Configuring   
4.11 Planning subnets 
  S7-300, CPU 31xC and CPU 31x: Installation 
4-30  Operating Instructions, Edition 08/2004, A5E00105492-05 
4.11.2  Configuring MPI and PROFIBUS subnets 
4.11.2.1  Overview 
The next section contains all the information you require to configure MPI, PtP and 
PROFIBUS subnets: 
Contents 
•  MPI, PtP and PROFIBUS subnets 
•  Multi-Point Interface 
•  PROFIBUS DP 
•  MPI and PROFIBUS network components 
•  Example of networks - MPI 
4.11.2.2  Basic principles of MPI and PROFIBUS subnets 
Convention: device = node 
All devices you interconnect on the MPI or PROFIBUS network are referred to as nodes. 
Segment 
A segment is a bus line between two terminating resistors. A segment may contain up to 32 
nodes. It is also limited with respect to the permitted line length, which is determined by the 
transmission rate. 
Transmission rate 
Maximum transmission rates: 
•  MPI: 
–  CPU 315-2 PN/DP and CPU 317: 12 Mbps 
–  All other CPUs: 187.5 kbps 
•  PROFIBUS DP: 12 Mbps