Primary Controller to the device. Once this inclusion step is performed the device will only respond to other devices that share the same home code. There is no way for your next-door neighbor to control or modify your system.

Can you buy Z-Wave chips to create your own hardware for items that don't exist yet or is the Z-Wave more of a protocol and not a hardware solution?
Z-Wave is both a protocol and a hardware solution. To create Z-Wave products you purchase a System on a Chip or SoC from Zensys. This SoC contains the physical radio, a microcontroller, and the Z-Wave protocol stack or software.

Unless you are an OEM hardware manufacture, you would most likely start with a complete Z-Wave transceiver from a Z-Wave OEM such as an Intermatic USB stick and build out your application from there. There are software developers' kits (SDK's) available for PC and for .NET devices.

Is there open source code for Z-Wave?
Absolutely. Some of our vendors have embraced the open source and hobbyist communities extensively. For example, many free projects have cropped up using the Intermatic/Microsoft HA102 starter kit (with the ControlThink Z-Wave PC SDK). The xPL project also provides open source support for Z-Wave products.

Z-Wave is a multi-vector broadcast system. How does it prevent flooding?
Z-Wave is not a multi-vector broadcast system. Instead, it is designed based on a highly efficient source routing algorithm. Therefore, typical problems associated with flooding are irrelevant for Z-Wave. In this regard it is very different from technologies such as ZigBee, AODV, Insteon, and KNX RF that are using flooding-based algorithms for all route resolution or even for the transmission of every single command.

The expert panel includes Mark Walters, vice president, Z-Wave Alliance; Chris Walker, president and chief software architect of ControlThink, and ZWW contributing editor, David Powell.


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