Hello #dP;

Here is the Clock data (taken from the Technical Data of each) from CPUs and HMIs that fir your description:

CPU 1212 - 6ES7212-1HE40-0XB0RTC :Deviation per day, max.:+/- 60 s/month at 25 °C

CPU 1214 - 6ES7214-1AG40-0XB0RTC :Deviation per day, max.:+/- 60 s/month at 25 °C

KTP 600 Basic - 6AV6647-0AD11-3AX0 : no RTC, software clock only. synchronizable

KTP 700 Basic -  6AG1123-2GB03-2AX0: RTC available, no more details

So basically the RTC of both CPUs and of the KTP 700 can act as time masters for the synchronisation of the other components.

How do you synchronize the time of the HMI Basic Panel with an S7-1200 PLC?

Clock synchronization between a HMI operator panel and a SIMATIC PLC

If the one minute per month deviation of the S7-1200 CPUs is not acceptable you should look at an external time master, GPS-based for example.

How can you determine the coordinates and synchronize the system time of the S7-1200 using a commercially available GPS receiver?

Hope this helps,

Daniel Chartier