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Assembly and Installation Instructions
6
Shielding and routing bus cables
6.7
Shielding and routing bus cables
6.8
Bus termination
32
The PROFIBUS interface supports RS-485 transmission technology and requires the
cable type A to IEC 61158 as the physical medium for the PROFIBUS. This cable must
be a shielded, twisted-pair cable.
Correct shielding of the bus cable attenuates electrical interference that may occur in
industrial environments. Take the following measures to optimally shield bus cables:
•
Manually tighten the mounting screws on the connectors, modules, and equipotential
bonding conductors.
•
Use only connectors with a metal housing or a metallized housing.
•
Connect the shielding in the connector over a wide surface area.
•
Apply the shielding of the bus line on both ends.
•
Route signal and bus cables in separate cable ducts. Do not route them parallel to
power cables (motor leads).
•
Use metallic, grounded cable racks in industrial environments.
•
Route the signal cable and the corresponding equipotential bonding close to each
other using the shortest possible route.
•
Avoid using plug connectors to extend bus cables.
•
Route the bus cables closely along existing grounding surfaces.
In case of fluctuations in the ground potential, a compensating current may flow via the
bilaterally connected shield that is also connected to the protective earth (PE). Make
sure you supply adequate equipotential bonding according in accordance with relevant
VDE regulations in such a case.
The DFS11B option is not provided with bus terminating resistors. This enables the bus
system to be put into operation more easily and reduces the number of error sources.
Use a connector with integrated bus terminating resistor if the DFS11B is located at the
beginning or end of a PROFIBUS segment and only one PROFIBUS cable leads to the
DFS11B option.
Switch on the bus terminating resistors for this PROFIBUS connector.
Manual – Fieldbus Interface DFS11B PROFIBUS DP-V1 with PROFIsafe
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