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ABB i-bus
®
KNX
Planning and application
4.1.2
KNX telegrams in the network
Note
When designing the KNX system it is important to note that the number of transferred telegrams is also
limited when the IP Router Secure is used. Due to the high baud rate on the IP side (10/100 Mbit/s),
telegrams may be lost with high levels of data exchange on the TP1 line (9.6 kbit/s) for system reasons.
Multicast
Multicast designates communication of a transmitter with a group of receivers. The IP Router Secure
sends the KNX telegrams packaged as UPD/IP telegrams on the IP network, and all IP Router Secure
devices parameterized with the same multicast address receive and evaluate these telegrams. If a
telegram is intended for the corresponding subline, the IP Router Secure routes the telegram into the line.
Otherwise, it is rejected.
The IP Router Secure sends telegrams from the KNX to the IP network in accordance with the KNXnet/IP
protocol specification. These telegrams are sent in the default setting as multicast telegrams to the
multicast IP address 224.0.23.12 port 3671. This multicast IP address is the defined address for the
KNXnet/IP from the KNX Association in conjunction with IANA for KNX IP devices. This address should be
retained. It should be changed only if the existing network demands that another address be used.
In order for several IP Router Secure devices to communicate with one another in a network, multicast
communication must be possible between the devices. Depending on the type of network and the setting
of the network components used, e.g. routers, switches or firewalls, the multicast IP address 224.0.23.12
may need to be enabled explicitly beforehand. Please discuss the topic with your network administrator.
For further information, see chapter 3.2.3,
Unicast
Unicast generally refers to communication between a transmitter and a receiver. In other words, the
Router sets up a communication connection to every IP Router within the unicast group.
If multicast communication is not possible in a network, the ABB IP Routers can also communicate with
each other via unicast. Up to ten ABB IP Routers can be combined to form a unicast group. The unicast
group can consist of IPR/S 3.1.1 and/or IPR/S 3.5.1 or a mix. Each Router is then assigned nine IP
addresses to which it sends its telegrams.
Automatic configuration of this unicast group is simple with the ABB i-bus
It is also possible to link a client (e.g. a visual display system) with this unicast group. In this case, one of
the ten unicast addresses is used by the client and up to nine IP Router Secure devices can be linked.
The exact description of how configuration with the i-bus
Tool (see chapter 4.2,
Note
As soon as the parameter is changed to Unicast under Type of IP communication in the ETS, the
function Multicast is deactivated. The devices can then no longer be programmed via multicast routing;
they can be programmed only via one of the integrated tunneling servers or a separate programming
interface.
However, the type of communication will be changed only when parameterization with the i-bus
has taken place. Until then, the Router will remain internally set to multicast. This offers the advantage
of programming the Router via multicast.
For more information, see parameter window
36 2CDC502099D0211 Rev. A | IPR/S 3.5.1
Parameter window IP
The i-bus®
Tool).
IP
settings.
settings.
®
Tool.
Tool works can be found in the help of the i-bus
®
®
Tool
®
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