Siemens SIMATIC S7-1500 System Manual page 221

Commissioning
11.9 Time synchronization
Time-of-day synchronization with the user program
Time-of-day synchronization can be implemented through a user program.
Example:
SIMATIC S7-1200/S7-1500 and SIMOTION: LAcycCom library for acyclic communication
(https://support.industry.siemens.com/cs/ww/en/view/109479553),
FB LAcycCom_RTCSinamicsAcyclic
Note
If you want to implement time-of-day synchronization for SINAMICS S120 through a user
program or the NTP time-of-day synchronization, you need to deselect the option "By the
system" for "Time-of-day synchronization".
NTP time-of-day synchronization can be used for SINAMICS S210 drives independent of
this.
Additional information
For additional information, see SINAMICS S120 Communication function manual
(https://support.industry.siemens.com/cs/ww/en/view/109763284), "Time-of-day
synchronization between controller and converter".
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SIMATIC Drive Controller
System Manual, 11/2019, A5E46600094-AA