KNX/EIBnet IP.

KNX/EIBnet IP.

In home and building electronic systems the KNX/EIB bus as well as IP networks are some of

the most important standards for the future. The definition of the EIBnet/IP standard was a

major step in the integration of both protocols into one system.

In the standard solution, an IP network connects several KNX/IP gateways to access the KNX

subsystems, enabling communication between different KNX lines via the IP backbone. But

all senders and receivers of KNX telegrams are still connected to the KNX media.

Today many devices have an Ethernet connection but cannot be controlled via KNX. To integrate

such a device into the KNX world it would not make sense to add an additional hardware

interface to the KNX/EIB bus. It would be much more convenient to establish the KNX

communication via the IP link, providing a KNX device without a connection to the KNX

medium. It may be called a virtual KNX/EIB device.

what about the configuration of such a device?

To obtain full integration into the

KNX/EIB world, the device should be programmed using the ETS software, permitting the

setting of group addresses and parameters in a closed environment.

Today many buildings are equipped with an IP network which is used mostly as a network for

personal computers. On the other hand IP networks are increasingly able to serve automation

systems. So it is obvious that this technology is an interesting solution especially for building

automation. Existing systems like the KNX/EIB bus can be linked to an IP network for use as

a fast backbone.

          

Figure 1 shows an installation with two KNX/EIB lines connected via the IP network. To link

a KNX/EIB line to the IP network a KNX/IP-Router is needed. It converts the KNX/EIB telegrams

into IP frames and vice-versa according the EIBnet/IP standard. Besides, it filters the

telegrams to keep the bus load low. An EIBnet/IP client can access any KNX subsystem via

the IP network. Due to the routing capabilities of the EIBnet/IP servers, direct exchange of the

telegrams between two servers is possible.

        

Figure 2: Virtual KNX/EIB device

Figure 2 shows the theme of this paper: We replace one line consisting of the EIBnet/IP gateway

and one KNX end device with a single component, obtaining a new device which may be

called a KNX/EIB device for IP media. The former KNX/EIB device is now only present as

a virtual device. It is visible in the complete network as a standard KNX/EIB device although

it has no conventional connection to the KNX/EIB bus.

Instead it is linked to the KNX/EIB network via the Ethernet connection and the EIBnet/IP

features of the device. When programming the virtual KNX/EIB device using the ETS, the IP

network is invisible.

Software

This chapter describes the software architecture for KNX/EIB devices for IP media. It consists

mainly of an UDP/IP stack, which handles the communication between the network and

the virtual KNX/EIB device.

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