Master Time keeper update

ABB IMS 10.20 UNIX master time keeper time was not updating and showing Jan 70.
Could any one tell us how set date and time.
Through SAM date was already set and showing current time.
Through set_parms command time was set and restarted the PC but showing as in system messages.
Problem was partially rectified as it seems there is a bug in the ABB DCS RTAB real time accelerator , after Jan 2020 mid night 12' clock on wards time re-set to 1970 ( i.e. 50 years time span).
As RTAB clock not broad casting, reverse synchronisation was done (i.e unix time clock to RTAB.)
Now IMS started functioning.
It seems all over world ABB unix AC460 machines will be having this kind of problem(Hisrorian). Temporary solution can be done as we did for our plant. As long as OS and IMS running there will not be problem once it reboots this problem will occur.

If any one knows how to reset the RTAB clock problem please share