Siemens SINAMICS S120 Function Manual page 906

Communication
11.8 Time synchronization between the control and converter
If the snap has not been transferred within 5 s after receiving the ping, then this
synchronization cycle is not used.
Figure 11-53 Ping snap
Differences for isochronous and non-isochronous communication:
Communication
Isochronous
not isochronous
Time synchronization via Network Time Protocol (NTP)
Through NTP, all computers worldwide can synchronize their time. An inverter configured as
an NTP client synchronizes the time via a PROFINET connection to an NTP server (a time
source).
As NTP server, the following constellations are possible:
● Local NTP server that receives the time via GPS or DCF77 (e.g. SICLOCK).
● Control as NTP server if the plant network is divided into a control level and a field level.
906
Description
The ping compensation value is determined in the converter.
You can influence the accuracy of the ping compensation using the PZD
sampling time (p2048).
Function Manual, 11/2017, 6SL3097-4AB00-0BP5
Drive functions