When talking about smart home solutions, it is inevitable to hear about Zigbee, but many current and future owners of smart home systems ask themselves, what is Zigbee?

Read on to find out more about the Zigbee communication protocol, the need for a special bridge or gateway and the resulting advantages and disadvantages.

Please note that we will not go into detail about the steps for setting up the network in this blog post; you can find the detailed steps here.

ZigBee is a standardized and versatile wireless protocol for smart buildings. It covers the control of various types of devices and can also be controlled via the Internet of Things (IoT), provided a corresponding Zigbee control center is available. Controlling light is just one of many types of devices.

The Zigbee protocol was designed to transmit small amounts of data, minimize radio traffic and minimize energy consumption. The low energy consumption enables operating devices that can be operated with a 3V battery in the long term or that can even generate the required power themselves at the moment the switch is operated.

Thanks to its easy installation, ZigBee is ideal for users who do not want to deal intensively with the technology. Nevertheless, it is possible to build complex and customized home automation systems with it.

The Zigbee protocol was originally developed by the Zigbee Alliance, a cooperation of well-known manufacturers such as Philips, Osram, Amazon, Ikea and Bosch, to name but a few. Today, the Zigbee protocol is being further developed by the  csa, connectivity standards alliance, alongside other IoT-related activities.

Zigbee uses the same frequencies in the free 2.4 GHz band as Bluetooth and WiFi. Thanks to the special digital coding, the systems generally do not get in each other's way. However, heavy data transfer in WiFi, such as downloading movies, can affect the response speed in the Zigbee network.

Similar to a WLAN, a Zigbee network consists of at least one control center and one device that is to be controlled. All devices in this network communicate wirelessly with each other. The control center controls the communication and, like the WLAN router, assigns each device a unique network ID after registration. Only with this ID and other security information can a device participate fully in the network.

It is easily possible to set up separate networks side by side with several Zigbee control centers. These then work alongside each other without interfering with each other. For example, two apartments in the same house can each operate their own Zigbee network independently of each other.

Data transmission between the devices included in the network and with the Zigbee control center is encrypted and tap-proof. However, as with all digital communication, security depends on the software on the devices. Naturally, there are loopholes. Such networks have already been compromised under laboratory conditions.

The same cat and mouse game is taking place with Zigbee as with the computer infrastructure: gaps are identified and the manufacturers close them with the next update.

If Zigbee is mainly used within the building for the smart home, the risks are manageable. They are definitely not as explosive as banking transactions on your own computer or smartphone.

Various devices are integrated into the network from a Zigbee control center (technical term: coordinator). Examples of Zigbee control centers are Philips Hue, Amazon Echo Plus or Homee. The Zigbee control centers are usually connected to the router via LAN so that access to the Internet is possible. This is required for software updates and optional remote access. Configuration and control is usually possible via an app.

The app can only communicate with the coordinator if a WLAN is available. This is required in addition to a LAN. The LAN must then be available at all locations in the building. 

The illustration shows different types of devices that are supported in a Zigbee network. The illustration is not complete and focuses on common applications in a smart home.

It is also common for manufacturers to limit the functionality of their coordinators.

For example, Philips Hue currently only supports light control and switchable sockets. Amazon Echo and Homee offer a wider range of device types.

With the iluminize shutter actuator, we adapt the light control and translate the switching and dimming into commands for the motors in up and down. This makes it possible to integrate roller shutters or screens even with control panels that only support light control.

The structure of a Zigbee network shown schematically

There are two basic device types in the Zigbee network: actuators and sensors.

Actuators execute commands from the Zigbee control center and, for example, switch the light or move a roller shutter. They are usually supplied with an external and permanent voltage.

Sensors tell the control panel (or the actuators) what to do. Sensors such as a remote control or a wall switch often feed their energy from batteries or generate it themselves. They are therefore limited and only send signals to the Zigbee network when they are operated. 

In contrast to the actuators, which are always accepted by a Zigbee control center, the manufacturers unfortunately severely restrict the sensors. Often only the controls from their own production or those from partners are displayed in a reasonable and configurable way. This is partly due to the complexity of the sensors with their many functions, but unfortunately it is often simply a matter of economic calculation.

With the new Zigbee standard version 3.0, the so-called Touchlink was included in the protocol. This means that, for the first time, remote controls and wall switches can be connected to individual devices directly and without central configuration on the coordinator, regardless of the manufacturer's wishes. Both devices, the sensor and the actuator, must support the procedure.

This is possible with the iluminize remote controls and wall switches/dimmers. The process is described in the instruction manual and in the article:  "How do I set up my Zigbee network"

The range of the radio signals is limited. In the best case, a range of up to 30 meters is possible. However, metals, stone and concrete used in the building hinder signal propagation, meaning that the range is considerably shorter in practice. In unfavorable cases, the devices on the upper floor cannot be reached from the control panel.

To improve reception and range, all actuators that receive a signal from the network retransmit it. They thus become a router that serves as a signal amplifier. The process is already familiar from WLAN. Theoretically, the signal chain can be as long as you like. In practice, with clever positioning of actuators in the building, even the last corners and the upper floor can be easily reached.

Simplified representation of a Zigbee mesh network

As they generally do not have a stable power supply, the sensors are not part of the mesh network. They are therefore not part of the signal forwarding (mesh), but can use it. See blue arrows in the image for examples of signal paths.

Note: If a device is to be connected to the coordinator for the first time, this cannot be done via the mesh network. The new device is not yet a known Zigbee participant at this point and its signals are ignored. Always carry out the initial connection (also known as pairing) near the control center.

Due to the convenience of operation in the browser or via app, we at iluminize always recommend the use of a Zigbee central unit. The choice depends on the objective to be achieved. If "only" the light and possibly some sockets and shutters are to be controlled smartly, a Philips Hue Bridge may be the most cost-effective and simplest solution. If the entire building is to be smart, other control centers must be used.

For small projects, consisting of a pair of sensors and actuators per room, there is the option of operation without an external Zigbee control center. Our iluminize actuators and controllers take on the function of a coordinator in such systems.

The configuration, which is described in detail in the instruction manual and the article:  "How do I set up my Zigbee network", is then carried out without a convenient app but only via a few buttons and signals by the multiple flashing of LEDs. Extensive systems are difficult to implement in this way, although it would be possible.

We only recommend this procedure for larger systems in an emergency, for example if the system is to be mobile and no WLAN is available, or for pairs of actuators and sensors.

Want to start building your own smart home with Zigbee? Follow these simple steps to make the right decisions. We are also happy to help you personally. We will be happy to answer your questions at our helpdesk (for simple questions) or in a free, no-obligation and detailed telephone call. Please schedule  an appointment in our calendar.

As shown above, a Zigbee control center for the entire building is a sensible and long-term investment. The costs for this vary between around €50 for a Philips Hue Bridge and several hundred euros for a control center that can handle complete home automation including heating and weather. Complete and sometimes free Zigbee systems are available based on computers, Raspberry PI and Zigbee USB sticks. Many systems can also be integrated into voice control systems from Apple, Google and Amazon. The market is very broad and new providers appear every day. A comprehensive list of all the possibilities is beyond the scope of this article.

If you only want to control lights, sockets and shutters/screens, the Philips Hue Bridge, also in combination with voice control, is the ideal solution. It is cost-effective, sophisticated and very easy to configure and operate.

The Zigbee control center is the basis for every Zigbee network and every further step depends on the selection. It should therefore be made at the beginning and depends on your wishes today and in the future. Follow the table.

Decision criteria for a suitable Zigbee control center

A decisive factor in a complex Zigbee network is the subsequent operation in the individual rooms. You also need to think about central functions such as "central on/off" on the door, "children's room off", "coming and going" via GPS on the smartphone at an early stage.

Jeder Hersteller hat in seiner Zigbee-Zentrale verschiedene Möglichkeiten zur Steuerung implementiert und es steht ein Sortiment möglicher Bedienungen mit direkter Einbindung und Konfigurationsmöglichkeit in der App zur Verfügung. Wie schon dargestellt, interagieren die Bediengeräte der Hersteller nicht immer untereinander. Die Entscheidung für eine Zigbee-Zentrale bedeutet so auch immer eine Entscheidung für eine Auswahl von Bediengeräten.

Ist Philips Hue eine optimale Wahl für dich, empfehlen wir den Einsatz von "Friends of Hue" Schaltern. Diese sind für einige Schalterhersteller verfügbar: Busch Jäger, Gira (Scenic) und Jung. Diese Schalter lassen sich in Philips Hue (aber auch andere Zentralen) einfach einbinden und später frei konfigurieren. In der Regel benötigen diese keinen Stromanschluss und keine Batterien. Sie erzeugen sich beim Drücken den Strom selbst.

Mit den vorhandenen Druckpunkten, die wie Taster funktionieren, lassen sich frei Lampen, Räumen oder Zonen zuordnen. Innerhalb dieser Zone schaltest du per Druck eine Szene an, welche alle Lampen und Leuchten deines Raums in eine vorher gespeicherte Stimmung  fährt. Diese Szenen bekommen einen Namen, beispielsweise "Fernsehen", "Essen", "Kochen" oder "Zentral aus". Ein Klick und dein Raum hat das perfekte Licht für "Fernsehen" oder "Essen". Es lassen sich so bis zu 4 Szenen oder 3 Szenen und Raum zentral auf einem solchen Schalter abspeichern.

Die Bedienung ist für jedermann möglich, auch kleinen Kindern oder Senioren, und leicht verständlich. Oben links bedeutet "Fernsehen", oben rechts bedeutet "Essen" und unten links bedeutet Raum komplett ausschalten.

Andere Schalter und Fernbedienungen sind auch möglich und werden beispielsweise benötigt, wenn Farben dynamisch ohne die Nutzung der App eingestellt werden sollen. Das können die vorgenannten Schalter nicht.

Beispiele für "Friends-of-Hue" Wandschalter

Nicht jede Lampe lässt sich gut in eine Zigbee-Steuerung einbinden. Kaufst du deine Lampen ausschließlich nach Geschmacks- und Designaspekten, kann das später ärgerlich oder teuer werden, wenn diese nicht oder nur zu hohen Kosten unter Zigbee funktioniert.

Wir bieten zahlreiche Zigbee-Vorschaltgeräte an, aber die Erfahrung der letzten Jahre zeigte uns, dass für viele Leuchten keine Lösung existiert. Achte bitte insbesondere auf die folgenden Restriktionen.

230V Leuchten die sich per Phasenschnitt dimmen lassen

Beim Phasenschnitt (Phasen-AN-Schnitt oder Phasen-AB-Schnitt) wird die 230V Versorgungsspannung gleichzeitig zum dimmen genutzt. Das Verfahren stammt ursprünglich aus der Zeit der Glühlampen, welche über einen Glühdraht verfügten. Bei diesen Lampen ist es kein Problem, wenn die Sinuswelle an- oder abgeschnitten wird. Sie leuchten einfach nicht so hell, wenn gedimmt wird.

LED-Lampen haben jedoch eine aktive Elektronik, welche die Spannung reduziert und für die LED umwandelt. Diese Elektronik, oft Treiber genannt, kann durch den Phasenschnitt beeinflusst werden. Oft sind solche Leuchten, die über einen weniger hochwertigen Treiber verfügen, nur bis 40%-50% der maximalen Helligkeit dimmbar. Danach stellt sich ein Flimmer- oder Flackereffekt ein.

Es gibt jedoch auch Lampen und leuchten, die perfekt funktionieren und sich bis 0% flimmerfrei dimmen lassen. Im Zweifelsfall solltest du die Leuchte zusammen mit einem Zigbee-Treiber für Phasenschnitt testen. Mit unseren Zigbee Dimm- und Schaltaktoren lassen sich, unter Beachtung der obigen Restriktionen, viele mit 230V betriebene Lampen und Leuchten in ein Zigbeesystem integrieren

Leuchten mit Konstantstrom

Eine LED funktioniert grundsätzlich mit konstantem Strom. Die Spannung ist der LED dabei unwichtig. Die effizienteste Art eine LED zu betreiben, ist also die Versorgung mit einem geeigneten, konstanten Strom. Jeder LED-Typ hat aber einen individuellen, optimalen Strom bei dem das Verhältnis zwischen Wärme, Lebensdauer und Helligkeit optimal ist. Der Treiber, welcher der Lampe meistens beiliegt, wird deshalb auf der Primärseite mit 230V versorgt und es gelten die Restriktionen aus dem vorstehenden Abschnitt. Sekundärseitig liefert der Treiber den für die LED optimalen Strom in einem Spannungsbereich. Beispiel: 5W LED bei 700mA. Die Spannung liegt dann für eine einzelne LED bei etwa 7,15V.

Soll der mitgelieferte Treiber jedoch durch einen direkt Zigbee-fähigen Treiber ohne die oben genannten Restriktionen ersetzt werden, muss dieser Treiber 700mA im Spannungsbereich um 7V liefern. Werden drei LED in Reihe betrieben, sind es immer noch 700mA, jedoch muss die Spannung des Treiber 3 x 7.15V = ca. 21-22V betragen. Ein solcher Treiber ist bei uns verfügbar. Es könnte aber auch sein, dass die Lampe 96mA bei 156V benötigt. Dafür ist am Markt definitiv kein Zigbee-Treiber erhältlich.

Es ist also wichtig, dass du zuvor prüfst, ob 1. der 230V Treiber ausreichend dimmbar ist und wenn nein, 2. den Strom/Spannungsbereich zu ermitteln und einen passenden Zigbee-Treiber im Vorfeld zu suchen. 

Hersteller wechseln oft ohne Ankündigung ihre LED und damit den Strom-/Spannungsbereich. Gerade bei den aktuell problematischen Lieferketten muss oft auf Ersatzprodukte ausgewichen werden. Die Angaben sollten deshalb besser vor Typenschild des Treibers und nicht aus dem Katalog entnommen werden.