Store time to an item when presence was detected

my KNX-Sensor for presence sends “on” to a switch in openhab. Some time ago i saw a rule, which stored the time of last presence detection to an item and showed this on the sitemap. But now i can´t find it anymore.

With habmin i can see, when presence was detected during a time period. But how can i store the time to an item and show it on the sitemap?

Do you have any other suggestions what i can do with this presence item? Show some statistics or something like that?

Was this it: