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Error-free configuration of the MPI/DP interface and the I/O
How do you test the I/O using the S7-PLCSIM simulation program?
The I/O is configured automatically with CPU modules without DP connection (e.g. CPU314). When you plug a module into a PLC, then that module is recognized automatically by the CPU. This configuration cannot be simulated with a simulated automation system. If you load a program from an S7-300 CPU (which configures the I/O automatically) into S7-PLCSIM, the system data does not include an I/O configuration.
In practice, automatically configured S7-300 CPUs (CPUs without DP connection) behave in S7-PLCSIM in the same way as loading program blocks without system data. Also when programming non-existent I/O addresses the CPU does not go into the STOP state. The I/O is handled as if that arbitrary address were available.
All S7-300 CPUs with DP connection (like the CPU 315-2DP, for example) and all S7-400 CPUs handle the I/O in S7-PLCSIM as it is in reality. More information on this topic is also available in the Online Help for S7-PLCSIM under:
The following table explains how you can use S7-PLCSIM to test the I/O without any errors.
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