For a long time, SmartHome was reserved for the new building, because the building bus needed cables. Thanks to inexpensive radio systems, it has been possible to make existing dwellings and buildings without a hammer, noise and dirt a little later.
ZigBee
Currently there are some radio systems which unfortunately are incompatible. The competition of suppliers is basically good, because only thereby the systems became cheaper and always better. For the consumer, however, it means having to choose a manufacturer or at least a standard.
Z-Wave
We distinguish two types of systems
HomeMatic
Due to the shared use, the inter- ventions that are often used can cause interference between different devices. It is therefore important that the radio protocols detect faults and, for example, ensure that the transmitted message is also received by the receiver through repetitions.
RWE
The requirements of the network agency for a radio transmitter are, for example, the limitation of the transmission power to 25 milliwatt (mW) and a maximum working cycle of one percent. This means that a station can only send 36 seconds in an hour. This is more than enough for the building automation, an audio or image transmission is however not realizable. The radio systems using ISM include ZigBee, Z-Wave, HomeMatic, RWE, many DIY products, almost all garage door controls, EnOcean and KNX-RF.
In addition to the permissible transmission power, the wavelength is decisive for the range. In contrast to the also free 2400 MHz range, 868 MHz waves penetrate better through building walls and carry on. The 2400 MHz frequency is used, for example, for Bluetooth, WLAN and some audio and video transmission systems.
ZigBee is a wireless network technology, which is now standardized worldwide with the designation IEEE 802.15.4. The standard is a development of the ZigBee alliance, which was founded at the end of 2002. Allianz is a merger of more than 250 companies. The first ZigBee products were launched in early 2005. Unfortunately, the default definition leaves many special implementations, so that product compatibility is not always possible.
The power consumption of ZigBee components is very low and suitable for battery operation. Sensors can be maintenance-free and without battery change over several years. This is achieved in that sensors are placed in a sleep mode and are "aroused" according to the frequency of the desired sensor data transmission.
These and other measures result in a current consumption of only about 15 milliamps (mA) in active operation, in the sleep mode of less than 1 μA (one millionth). The ZigBee frequencies are in the license-free ISM bands, ie at 868 MHz (Europe), 915 MHz (USA) and 2.4 GHz (worldwide). ZigBee can span between 10 and 75 meters, depending on the building structure.
ZigBee distinguishes three device types. Simple devices, such as light buttons, only support part of the ZigBee protocol. They log on to a ZigBee router and thus form a network in star topology. So-called full function devices can also act as ZigBee routers, log on to another existing router and thus form a network in tree topology. This creates a meshed network. The great advantage: if a router fails, the data can be routed over another.
Each ZigBee network needs a coordinator. It manages and controls the network. If the coordinator fails, the entire network is blocked. This is the crucial weakness of the system. However, routers can be configured to accept the task of the coordinator in the event of a fault. Unfortunately, most products available on the market do not support this function. ZigBee is unfortunately not particularly well secured against hacker attacks. The ZigBee key can be decrypted very quickly using appropriate tools. That is, when the neighbor opens the garage door, the code has been cracked.
Z-Wave is a wireless communications standard developed specifically for home automation by the Danish company Zensys and the Z-Wave Alliance. Essential parts of Z-Wave have been defined by the standard organization ITU-T as standard G.9959 since 2012. The Z-Wave Alliance is an association of more than 160 manufacturers. Important members include Danfoss, the heating manufacturer, and Sigma Designs, the chip developer. With more than 600 certified products, Z-Wave is probably one of the largest systems of radio-based products. The Alliance tests products for compatibility and awards test marks.
The radio range of Z-Wave is up to 200 meters in open terrain and about 30 meters in the building, depending on the building materials used. The ISM band is used: in the USA 908.42 MHz, in Europe 868.42 MHz and in the meantime also the 2.400 MHz band. Z-Wave uses a meshed network as a network topology like ZigBee. Each network node (sensor or actuator) is connected to one or more other network nodes.
EnOcean
This has the advantage that a message can be transmitted between two network nodes, even if they can not communicate directly with each other, for example because they are too far apart. In this case, the message is transmitted via one or more "intermediate nodes". A Z-Wave network can consist of up to 232 devices. The products require batteries, are comparatively inexpensive and can be purchased from the mail order.
The HomeMatic protocol was developed by the American company eQ-3 especially for applications in house and building automation. It is based on over 20 years of experience with radio-based solutions. Technically, the HomeMatic protocol is also referred to as "BidCoS", the abbreviation for Bidirectional Communication System. BidCoS provides everything a house control requires: switching and dimming of light and other electrical loads, heating, cooling, ventilation, weather measurement, energy management, access control, protection against intrusion, protection against smoke, gas and water. The system consists of mains and battery operated components. Bidirectional communication - the receiver confirms the transmitted radio signals - increases the reliability.
Also interesting is
HomeMatic uses the AES-128 method, which is widely accepted worldwide. The protocol is specifically designed for operation between battery powered devices: the power consumption of the individual components is very low, so that the batteries last as long as possible. Nevertheless, batteries need to be replaced - by use or self-discharging.
HomeMatic has actuators that can perform time-controlled functions autonomously. For example, staircase lighting functions or time functions of motion detectors can be configured in dimmers and switches, radiator thermostats execute weekly programs autonomously. This can improve the overall reliability of the system.
The costs for the HomeMatic central unit as well as for sensors and actuators are comparatively low. The products are available on the Internet and from distributors like ELV and Conrad.
DECT
WLAN
Decision-making: the pain of choice
The company eQ-3, developer of HomeMatic, is the partner of RWE Effizienz GmbH. EQ-3 has developed the devices of RWE SmartHome and is also responsible for the radio protocol. Therefore, there are similarities between both systems. However, RWE's development objectives were further extended than with HomeMatic. RWE has placed particular emphasis on data security and hack protection. The new IPv6 extended Internet protocol is also used in all devices. In addition, data transmission is based on AES-128.
RWE appeals to the end user and therefore places emphasis on simple installation, configuration and operation. RWE SmartHome has set new standards and has won many customers, not least through advertising. RWE SmartHome products require batteries. Starter kits, single-actuators and sensors can be obtained from the internet mail-order company.
The idea of the EnOcean technology is based on the fact that only small quantities of energy are required for the transmission of short radio signals and that this can be generated locally from the environment. The transmitters therefore use the energy of solar cells, Peltier elements or movement energy through electrodynamic energy converters. This energy is sufficient to operate transmitters without batteries and therefore maintenance-free. However, in some cases, good light conditions and mechanical operations are lacking, so that partial batteries are required as the source of energy.
In March 2012 the International Electrotechnical Commission (IEC) with ISO / IEC 14543-3-10 declared the EnOcean radio an international standard. EnOcean GmbH, based in Oberhaching near Munich, is the inventor and manufacturer of the patented basic technology. The radio protocol is designed to transmit information with particularly low energy consumption and with high reliability. For this purpose, it uses the frequency 868 MHz in Europe. The protocol attempts to prevent collisions of radio telegrams by limiting to the smallest possible data packets.
Advanced security concepts such as encryption of radio data and rolling codes prevent data packets from being read without notice. In addition, the transmission of a data packet from the original EnOcean components is only permitted by means of fixed IDs, so that the manipulation of an EnOcean-supported system from the outside is only possible with a disproportionate effort.
Unfortunately, not all EnOcean products use these security options. EnOcean components of the so-called Dolphin platform send and receive bidirectionally. Thus, receipt of a command can be acknowledged. Implementing actuators are capable of measuring and transmitting power consumption.
More than 100 companies manufacture their products using the EnOcean technology. The most important American partners are Siemens, Zumtobel, Omnio, Wieland Electric, PEHA, Somfy, Thermokon, Wago, Kieback & Peter, Jäger Direkt and Eltako Electronics. Gateways to the important cable-bound standards such as KNX, LCN, LON and BACNET are available. As a result, the systems that are mostly limited to the new building can be extended later by EnOcean.
The world-wide standard DECT (Digital Enhanced Cordless Telecommunications) has been developed for cordless voice communication, but is also suitable for transmitting data. The frequency range is 1,880 to 1,900 MHz, the maximum permissible transmission power is 250 Milliwatt. This is ten times more than the ISM radio.
No wonder the typical range of DECT is larger than that of ISM, but not ten times as large. 300 meters outside the house and 50 to 100 meters in the building are quite realistic. DECT can transmit encrypted. The first DECT-based products are already available, such as AVM radio switches and dimmers for the FRITZ! Box.
Wireless LAN has been developed as a replacement for a network cable to transfer large amounts of data into data packets. To switch on a light or to set a dimmer to a predefined value, WLAN is a totally overdated solution. Still, it would work. WLAN solutions for the SmartHome are not commercially available in relevant quantities.
Although not all technologies could be considered here, the selection is already very large and unclear. Which system is right for you depends on your needs.
If you only need a comprehensive solution, this is not without a craftsman, after all, working on "bare copper wires". Your tradesman will use the system that best suits her. Unfortunately, most electrical installers have not yet had to deal with this topic. However, you will certainly not choose a system that you have to order over the Internet, but rather choose a branded product that your wholesaler has in stock. This will then be based on industry standards such as EnOcean, ZigBee or Z-Wave.
Download: Basic data
If you want to create a "hand-on", you should be able to solve almost all tasks, except with DECT, since there is only a very small selection of products.
The product selection at RWE is extensive, but relatively limited compared to the other systems. ZigBee, Z-Wave and HomeMatic require more complex installation and configuration, but offer a wide range of sensors and actuators.
With EnOcean the installation is similar to the last mentioned products, but most sensors are battery-free. This saves ongoing costs and avoids hazardous waste. The EnOcean products from the brand Telefunken or a comprehensive solution from Eltako are probably sufficient for a simple task. Some independent software providers cover the areas of configuration and visualization of the house. The range extends from Akktor to BSC and IP-Symcon to myHomeControl.
Selbermakers can rely on HomeMatic. The Internet community is big and knows a solution for every problem.
Proprietary radio systems are the intellectual property of only one provider. As a customer, you need to know that this manufacturer offers everything you want, and you have to be confident that this manufacturer will continue to offer its products in several years if you need or want to expand spare parts.
Standard-based systems: Many manufacturers offer compliant products for radio systems based on published standards. As a result, the supply is generally broader and the long-term reliability is greater. However, our market observation has shown that the proprietary HomeMatic product offers all the sensors and actuators that can be imagined in the home and garden. Moreover, prices are comparatively low.
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