Technical data

PROFIBUS Network Manual
System Manual, Edition 04/2009, C79000-G8976-C124-03
41
Network configuration
3
3.1 Configuring electrical networks
3.1.1 Overview
PROFIBUS networks
PROFIBUS networks were specially designed for use in an industrial environment and one
of their main features is their degree of immunity to electromagnetic interference resulting in
high data integrity. To achieve this degree of immunity, certain guidelines must be adhered
to when configuring electrical networks.
Parameter
The following parameters must be taken into account when planning an electrical network:
● The transmission speed required for the task (within a network, only one uniform
transmission speed can be used)
● The required number of nodes
● The type of network components required (bus terminals, bus connectors, connecting
cables)
● The bus cables to be used
● The required segment lengths
● The electromagnetic and mechanical environment of the cabling (for example surge
voltage protection, cable trays)
● The number of RS485 repeaters between any two end devices is limited to a maximum of
9
● Increasing the overall span of a network by using several repeaters can lead to longer
transmission times that may need to be taken into account when configuring the network,
see section
Frame transmission time (Page 58).
Terminator
All segments must be terminated at both ends regardless of the transmission speed. For this
purpose, the cable terminator made up of a combination of resistors must be activated in the
relevant connection elements. There must be no further cable sections after an activated
terminator.