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3 - Communication
3�7 NTP – Network Time Protocol
In NTP, network devices obtain the current time from an NTP server
and use it to synchronise their internal clocks. From release 3.4, WMPro
has a built-in NTP client. If the option is enabled, the internal clock is
regularly synchronised with a specied NTP server and adjusted if the
dierence is more than 5 seconds. So you never need to adjust the
clock manually if it runs slow.
3�7�1 NTP settings
The NTP settings are with the network settings in the LAN/DNS/NTP
tab under Communication. To activate NTP, specify an NTP server. You
might be able to use a name to specify the server but only if you have
also dened a DNS server and gateway. If DHCP is enabled you do
not need to do this manually. To deactivate NTP, simply delete all NTP
server addresses.
There is no need to restart the device to apply the NTP settings – they are used the next time the
server is polled. For example, if you change the interval from 24 to 0.5 hours, the changes will be ap-
plied when the rst 24 hour period has nished.
A WMPro carries out an initial NTP synchronisation a few minutes after restarting. Synchronisations
then take place according to the dened interval.
If synchronisation fails because polling takes too long, the process is cancelled. There is no new at-
tempt until after the next dened interval.
The polling interval species how often the WMPro will obtain the time from the NTP server. The
timeout and the number of retries dene what happens if polling fails.
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