Central clock assembly

摘要

The system has slave clocks (NU1-NU5) attached to a central clock (ZU) over a data network i.e. local area network (LAN). The central clock transmits time information and actual time zone to the slave clocks using a network time protocol (NTP) and a multicast protocol respectively. The slave clocks determine actual time from the received time information and the time zone. The slave clocks are divided into time zone groups (ZZG1, ZZG2), and a determined time zone is transmitted to each time zone group. The central clock periodically transmits a time zone table to the associated slave clock.