In this article, we want to explore some common mistakes we see people make when setting up their Z-Wave networks, and the simple steps you can take to avoid them in your setup.
When data is sent from one Z-Wave node to another, this is called a hop. Despite all the benefits of mesh networking, too many hops can cause significant transmission delays and can choke the network with excessive traffic. You will always get the best reliability and performance when your controller is capable of reaching a good proportion of the network directly. The simplest way of achieving this is to physically position your hub in the most central location in your home, relative to the other nodes on the network.
By simply moving the controller closer to the centre of the network resulted in this configuration:
Bonus tip: To make controller placement easier, most hubs will feature a Wi-Fi bridging option to allow connecting the controller to your local network wirelessly. This is ideal in situations where a wired ethernet point is not available at your target location. Check for this setting under your controller's network configuration.
More is More
For a Z-Wave Plus network, it's usually recommended to have at least one powered Z-Wave device roughly every 20 meters for maximum efficiency, but in our experience, reducing this to 10 meters is preferred. If it's not possible to add additional nodes at a particular location due to wiring constraints etc, consider using a dedicated Z-Wave range extender or a simple Z-Wave wall plug which can achieve the same outcome.
Distance between nodes is not always the main criteria for adding more. Z-Wave radio signals may reflect off walls, furniture and other obstacles and cause two nodes that are just a few meters apart to be completely invisible to one another. By adding more powered devices and/or repeaters in the mesh avoids Z-Wave “dead zones” due to these reflections.
The Proper way to Pair
After all your the mains powered nodes have been added, this is the right time to add all your battery operated devices.
Bonus tip: Unless it's absolutely crucial to your setup, we'd recommend not using secure inclusion. This is an option set on the controller when pairing which ensures all traffic between the controller and the device is encrypted. Secure Inclusion adds considerable overhead on the Z-Wave network so it should be used sparingly. It is strongly advised to only use it for devices that really need this extra level of protection. A door lock would be one such example.
Polling is the Enemy
Z-Wave is a low-bandwidth network protocol and is not designed to be highly utilised. Polling is considered bad practice because it can quickly flood your network with polling traffic, resulting in slow transmission times and failures. Unfortunately, polling is still enabled by default in some controllers so please check your system settings to confirm it is off. If you really have to poll a device, make sure you increase the polling interval to the maximum time possible for your application.
Bonus tip: While you're poking around under the hood, make sure your devices are not broadcasting too often as well. For example, we sometimes see power metering (on devices which support this) cranked to crazy levels which can generate frequent updates back to the controller. Do a quick check of any per-device Z-Wave configurations that might cause this kind of unnecessary traffic.
Understanding Network Healing
Network healing is a feature built into most Z-Wave controllers and it forces a re-discovery of neighbouring nodes. The controller can self-heal the network to an extent - automatically searching for alternative routes when required - but it may take a while before a better route is discovered. Fortunately, a heal can be performed on demand and can be done at a network-wide level or at a node level. The feature is sometimes referred to as a network repair but regardless of the name, the underlying task performed is the same. You will usually find the option in your controller's Z-Wave configuration settings.
Healing your network is highly recommended whenever a new device is removed without following the proper Z-Wave exclusion process, or, when a device is physically relocated to a different part of the house. Every time you add a new node to an existing network, it is good practice to heal at least a few surrounding nodes as well.
And there you have it! We've covered a lot of ground but hopefully this info helps set you on a path of mesh networking bliss. As always, feel free to drop us a note if you need any further details on anything discussed here.