There are several ways to control the clock
If your instrument has installed option for GPS and the GPS receiver has received a GPS fix and the GPS signal is good enough for exactly time setting, you are allowed to synchronize the instrument with the GPS time.
The instruments you want to synchronize must be connected with the Nor4633 sync cable. One of the instruments must be set to Sync mode 'master', the rest of the connected instruments must be Sync mode 'Slave'.
Use the Nor4633 cable and connect it to the 15 pin connector at the bottom of the instruments. Connect the 'out' from the master unit to the first slave units cable, labelled 'in'. Then connect the 'out' from the first slave unit to the next slave units 'in' and so on. The out signal is found on DO-3 (pin3) and the in signal is on DI-3 (pin 10).
When all connections are completed and Sync mode set in all instruments, select 'Sync clocks NOW' at the master instrument. You should get a message at the slaves displays that the clock is synchronized.
Will do a simultaneous sampling of real time clock on all instruments connected for synchronized real time clocks.
After 'Simultan. RTC sampling' is done, the resulting simultaneous real time can be seen here with a resolution of microseconds.