Profibus / Mpi; Connection Components In Profibus; Profibus Cables And Connectors - Siemens SINUMERIK 840D sl Manual

Connections

9.7 PROFIBUS / MPI

9.7 PROFIBUS / MPI
9.7.1

Connection components in PROFIBUS

Connection components
Individual nodes are connected by means of bus connectors and PROFIBUS cables.
Remember to provide a bus connector with a programming port at either end of the subnet.
This will give you the option of expanding the subnet if required, for example, for a
programming device.
Use RS 485 repeaters to connect segments or extend cable lengths.
Segments
A segment is a bus line between two terminating resistors. A segment may contain up to
32 nodes. In addition, a segment is limited by the permissible cable length, which varies
according to the transmission rate.
Terminating resistor
A cable must be terminated with its own surge impedance to prevent line disturbances
caused by reflections. Activate the terminating resistor at the first and last node on a subnet
or segment. The control unit must be either the first or the last node on the subnet.
Make sure that the stations to which the terminating resistor is connected are always
supplied with voltage during power-up and operation.
9.7.2

PROFIBUS cables and connectors

Properties of PROFIBUS cables
The PROFIBUS cable is a two-stranded, twisted, and shielded cable with the following
features:
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Manual, 07/2007, 6FC5397-0AP10-2BA0
NCU