How Z-Wave Works

How does Z-Wave Work?

As technology evolves, it comes as no surprise that in the near future, we may be using remote controls to accomplish the simplest of tasks around the house. But in fact, the future could be already upon us…

Z-Wave’s advanced wireless system already provides for this increased convenience, interacting with its devices through a fixed electromagnetic field. This easy-to-use system is reliable, safe and secure, and best of all, you can install it without the need for dedicated wiring.

So precisely how does it work? Let’s say you’re in your bedroom, and you remember that you need to close the garage door. You instruct your Z-Wave system to do so; the command shoots from your controller, to the hallway fire alarm, and then bounces to the kitchen light switch, and finally to the garage door. This is the mesh network that Z-Wave utilizes, and it happens all in the blink of an eye.

Mesh network

The main difference between Z-Wave and the radio frequency (RF) component of Insteon is that in the latter, all of the nodes repeat signals each time a signal goes through the system. This is a true mesh network.

Z-Wave nodes do not go through this process; instead the intelligent, on-board software selects a route for the signal, and only devices on that route will repeat. The system is efficient, fast, and reliable – and it’s even self-healing.

Self-healing mesh network

One Z-Wave network can include up to 232 nodes. To avoid collisions, nodes make sure that there is no ongoing messaging traffic within the network before they begin transmitting data. This is one of the main advantages of a self-healing mesh network, like Z-Wave, where no central or master controller is needed.

In a mesh network topology, a command from node A to node C (considering it is outside range) can be communicated through node B. If that is not possible, another route will be automatically attempted in order to reach node C. This will repeat until the signal somehow reaches node C, no matter how roundabout.

To ensure that networks do not interfere with each other, nodes are dedicated to only one network and traffic is encrypted to secure it from outside traffic.

Most battery-operated devices, however, will not function as signal repeaters. Those that do so have to be permanently on the lookout for idling commands, thus shortening their battery lifetime.

The microchip

They say good things come in small packages, and that’s certainly true of Z-Wave. The entire Z-wave protocol is contained in a single microchip that is small enough to fit on your fingertip. Currently used in more than 200 products, the Z-Wave chip is a powerful, highly integrated, mixed-signal platform that enables your devices to be controlled and monitored wirelessly.

It contains six main blocks:

  • A radio frequency transceiver
  • A microprocessor
  • 32kb flash memory, containing the protocol and application
  • Digital and analog system interfaces to connect to devices
  • An authentication 3DES system, which ensures confidentiality and security of your signals
  • A Triac dimming controller, which eliminates the need for separate dimmers, as everything is already on the chip

Two-way routing

Routing is an essential element in Z-Wave’s sophisticated wireless system. Through two-way RF routes, commands reach their destination by routing or passing signals from one node to another. This has the effect of extending the operational range to 45 meters (150 feet) indoors, and over 150 meters (500 feet) outdoors.

The robust and reliable wireless protocol provides full home and yard coverage through routing commands that work their way around sources of interference or radio dead spots, like walls, metals, fridges and other obstacles in your home.

Low bandwidth – high powered

Z-Wave uses Frequency-shift keying (FSK) modulation schemes, which is the technology used in cordless phones. It operates around 900 MHz, which is an ideal band for residential control applications.

This bandwidth is more than sufficient to send and receive the few bytes used in small messages, such as those required to switch devices on and off, dim lights and gather data from sensors. Because the amount of data communicated on these waves is small, reaction time is very fast, running at 9600 bits per second.

Network assignment

To use a network of Z-Wave devices, you need one primary controller, and one controllable device set up in its final position. Most users start with a portable controller, like the Intermatic HA07 and the Leviton RZCPG.
By entering a key sequence into the controller and pressing a button on the device, you can add the latter to the network. This standardized serial protocol process will have to be repeated until the controller is eventually paired with all the devices.

After initial installation, these devices keep their addresses within the network and remain connected full-time and operational unless in sleep mode. It is possible to bridge two or more networks, though this is not usually necessary in a small and controlled residential environment.

Z-Wave manufacturers, Zensys, have literally redefined the notion of home automation through their well-knit wireless mesh network, but the system does have its drawbacks. Visit our pros and cons (link: 23_Z-Wave pros and cons) page to learn more about the system.

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