4 Installation Kübler Group
14 - EN HB Profibus Interface - R67068.0002 - 01
4.1.4 Termination
If a device is the last participant on the bus, the looped-through PROFIBUS must be terminated
actively at both ends with a bus termination resistor between A and B. For closed devices, the
termination must be specified in the order or provided by means of en external resistor. For
good signal transmission, PROFIBUS segments must be terminated with a bus termination. For
PROFIBUS RS485, the bus termination consists of three resistors.
The bus termination can be activated in the device or is prepared in the switch. If more than 32
participants are connected to the bus, repeaters must be used to connect the single bus seg-
ments. The terminating resistors between the lines are generally 220 Ω. 390 Ω resistors are
used between the reference potentials. Generally, the line termination is located in the cables or
in the respective PROFIBUS device, but it can also be installed separately. Network Topology
[}15]
Cable termination
Every bus segment must be terminated at both ends with a termination resistor. This cable ter-
mination is integrated in the RS485 repeaters, in the bus terminals and in the bus connectors,
and it can, if necessary, be activated. The component must be powered before the cable termin-
ation can be activated. The RS485 repeaters and the termination have their own power supply.
The RS485 transmission technology allows connecting at the maximum 32 devices per bus
segment (DTE's and Repeaters).
The maximum permissible cable length depends on the transmission speed and on the used
LAN cable. Network Topology [}15]
4.1.4.1 Termination with Sendix 58xx
The bus termination is set via hardware with the two DIP switches on the bus cover of the en-
coder rear side.
Both switches on: Termination active
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