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AVANCE Y TECNOLOGÍA
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ANNEX I. TIME MANAGEMENT
As seen in Section 3.1,
the objects “Date” and “Time” show up by default in ETS when
configuring the device. These two objects are aimed at adjusting KES to the date and time of an
external KNX clock. However, KES has got its own internal built-in clock, so this two objects are
typically only necessary for eventually synchronising the internal clock to the external clock, for
example after a parameter download or upon voltage recovery after bus failures (the internal clock
only works under bus voltage). Therefore, in usual circumstances it is not necessary that the KNX
clock sends these objects whenever time or date change.
Consequently, every time KES is programmed or recovers voltage after a bus failure, these two
objects are sent to the bus as a request, with the intention of updating the internal clock according
to the time and date that are received as a response from the KNX external clock. If this request
receives no response after five seconds, KES will keep retrying by sending both objects up to three
more times (with a five-second delay from one to another). If no response is obtained after these
four attempts, KES will assume that the current time and date are those that the internal clock had
the last time it was working, or
–in case KES has been just programmed– that the current date is
January 1
st
2000 and the current time is 0:00 am.
Regarding cyclic sendings
–both the ones enabled from the General screen and the ones enabled
from each channel’s own screen–, it is important to remark that all of them will always take place
coinciding exactly with hour, day or week changes; never in the middle of two hours or two days or
two weeks.
Example I
:
If one security sending has been defined for every three hours and a parameter download (as
well as the consequent time set) takes place at 10:25h am, the first sending will be received at
1:00h pm (that is, three hour changes after the parameter download), not at 1:25h pm.
Example II
:
If one security sending has been defined for every two days and a parameter download (as well
as the consequent time set) takes place on Monday at 10:25h am, the first sending will be
received on Wednesday at 0:00h am (that is, two day changes after the parameter download),
not at 10:25h am on Wednesday.
