Siemens SIMATIC S5 Manual page 6

1 Introduction
Description of the automation task
One of the standard communication structures for systems is the star topology. A
head-end station (PC or SIMATIC head-end station) communicates with several
substations. These substations, however, also communicate with each other via
cross-communication.
In SIMATIC S5 systems, the communication of a control center/S5 head-end
station to its substations is often implemented by means of the FETCH/WRITE
service (level 7 communication). Cross-communication between S5 substations is
done via the SEND/RECEIVE service (level 4 communication).
In the course of a partial migration, a SIMATIC S5 station is replaced by a
SIMATIC S7-1500 station.
The example projects/scenarios in this document show the options available to
establish a communication via Industrial Ethernet between the existing
SIMATIC S5 controllers and the SIMATIC S7-1500 via the available protocols and
services.
Ethernet Communication (ISO on TCP) between SIMATIC S5 and
SIMATIC S7-1500 Controllers
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