User Manual
Chapter 13
GFK-1503F
Jan 2020
Ethernet Communications
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NTP Server Time Clock: If time servers are configured and present on the network (see
chapter 6 for configuration details), the Ethernet interface’s built
-in clock is periodically
synchronized to the clock from one to three NTP servers on the network. The Ethernet
interface periodically requests time from the servers and uses the time from the most
accurate server (based on NTP stratum number).
Figure 209
All Ethernet interfaces that have been configured to use Network Time Protocol will have
updated, synchronized timestamps because they are all controlled by the NTP server clock.
Therefore, accurate timing comparisons between exchanged data can be made. For
example, if several PLCs sent alarm data, it might be helpful to know the order in which the
alarms occurred.
Multiple NTP servers can be used to improve the availability of time servers.
When the time is obtained from an NTP server, dates from January 1, 1970 are supported by
the Ethernet Interface.
13.4.5
Configuring NTP for the CPUE05 Ethernet Interface
This feature is supported in IC200CPUE05-HK and previous versions only.
To implement Network Time Protocol in the Ethernet interface in CPUE05, the IP address of
one to three NTP Time Servers are specified in the PLC Ethernet configuration. Refer to
chapter 6, the section, Configuring the Ethernet Interface for details. CPUE05 does not
support multicast NTP operation; multiple NTP servers may be specified individually.
The Ethernet interface in CPUE05 always operates in client mode. It will synchronize to an
NTP time server, but it will not synchronize other devices on the network.
Time synchronization takes multiple message exchanges to reach maximum precision.
Based on the default configuration of poll times, NTP synchronization should occur
approximately 2 minutes after a time server has been established.