Communication; Interfaces; Multi-Point Interface (Mpi) - Siemens CPU 31 Series Technical Data Manual

Communication

3.1

Interfaces

3.1
3.1.1

Multi-Point Interface (MPI)

Availability
All the CPUs described here are equipped with an MPI interface
A CPU equipped with an MPI/DP interface is configured and supplied as
MPI interface. 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 on an MPI subnet.
The typical (default) transmission rate of all CPUs is 187.5 kbps. You can also set 19.2 kbps
for communication with an S7-200. Baud rates of up to 12 Mbaud are possible with the
CPU 315-2 PN/DP, CPU 317 and CPU 319-3 PN/DP.
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.
CPU 31xC and CPU 31x, Technical Data
Manual, 01/2006 Edition, A5E00105475-06
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