18. Other functions
18.1 Date and time
18.1.1 Overview
The date and time can be set manually from PICUS or the display, or automatically obtained from an external time server.
The time is stored locally on each controller, and automatically synchronised between all of the DEIF controllers connected in the
same Ethernet network.
The alarms, logs, and display unit use the time.
Time master
The time master's time is synchronised to all the other controllers. The synchronisation is achieved by using a Network Time
Protocol (NTP) client and server system. The controller that has been powered ON for the longest time on the Ethernet network is
the time master.
When a new controller is added to the network, it fetches the time from the time master in the network.
If two Ethernet networks with DEIF controllers are joined, then the time from the network with the controller that has been powered
on for the longest is used.
If the time master fails, the controllers in the network determine which controller has been ON the longest. The controller that has
been on the longest, then becomes the new time master.
Synchronisation interval and performance
Each controller checks the time from the time master at regular intervals. The frequency of these checks adapts to the
synchronisation quality. If the synchronisation is poor, then the controller uses shorter intervals between checks.
The time difference can initially be a few seconds. This is adjusted down over time. The time synchronisation can take some time
(for example, 30 minutes) to synchronise the controllers.
Table 18.1
Date and time settings
Setting Range Default Notes
Time
• 00:00:00 to 23:59:59
• 12:00:00 AM to 11:59:59 PM
If an NTP server is configured, then you are not able to change
the time manually.
Time format
• 12 hour clock
• 24 hour clock
24 hour clock
The AM/PM selector for Time is only visible when 12 hour clock is
selected.
Date 2018-01-01 to 2037-12-31
If an NTP server is configured, then you are not able to change
the date manually.
Date format
• YYYY-MM-DD
• YY-MM-DD
• DD-MM-YYYY
• DD-MM-YY
• MM-DD-YYYY
• MM-DD-YY
YYYY-MM-DD
Time zone Selectable list Etc/UTC
The adjustment for daylight saving is based on the time zone, and
are automatically applied by the controller.
DESIGNER'S HANDBOOK 4189340911K UK Page 485 of 521
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