Siemens SINUMERIK 840D sl Equipment Manual page 72

Connecting
7.9 PROFIBUS DP
The following list provides examples of when using MPI (multi-point interface) may prove
effective:
• If a PC/PG with an MPI is being used
• If an MPI-type handheld unit is being used
Operate MPI like PROFIBUS
The information on wiring the connector (terminating resistors) for PROFIBUS and the rules on
the laying of cables for PROFIBUS apply to this interface as well. When carrying out this
procedure, consult the relevant references.
Connector features
The bus connector is used to connect the MPI bus cable to the MPI (X136). This enables you to
establish connections to additional nodes (e.g. PG or SIMATIC S7-CPU). Only bus connectors
with a 35° cable outlet should be used in order to ensure that the front cover can be closed.
MPI bus cable
The PROFIBUS cable specifications apply here as well. Please note the relevant information on
setting up an MPI network.
Setting up an MPI network
Keep in mind the following basic rules when setting up an MPI network:
• When using the interface as an MPI interface, it is not possible to arrange additional control
for a drive in isochronous mode or to connect distributed I/Os to this interface.
• An MPI bus line must be terminated at both ends. This is achieved by activating the
terminating resistor in the MPI connector in the first and last station and deactivating the
other terminating resistors.
• At least one terminator must be supplied with 5 V.
This means that an MPI connector with an activated terminating resistor must be connected
to a device that is switched on.
• Spur lines (cables leading from the bus segment to the node) should be as short as possible,
i.e. < 5 m in length. Unused spur lines should be removed wherever possible.
• Every MPI station must be connected to the bus first and then activated.
To disconnect the station, it must first be deactivated. Then, the station can be removed from
the bus.
• Maximum cable lengths:
– 200 m per bus segment
– 2000 m total length with RS 485 repeaters
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Equipment Manual, 10/2020, 6FC5397-1EP40-6BA1
NCU 7x0.3B PN