One of the advantages of choosing the Z-Wave Home Automation standard is the wide variety of modules available from the many manufactures that support it.
The Z-Wave wireless protocol is one of todays most widely adopted home automation technologies. It delivers a reliable and easy to install network suitable for almost any smart home. One of its great benefits is that it’s supported by more than 160 vendors who’ve introduced over 700 Z-Wave-based devices. This means that whatever type of device you’re looking for, there will be a Z-Wave version available. Furthermore, each of these devices is tested and certified by the Z-Wave Alliance, so compatibility is assured.
However, this doesn’t mean that all Z-Wave devices will work with each other. This article looks at issues users need to be aware of and how they affect device compatibility.
Z-Wave Backward Compatibility
Interoperability is at the centre of Z-Wave. All newly certified devices are backward compatible with existing Z-Wave products. This means today’s latest devices work with products from the earliest days of Z-Wave.
However, forward compatibility is a different matter. It’s not possible for a device released today, to support future device types or Z-Wave commands. You can’t support things that haven’t been defined or developed yet.
For instance, a remote control released in 2007 will control lights (On/Off/Dim); it is fully certified and works well. During 2010, new command classes were introduced allowing LED colours to be controlled as well as their brightness. Our remote control from 2007 can still control the new LED devices, but it can’t control their colour. This could be considered incompatibility, but this wouldn’t be fair, as these commands weren’t even invented when it was introduced. However, it does mean that a user needs to be careful when choosing a controller for devices that incorporate new command classes.
Certification vs Full Command Class Support
When a device is certified, it doesn’t have to support all Z-Wave command classes, it only needs to support the command classes for its intended function. It will be fully certified so long as these classes are correctly supported. This makes sense for devices such as actuators where they only need to support the relevant command classes for controlling lamps and appliances attached to them.
Problems arise when Z-Wave controllers don’t support all command classes. For example some controllers don’t support the classes used for locks and other security devices. There is nothing wrong in a controller not supporting particular classes, so long as this is documented to ensure customers know which device types can be used with it. Sometimes this information isn’t freely available in vendor’s documentation, so users usually need to dig a little deeper.
Also, it’s worth noting that controllers regularly receive firmware updates where new device and class support are added; so if a particular class of device isn’t supported now, it probably will be in the near future.
It’s not just Z-Wave controllers that have regular firmware updates, some more complex devices such as multiple sensors or even wall plugs can have firmware updates. So it’s always worthwhile checking if a new device has the latest firmware before trying to install it. If you’re not sure, check with your reseller, the best ones will be able to tell you what the firmware is and how to update it.
There is a huge variation in Z-Wave documentation quality and consistency. The ZWave Alliance enforces common language for critical functions such as Include, Exclude, Association etc., but vendors can use their own terminology for other functions and processes. This can be confusing to the user as different vendors may describe the same process in different ways. This is made worse as most documentation is also translated from the vendor’s local language. Device documentation is now often supplemented by tutorials and videos showing how to install and use the devices.
Old Devices – Old Classes
As Z-Wave has matured over the last 10-years, its certification processes have become more strict and controlled. Through this time, some devices have gained certification that wouldn’t receive it today; these devices are now rare but will have incompatibilities with other devices. In many cases these devices had support for early implementations of Z-Wave classes, or classes that quickly became
superseded. For instance the ‘Multi Instance’ class was deprecated in favour of the ‘Multi Channel’ command class.
For most users, this won’t be an issue unless you’re trying to use a very old device.
Choosing the Right Devices
There has never been such a wide choice of Z-Wave devices and the level of compatibility and interoperability has never been higher. But users still need to be careful when selecting devices to work in their system.
For this reason, Vesternet created and maintains the only Z-Wave Compatibility guide. This helps users choose the devices that work well together and with a variety of Z-Wave controllers. And, to make it even easier, all verified products carry the ‘Vesternet Certified’ badge, taking all the guesswork out of choosing the right devices. Vesternet also has a huge library of tutorials, videos and resources that make it easy for people to install and use the devices.