An important part of Automation Technology:The KNX Standard

Since the 1990’s, the automation of processes has already become an essential part of research for industrial communication. After all, where complex installations and heavy machinery are used, it is advantageous to allow the components of a system communicate with each other, so that the comfort of the work and its efficiency are increased by the independence of the network participants, and also more safety can be offered by a separate and joint diagnosis. For this reason, fieldbus systems are being designed with the focus on finding an internationally recognized standard, so that the technology is freely accessible by manufacturers and users.

The Definition of KNX

KNX stands for an open bus system that is used in the sector of flexible electrical installations and has developed into a standard. This fieldbus system was developed for the housing and construction sector, on one hand to increase the comfort and the safety of the inhabitants, and on the other hand to increase the economy of the building by lower costs and higher efficiency. Within a network, the KNX standard takes care of connection of the electrical installations with the devices, so that the work steps can be automated and sources of error can be eliminated.

The Structure of the KNX Standard

Basically, the design of the KNX standard contains two essential structures, the physical structure (1) & the logical structure (2)

  1. As in every conventional network operating with buses, the line is also the smallest unit on the KNX standard. Up to 64 participants can be coupled to one such line. This number is already decided in advance by the voltage supply, as each individual segment requires its own supply with the KNX standard. However, when a network with an essentially larger scope is required, up to 15 additional lines are added singly, although all of these are connected with the central main line via a line coupler. Devices like sensors and actuators, which control the most important functions in the system, are found as a rule on this main line. The main lines can also be connected via a link, in this case a backbone coupler, so that the complete bus technology can also be used for large buildings, as the max. number of participants in the end is at 61455 buses. Each individual one is identified by a physical address, where the couplers within this network topology always receive the participant number 0.

  2. The logical structure is considered to be freely programmable. here, the actuators and sensors that should communicate with each other are connected via a group address. Because of this structure, changes in the network can be made without the need to lay new lines. The interaction between the participants then takes place via regulated and specified commands, thus ensuring that the KNX standard is actually open and freely accessible in regard to the devices of manufacturers and the users.

The employed technology with the KNX Standard

Within the open fieldbus system, the actuator acts as control unit between the mains voltage and the consumer. Data that can be sent directly via the sensor or indirectly comes from the computer and occurs in the form of telegrams which are sent to the control unit via the coupling of the actuator to the network topology. Once the control receives a command from a sensor, the mains voltage is connected to the device. The entire network of the KNX standard is supplied via a constant 30 V rated voltage, which also supplies the bus couplers with the required voltage.

The Advantages of using the KNX Standard

The specifications of this open fieldbus network has existed since 2002. This standard, developed for the automation of houses and other buildings, now has many advantages, with the result that it has become an important part of information technology and industrial communication.

  • Any type of electrical consumer can be operated.
  • Simple and quick operation of the devices.
  • New connections can be defined by new programming, with the result that the tasks of a device can be changed from one location to another.
  • Different sensor data can be called by a system.
  • Flexibility
  • Uniform network
  • Thanks to communication with each other, devices can react independently to influences.

A Conclusion for the KNX Standard

Worldwide, KNX is still the only standard in the housing and construction sector, which is internationally recognized and openly accessible. By meeting the requirements of the standards CEN 50090 and CEN 13321-1, as well as the standard DIN ISO/IEC 14543-3, the KNX standard grew from a simple fieldbus system to a technical application with specifications that can also be used in the heating, venrilation and air conditioning sector, which led to a monopoly position within building automation. The only disadvantage of the KNX standard is that is actually not open, as its use first requires entry into the respective organization, which expects a contribution from its members.