FAQ: Z-Wave Public Specification

Z-Wave is a wireless communication standard designed to allow smart home devices of all types and brands to “talk” and work together. It is the world’s most widely-deployed smart home technology, and found inside products such as lights, door locks, security systems, climate controls, window blinds and much more, connecting them together in functional and intuitive ways. Z-Wave is found inside more than 50 million products, comprising 70% of the smart home market. It is already the wireless protocol of choice for more than 375 global smart home device manufacturers, IoT platform suppliers, and all types of service providers.

Middleware and application developers: The public availability of the Z-Wave standard protocols will give developers of middleware and smart home automation the ability to interact more directly with Z-Wave devices, using the established and maintained Z-Wave standard and not having to rely on 3rd party translation application interfaces. This allows for user interfaces that build on the standardized Z-Wave interoperable devices, and give end users unparalleled quality of choice.

Gateway manufacturers: They can now expose the Z-Wave standard interface in their gateways to utilize 3rd party middleware without having to implement a custom translation application interface.

IoT Interoperability Initiatives: They will now be able to develop plugins for connections through services, and others that can work directly with Z-Wave products and gateways. This will help tie the smart home into cloud initiatives and popular cloud services, which in turn will extend the reach of smart home products and Z-Wave’s overall leadership position.

The Z-Wave Community: Non-commercial implementation by hobbyists, enthusiasts and students will now be possible through the ability to access the world’s leading smart home language.

Four years ago, the entire specification for Z-Wave radios was adopted by the ITU, an International Standards body. That was the first step in opening Z-Wave, and enabling any silicon manufacturer to develop and produce Z-Wave chips.

We have always maintained that it we would open up the Z-Wave interoperability layer when the timing was right. Through our thirteen years of working with hundreds of blue-chip device manufacturers, we have created THE gold standard for IoT Smart home device profiles, as well as command and control capabilities.

Our competitors recently started following in our footsteps, and have started to create their own profiles, and therefore there is no reticence on our part to expose our remarkable portfolio to the world. Further, with the explosion of cloud applications and development for the IoT, this initiative allows Z-Wave to become the standard smart home language for developers of every stripe.  Cloud services need an IP-friendly language that can speak to gateways, and through this initiative, Z-Wave will extend its position as the language of choice.

The Z-Wave Alliance has always been adamant about ensuring that when a consumer buys a Z-Wave branded product, it will always work together with the other Z-Wave branded products they already have at home – regardless of which manufacturer, retailer, or service provider from whom these devices were bought or manufactured.

Unfortunately some other alliances are ignoring this important end-consumer need, and misleadingly use the word “interoperability”, even when it is only on a more basic networking level that the devices can connect. The data they then exchange may still be proprietary to the individual manufacturer. So even though two devices can join the same network, there’s absolutely nothing the end-customer can use them for, as one manufacturer’s device cannot control devices from another manufacturer.

When the Z-Wave Alliance Partners talk about interoperability, what we mean is that devices can understand one another, not only join and exchange undefined data on the simple networking level.

The Z-Wave Command Class Specification, which describes the 600+ standardized messages currently defined in Z-Wave. This is the “language” that Z-Wave devices speak. The various Command Classes define how commands and information are carried to, from, and between devices; for example, the command for switching a light bulb on, or how to request the energy metering data from the last 10 minutes that has been gathered by an electrical socket.

The Z-Wave Device and Role Types Specifications, which describes the different types of devices that can be part of a Z-Wave network, and the different types of network behavior these devices may adopt. It also standardizes the way in which these devices announce their primary purpose, and other capabilities to the rest of the network. In combination, the Device and the Role Type specifications help to ensure devices in the network know how, when and what to communicate, as well as what to expect from other devices in the network.

Together with the Command Class specification, this provides the rock-solid foundation on top of which Z-Wave interoperability is built.

Since many Z-Wave networks today also are being controlled remotely via smart phones, cloud services, IoT platforms and the like, we are also opening up the specification for how to send Z-Wave commands via IP, as well as a major update to the security mechanisms that can be used with Z-Wave.

These parts of the Z-Wave Interoperability Specification include:

 The Z-Wave over IP Specification, which describes the standard for transporting Z-Wave messages over IP networks. This also includes a reference implementation called Z/IP Gateway, and the complete API specification for how to build an application on-top.

One such application, Z-Ware, developed by Sigma Designs, will also be available, and as the name suggests it is a complete Z-Wave middleware, and will be available with the API description for how to build a customer facing User Interface on-top.

The Security S2 Specification, which describe the comprehensive and robust framework used by Z-Wave to secure messages in a Z-Wave network. Z-Wave’s Security S2 is by far the most secure framework in the IoT industry today. By releasing the specification into the public domain, Sigma Designs invites additional security experts to scrutinize and challenge the security mechanisms used in Z-Wave.

The Z-Wave over IP, or “Z/IP” Specification describes how Z-Wave commands may be encapsulated and transported securely over IP based networks. The Z/IP Gateway software is a fully mature software implementation of how these IP packages then get unpacked and passed on as normal Z-Wave wireless communications through a small bridge or gateway that resides within the home. The bridge can either be a low cost, stand alone device, or it can be the home owner’s existing broadband router, which then just runs the Z/IP Gateway software.

On a more technical level, Z/IP carries Z-Wave messages inside UDP packets. These messages are directly addressed to a Z-Wave device’s IP address. These IP addresses are being provided as proxy IP addresses by the Z/IP Gateway implementation, and the gateway also serves the important role of physically bridging between the IP side (typically Ethernet, Wi-Fi, 3G or 4G, Fiber, etc.) and the sub-GHz wireless Z-Wave communication.

This allows companies to use standard Z-Wave for the in-home wireless communication, but to essentially make every device IP addressable from the internet/cloud side via the Z/IP Gateway implementation. Often referred to as “mesh-under”, this method offers a way to connect in-home devices to the Internet in a way that is both far more cost and energy efficient than having to deal with the overhead of using IP technology for short-range in-home wireless communication, while at the same time leveraging the more than 50 million Z-Wave devices, spread over more than 1500 different Z-Wave and Z-Wave Plus certified devices, that are already in use today.

Z-Wave Plus, introduced in 2013, is a marketing certification program designed to help consumers identify products that take advantage of the Z-Wave Platform 500 series. It is a selected set of extended features and capabilities that make Z-Wave installations even simpler to perform. Z-Wave Plus products are backward-compatible with Z-Wave. Our goal is to drive a best in class security and interoperability for all Z-Wave users.

Well, it is, and it has been so for a while, in the sense that it was open to anyone who was interested in developing a Z-Wave product and purchased the development tools needed for this. What we are doing now is to also give the general public access to the specification, so that academia, analysts, hobbyists, other IoT interoperability groups, and the like can read, use and comment on how Z-Wave works, without having to join the Z-Wave Alliance or buy a development kit.

How Z-Wave devices physically send data wirelessly to each other is already in the public domain, since it is based on an ITU specification called G.9959. This specifies the PHY and MAC layer Z-Wave is based on, i.e. the frequencies used in different parts of the world, as well as the modulation and encoding schemes used, how to access and share the RF medium and bandwidth with other devices, etc. This is analogous to the IEEE specification called 802.15.4 which defines alternative PHY and MAC layers that groups such as the ZigBee standards setting committee have based all of their numerous standards on, and which the Thread group more recently also chose.

What devices then say to each other when they communicate, is defined in the Z-Wave Interoperability Specifications that the Alliance is now opening up to the public.

There have also been open source communities that have worked with Z-Wave for many years. OpenHAB, also known as the Eclipse Foundation’s Smart Home project, and OpenZ-Wave, are probably the most well known of these. There has even been an initiative that built a software-defined radio based on the ITU specification, and has provided these open source groups with additional tools to listen to and reverse engineer Z-Wave communication between devices. This is only possible if the manufacturer did not utilize the security features of the protocols, which, needles to say, all access devices such as door locks and garage door openers are required to do, but which simple temperature sensors and light switches were not previously required to do.

Sigma Designs, who provides the development kits for Z-Wave, always signs mutual non-disclosure agreements with our customers. Until now, this made it difficult for the company and for other Z-Wave Alliance members to support these open source initiatives. Releasing source code, where e.g. the Z-Wave Command Classes could be read in clear text, essentially was a violation of the confidentiality agreements.

To further accelerate the tremendous global adoption of Z-Wave, we would however like to better support these important and innovative developer communities and allow them to bring their implementations to a level where they can pass the comprehensive Z-Wave Interoperability Certification. We believe the Z/IP Gateway implementation is the right base from which to offer this support. By offering these communities Z/IP upon which to base their open source projects, as well as by releasing the APIs and Command Class Specifications, we can support and even encourage these initiatives, while the IoT market continues to explode.

The Z-Wave Alliance continues to be the steward of the Z-Wave brand and regulates the interoperability between all Z-Wave devices that carry the logos.

There are plenty of other technologies that allow devices to wirelessly talk together, but Z-Wave is unique in also specifying what these devices then say to each other, and defining the meaning of these commands. The Z-Wave Alliance provides the necessary role of mandating that all members stick to this specification, and to provide a strong product certification program to support it. The Z-Wave Alliance continues to define and ensure enforcement of the high level of interoperability that is the hallmark of Z-Wave.

It’s important to note that the Z-Wave Alliance is a not-for-profit organization, which is  funded by membership fees, particularly from the growing number of Promoter level members. It is not funded by the certification fees, which cover labor costs and operating expenses, and are paid directly to the independent test-houses the Alliance has authorised to conduct the interoperability testing.

The Alliance members have also been instrumental in developing the Z-Wave Command Class “language” over the years, both by adding additional detail and in broadening the scope, and it will continue to do so going forward. With publicizing the very latest Command Class and Device and Role Type specifications, the Alliance encourages comments and suggestions to the spec, but in order to participate in the actual working groups and to vote on new command classes or enhancements of existing ones, companies or individuals still need to join the Z-Wave Alliance as Full Members.

On the B2B side, the Alliance also serves as a strong community for collaborating on creating and expanding business opportunities. A Smart Home Cloud Service provider may have an opportunity to license their solution to an energy utility company, but needs to find a partner that makes Z-Wave thermostats, so their utility customer can use their cloud service for demand response programs. Or a Smart Plug manufacturer may be working with a telco company that already developed a Smart Home service in-house, but to make the overall offering more compelling to consumers, they may need to find a gateway hardware provider that offers a more competitive platform than the one the telco used during the pilots and trials. The Z-Wave Alliance serves as a forum for these companies to find likeminded business partners and complementary products.

Only if they wish to be commercially available and use the Z-Wave logo.

Sigma Designs will initially release for download the Z/IP Gateway and Z-Ware software to run on the Raspberry Pi platform, which has the largest developer community in the world. With Raspberry Pi, a Z-Wave USB stick, and the Z-Wave Interoperability Specification, you’re ready to start creating Z/IP applications or to make your own User Interfaces on-top of the Z-Ware middleware.

In addition, we expect many of the Z-Wave Alliance partners that provide Z-Wave gateways to also port Z/IP to run on the application processors they chose for their hardware configurations.

And lastly, anyone wishing to run the Z/IP software on a platform not covered by the above, can get the source code for the Z/IP implementation simply by buying a Controller Development Kit from any of the official Z-Wave distributors.

With the publication of the Z-Wave standards, Sigma Designs is leading the way to improve machine-to-machine (M2M) communication in the growing world of IoT. Simply connecting different device types is not enough — they need to understand the communication and take full advantage of a device’s capabilities. The collaborative development of Z-Wave Command Classes over more than a decade, combined with the competitive pressure of working in an Alliance alongside your competitors, has meant that the Z-Wave language has evolved to facilitate an incredible richness in end-product features.

By making the Z-Wave Interoperability Specification available also to these “device abstraction” initiatives, we want to make sure that all these fantastic little product features and opportunities for manufacturers to differentiate their products — while still maintaining interoperability even with their competitors –doesn’t get “lost in translation”. As an example, for something as simple as a light, we want to ensure that features such dim-rates, delayed on/off, returning to previous level instead of full-on, etc., doesn’t get abstracted away to a simple “Light On” command, thereby leaving the homeowner incapable of using the full set of features available in the products bought, or and adjusting it to individual preferences, simply because a different App was chosen to control it than the one the manufacturer supplied.

Yes they can, as long as they take it through the certification process to guarantee the quality of the communication.

Yes, this is possible, but if you want to use the Z-Wave logos and word marks, you will need to certify your products. Certification will assure that no implementation errors were made in your products, so that consumers can rely upon them working as they should in terms of Z-Wave interoperability.

The interoperability layers will be evolving over time. This evolution will continue to be governed by the Z-Wave Alliance and as such, requires a membership of the Z-Wave Alliance. If you “only” want to use the interoperability layers, you do not need to be a member of the Z-Wave Alliance.

There is a forum that is being created, and will be released around the middle of September 2016.

Yes. Registration for future updates is optional.

Yes, anybody that can access Sigma Designs’ web site can download it

Release of the S2 specification will educate the entire market on how our security is working. The days of security by obscurity are over. Modern consumer-grade hardware can easily crack, de-compile, or sniff encryption keys. Z-Wave S2 security does not rely on a secret implementation to make up the security. Being open about how it works allows security experts to properly assess the level of security implemented in Z-Wave. We see it as an invitation for others to comment on and perhaps make Z-Wave security even stronger over time.

Yes, if they go through the Z-Wave certification process, which results in approval to use the logo on the product.

The Z-Wave certification program has two components: technical certification managed through Sigma Designs and a third party test house; and a marketing certification program managed through the Z-Wave Alliance, which approves the logo use on the product and packaging once the product has an official Z-Wave technical certification number.