Ntp to KNX update

I tried to send the time from OH 1.8.1 to KNX 10.001 and 11.001 with two different items like this:
DateTime KNX_Datum { ntp=“Europe/Berlin”, knx=“11.001:7/7/0” }
DateTime KNX_Zeit { ntp=“Europe/Berlin”, knx=“10.001:7/7/1” }

In the config file i set a high update rate to see a result in the KNX Monitor, but the items are only tranmitted once at start of the Server or modifications in the items file.

Is this by design or did i make a mistake?

Seems, I’ve the same behaviour. My time on KNX meanwhile drifts away :frowning:
My Date item itself is refreshed every 15 minutes, but obviously the time isn’t forwarded to knx, as I can not find any packet sent to KNX with my ETS.

Regards Michael