Home automation is a vast subject, with many types of protocols and configurations. KNX is one of them, KNX, origin of the word is Konnex from Latin dictionary means connection. And is the globally standardized wire line system for the residential & non residential building automation, and have successfully replaced the 75% of predecessor market. It has replaced EIB (European International Bus), EHS (European Home System) & Baitbus which was use mainly in France.
Being stable wire system, KNX have become the first globally recognized standard systems, and is wide used in home automation, approved by various standards as below
| United States of America | ANSI / ASHRAE 135 |
| European Union | EN 500900 |
| China | GB / T 20965 |
| International | ISO / IEC 14543 – 3 |
| CEN | EN 13321 – 1 |
It is hardware independent standard, and all the KNX products from any manufacturer can be operate with one another without failure. All the devices & data protocols are compliant with the KNX standards hence upward & downward compatibility is possible thereby making same as future proof. Hence KNX devices are inter-operable and Networkable. As the devices are capable to be connected with all the components in the network, the transparency as well as utilization of information across the network is possible. The availability for single cable bus for the integration for different systems helps in designing the seamless solution for home automation and other applications.
Communication Medias
The physical communication Medias as per this standard are Twisted pair wiring, Power line networking, Radio (KNX-RF), Infrared, Ethernet as used in home automation.
The main components for KNX are Sensors, Actuators and components generally referred as SAC . Sensors gather the information about the subject & object, and transmit same as data telegrams. While as actuators receive these data telegrams for action. And the components included application for connectivity on the bus. The topologies supported are tree, line & star while as ring topology is not permitted.
KNX logical topology in figures is as below
| Devices on fully distributed line | 65,536 |
| Address space | 16 bit |
| Devices/ Line | 256 |
| Total lines | 15 |
| Line coupler | 1 |
| Segments per line | 4 |
| Devices per segment | 64 |
| Segment Length | 1000 Meters |
| Connections with segments | 4 |
| Length in total for 256 Devices | 4000 Meters |
The twisted pair transmission using this standard are mathematically as below
| Signaling speed | 9600 bit/sec |
| Wave resistance | 120 Ohms at 100 KHz |
| Line resistance | Min: 20 Ω/km, Max 75 Ω/km. |
| Maximum capacitance | bus-to-bus line max 800 pF/m at 800 Hz. |
| Network nodes | 57600 |
| MAC control length | 1000 Meters |
| Total segments | 4 |
| Maximum length | 4000 Meters |
Models of communication
The modes of configuration are A, E & S means Automatic, Easy & System mode respectively. In Automatic mode devices are generally plug & play, in Easy mode little knowledge is require while-as in System mode high expertise is needed for design and installation.
It is widely used in building & home automation like Lighting, Blinds & Shutters, Security Systems, Energy Management, HVAC Systems, Monitoring Systems, Remote Control, Metering, Audio& Video systems etc.
KNX Association administers the KNX standards worldwide
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