Time Sources For A Pcs 7 Plant - Siemens SIMATIC PCS 7 Function Manual

Fundamentals
2.7 Time synchronization in PCS 7 - mode of operation
2.7.2

Time sources for a PCS 7 plant

Overview
In PCS 7 plants, it is necessary to define which component is capable of providing the plant
with a satisfactory time in terms of quality. You can use either internal or external time sources
for this purpose.
External time source
Suitability External time sources provide an ultra-
precise time and are suitable for all plant
configurations.
Examples ● GPS decoder
● DCF 77 receiver
● External NTP server
Internal time source for a PCS 7 plant
Using an internal time source ensures system-wide time consistency. This time does not have
to agree with real UTC or with real local time. The following table shows which internal time
source can be used for the time master:
Internal time source
BIOS clock of a central plant clock The central plant clock is connected to a PCS
BIOS clock of a domain controller The computer to be synchronized belongs to a
BIOS clock of an OS server
External time source for a PCS 7 plant
Using an external time source ensures system-wide time consistency. This time matches UTC
or local time. The following table shows which external time source can be used for the time
master:
External time source
DCF 77 or GPS signal
DCF 77 signal
GPS signal
NTP server
22
Requirement
7 plant network.
Windows 2000/2003 domain.
The real time is not important for the project.
Requirement
Radio signal synchronizes SICLOCK
The DCF 77 receiver is connected to a COM
interface of an OS server.
The GPS decoder is connected to a COM
interface of an OS server.
Internet connection
Internal time source
Internal time sources supply a continuous time signal. The
time provided does not have to match the local time or
Coordinated Universal Time (UTC).
Note:
Internal time sources are generally not approved for the
validation of processes.
BIOS clock for a component without external time
synchronization.
Active time master
Central plant clock
Domain controller
OS server
Active time master of the PCS 7 plant
Central plant clock
OS server with DCF 77 receiver
OS server with GPS decoder
Domain controller
Function Manual, 03/2012, A5E02779849-02
Time synchronization (V8.0)