Siemens SIMATIC S7-1200 CP 1243-8 IRC Operating Instructions Manual page 26

Application and functions
1.9 Configuration examples
Inter-station communication between stations
Inter-station communication is possible for stations connected to the same master station.
For the inter-station communication between stations, the master station forwards the
messages of the sending station to the receiving station.
Telecontrol communication - Ethernet
In the sample configuration shown, an S7-300 and two S7-1200 stations communicate with a
master station SINAUT ST7cc/ST7sc.
The CPs are connected via their Ethernet interface.
The connection to the Ethernet network, in this example a fiber-optic cable, is implemented
using SCALANCE X switches. Copper cable is also possible as the medium.
Figure 1-2
26
Communication via an Ethernet network (optical medium)
Operating Instructions, 02/2018, C79000-G8976-C385-03
CP 1243-8 IRC