Configuring
4.11 Planning subnets
S7-300, CPU 31xC and CPU 31x: Installation
Operating Instructions, Edition 08/2004, A5E00105492-05
4-33
Equipotential bonding
For information on what to take into account with respect to equipotential bonding in your
network configuration, refer to the corresponding chapter in the appendix.
Reference
For further information, refer to the Communication section in
CPU 31xC and CPU 31x
Manual, Technical Data
.
4.11.2.3 Multi-Point Interface (MPI)
Availability
All CPUs described in this manual are equipped with an MPI interface X1.
A CPU equipped with an MPI/DP interface is configured and supplied as MPI. To use the DP
interface, set DP interface mode in STEP 7.
Properties
The MPI (Multi-Point Interface) represents the CPU interface for PG/OP connections, or for
communication in an MPI subnet.
The typical (default) transmission rate for all CPUs is 187.5 kbps. You can also set 19.2 kbps
for communication with an S7-200. The 315-2 PN/DP and 317 CPUs support transmission
rates up to 12 Mbps.
The CPU automatically broadcasts its bus configuration via the MPI interface (the
transmission rate, for example). A PG, for example, can thus receive the correct parameters
and automatically connect to a MPI subnet.
Note
You may only connect PGs to an MPI subnet which is in RUN.
Other stations (for example, OP, TP, ...) should not be connected to the MPI subnet while
the system is in RUN. Otherwise, transferred data might be corrupted as a result of
interference, or global data packages may be lost.
Devices capable of MPI communication
• PG/PC
• OP/TP
• S7-300 / S7-400 with MPI
• S7-200 (19.2 kbps only)
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