Entry type: FAQ, Entry ID: 23847972, Entry date: 08/30/2006

What are the options for exchanging data between CPUs via MPI/PROFIBUS DP?

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SIMATIC S7 provides diverse communication services and connections.
Here we present a selection of options for data exchange between CPUs (S7-300, S7-400). The select does not include all conceivable possibilities.
Usually the MPI/PROFIBUS DP interface is used for CPU-CPU communication.
Please also note the different data and consistency areas in the individual CPUs and services.

1. MPI interface and communication services

Communication services Further information and notes
Global data SFC manual 1) Chapter 19;
FAQ 430498 with detailed instructions.
S7 basic communication with X_PUT, X_GET SFC manual, sections 22.5 and 22.6
1) SFC manual is used in the FAQ as an abbreviation for the manual "System Software for S7-300/400 System and Standard Functions" that is available in Entry ID: 1214574 .

An overview of the communication options via MPI is available in Entry ID: 21537047. A detailed explanation is available in the SFC manual, chapters 19 - 22.

2. PROFIBUS DP interface and communication services

Type of connection Further information and notes
Master/Master DP-DP coupler links two networks;
manual in Entry ID: 1179382
  CPUs connected via CP 342-5;
application in Entry ID: 20987807
Master/Slave S7 basic communication with X_PUT, X_GET:
SFC manual, sections 22.8 and 22.9; application in Entry ID: 20987910
Master and slave must be in the same project, one CPU is I slave.
Slave/Slave (internode communication) FAQ with Entry ID: 1016961

Further information and notes

  • A systematic overview of all communication with SIMATIC S7 is available in Entry ID: 20982954 and in the manual "Communication with SIMATIC" in Entry ID: 1254686.
  • Additional communication services are available in the SFB manual in the chapters on communication.
  • Connection between S7-300/400 and S7-200 is described in the FAQ in Entry ID: 747743 .