Functional description

System expansion

Based on a bus terminal block consisting of a Bus Coupler and a maximum of 64 Bus Terminals, using the K-bus Extension Terminals KL9020 and KL9050 your system can be expanded by up to 31 terminal blocks. The expansion terminal blocks can be equipped with a maximum of 64 Bus Terminals each. The maximum permissible configuration consists of 255 Bus Terminals and 1020 I/Os. The K-bus Extension Terminals KL9020 and KL9050 enable a distance of 5 m max. between two terminal blocks and therefore an overall system length of 155 m.

Functional description 1:
KL9020 and KL9050 in the Beckhoff Bus Terminal system

The K-bus Extension Terminals KL9020 and KL9050 integrate seamlessly into the Beckhoff Bus Terminal system in terms of their appearance and functionality. The transparent terminal lugs used for labelling indicate their function as system terminals.


The End Terminal with RJ45 socket (KL9020) is plugged into the end of the bus terminal block instead of a standard End Terminal (KL9010) and enables the connection of the K-bus extension cable. The electronics of the KL9020 are supplied via the K-bus from the Fieldbus Coupler.


In the expansion terminal blocks, the Coupler Terminal KL9050 replaces the Fieldbus Coupler and takes over its function. It is mounted on the mounting rail at the start of the extension station and connected to the preceding Bus Terminal block via an RJ45 socket with the designation IN by means of a K-bus extension cable with a maximum length of 5 m. Connect the K-bus extension cable

The power contacts and the corresponding connection points of the Coupler Terminal are electrically isolated from the K-bus.

K-bus extension cable

The data is transmitted between the terminal blocks via eight-core Ethernet cables with RJ45 plugs. Beckhoff offers pre-assembled cables in different lengths, which can be customized with commercially available Ethernet tools.

Functional description 2:

The K-bus Extension Terminals should also work with cables from other manufacturers. However, Beckhoff recommends the use of Beckhoff Ethernet cables, which are tested for the specified functionality.