semaphore TBOX LT2-530 Series, User Manual, Page: 178 / 197

Version : 1.09 178
Day Light Saving (Winter/Summer time)
When installed in regions using daylight saving,
TB
OX
LT2
handles the changing automatically.
It means that RTC and Analog System Variable [hour] are automatically updated when the time changes.
Standard changing date and time in Europe:
-
last Sunday of October: 3:00

2:00
-
last Sunday of March: 2:00

3:00
B.2. Data logging
Chronologies
In chronologies, timestamp is recorded for each log of data. The timestamp recorded is the UTC time.
When generating data,
TB
OX
LT2
converts UTC timestamps into local timestamps according to its Time
Zone.
When retrieving data from a PC, the latter reads UTC timestamps and converts them according to the local
time of the PC, depending on the time settings of the PC.
When a daylight saving change occurs,
TB
OX
LT2
is informed and automatically adapts all coming
timestamps to the new time.
Sampling tables
In sampling tables,
TB
OX
LT2
records the timestamp of the last record only. The previous timestamps are
built up when retrieving the data, based on the last timestamp and the period of recording.
Conversion into local time is done as above with chronologies.
A choice had to be made concerning periods > 1 hour: either having always the same period of recording
or having always the same “hour” of recording. The latter case has been chosen. When daylight saving
change occurs, the target time is automatically updated for sampling tables having a period > 1 hour.
Example:
If recording a value once a day at 6.00 in the morning, the recording will always happen at 6.00, but when
changing from winter to summer (in Europe), the sampling period will be 23 hours and when changing
from summer to winter the period will be 25 hours.
Periodic events
When a periodic event is defined with a period > 1 hour, its target time is automatically adjusted when a
changing winter/summer happens.