Installation manual

Networking
5-4
S7-400 and M7-400 Programmable Controllers Hardware and Installation
A5E00069481-04
Number of Nodes
MPI PROFIBUS DP
127 127 *
(default: 32) of which: 1 master (reserved)
1 PG port (reserved) 1 PG port (reserved)
125 slaves or other masters
* Observe the CPU-related maximum numbers in the Reference Manual CPU Data,
Chapter 4
MPI/PROFIBUS-DP Addresses
In order for all nodes to be able to communicate with one another, you must assign
them an address:
• In the MPI network, an MPI address
• A PROFIBUS-DP address in the PROFIBUS-DP network
Default MPI Addresses
The following table shows the default MPI address and the max. MPI address with
which the devices are shipped:
Node (Device) Default MPI Address Default Highest MPI
Address
Programming device 0 32
OP 1 32
CPU 2 32
Note
If you change the parameter assignment of the highest MPI address of the MPI/DP
interface, the new address remains set even after memory reset, voltage failure or
removing/inserting the CPU.
Rules for MPI Addresses
Observe the following rules before assigning MPI addresses:
• All MPI addresses in an MPI network must be different.
• The highest possible MPI address must be  the highest actual MPI address
and must be set to the same value for all nodes. (Exception: connecting a
programming device to two or more nodes.)