Siemens Simantic Net NCM for Industrial Ethernet S7 - Manual (Page 40)

Communication via Ethernet CPs in S7 Stations
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SIMATIC NET NCM S7 for Industrial Ethernet
C79000-G8976-C129–06
Representative Objects for Stations Outside the Current Project
If you do not want to use the multiproject functions, you can fall back on the use of
representative objects as used previously.
To be able to network the representative objects, you must once again create a
subnet of the type PROFIBUS in both projects as shown in the example here.