Siemens S7-300 appendix Interfaces, Multi-Point Interface MPI, Availability, Properties

Communication 3

3.1Interfaces

3.1.1Multi-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 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. 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 interference, or global data packages may be lost.

CPU 31xC and CPU 31x, Technical data	3-1
Manual, Edition 08/2004, A5E00105475-05