The MODBUS Master sends the time to the slave(s) using function code 16 ("Preset Multiple Registers").
A slave adjusts the time taken from the telegram (taking into account the elapsed communication and internal processing time) and sets its internal clock.
The newly set time is written to the time synchronization registers so that the master can check that time synchronization was successful.
Note:     All fields must be provided in one-time synchronization telegram!
The number of registers has to be exactly four (4)!
The starting register is the register address of word number 1

For MiCOM Px4x, you can find the address in the menu database

Released for: Schneider Electric India