Communication
14.1 Communication services
S7-400H
222 System Manual, 03/2012, A5E00267695-11
14.1.6 Time synchronization
Introduction
The S7-400 has a powerful timer system. You can synchronize this timer system using a
higher-level time generator, which will allow you to synchronize, trace, record, and archive
sequences.
Interfaces
Time synchronization is possible via every interface of the S7-400:
● MPI
You can configure the CPU as a time master or a time slave.
● PROFIBUS DP interface
You can configure the CPU as a time master or a time slave.
● PROFINET interface via Industrial Ethernet
Time synchronization using the NTP method; the CPU is the client.
Time synchronization using the SIMATIC method as master or slave
● Via the S7-400 backplane bus
You can configure the CPU as a time master or a time slave.
CPU as a time master
If you configure the CPU as a time master, you must specify a synchronization interval. You
can select any interval between 1 second and 24 hours.
If the CPU time master is on the S7-400 backplane bus, you should select a synchronization
interval of 10 seconds.
The time master sends its first message frame once the time has been set for the first time
(via SFC 0 "SET_CLK" or PG function). If another interface was configured as a time slave
or as an NTP client, the time starts once the first time message frame has been received.
CPU as a time slave
If the CPU is a time slave on the S7-400 backplane bus, then the synchronization is carried
out by a central clock connected to the LAN or by another CPU.
You can use a CP to forward the time to the S7-400. To do this, the CP (if it supports
direction filtering) must be configured with the "from LAN to station" option in order to forward
the time.
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