Technical data

Glossary
Time synchronization (V7.1)
130 Function Manual, 03/2009, A5E01216578-01
Passive time master
A passive time master takes over the function of the active time master if the active time
master should fail.
RTC (Real Time Clock, hardware clock)
RTC is the internal, battery-operated clock of a PC. This clock continues to run even if the
PC is switched off and it has the precision of a quartz clock.
Stratum, strata
A stratum is a hierarchy level within time synchronization. Within a stratum, the time is the
same for all components.
● The time basis (precise reference time) within the entire system is designated as
stratum 0.
● Components that are directly linked to the time basis are designated as stratum 1.
● Any component within a stratum (n) that causes a time difference generates a new time
level stratum (n+1). The digit next to "stratum" indicates the number of time levels
between the time basis (stratum 0) and a stratum (n).
Time master
The time master is responsible for distributing the time signal within time synchronization. It
forwards the time signal to the PCS7 components that have been configured as time slaves.
The following time master types are available:
● Active time master
● Cooperative time master
● Passive time master
Time slave
The time slaves are PCS 7 components that receive time signals from the time master and
thus set their own clock.
Time synchronization
With time synchronization, the date and time of all time-dependent components are unified
by a time master.
UTC (Universal Time Coordinated)
UTC is a time basis specified by atomic clocks. It does not take daylight saving time into
account.