Hi everyone,
I have just setted up my openhab2 installation and would need some help.
I connected a homematic dimmer via homegear to openhab. This dimmer sits behind the normal light switches, so that hitting those will turn on/off the dimmer itself. What I want to achive is now in a first step that when I hit the normal light switch (read: when the dimmer gets powered on), the light goes on 
Unfortunately I cannot find a suitable trigger for a rule.
Without some definitions around your items it’s a little hard to give you specifics, but try
when
Item <item> changed from 0
then
That will capture when the dimmer starts to turn on the light, irrespective of what dim level it is going to. Similarly you can use “changed to 0” to trigger a rule when the dimmer turns off. Their will be a slight lag until the dimmer gets to the 0 set point.
Hi thanks for the reply,
this trigger will get handy leter on, but for now my problem is that there is no change in the dim level at start up of the Homematic dimmer.
In openhab speech: I want to perform an action when the thing comes online.
I observed some items I linked to it while switching the thing on & off. I tested for instance the signal strength but from the openhab console it seems that the latest value before switch off is just kept. So I cannot use it to check if the thing is online or not.
Sorry, unfortunately I don’t have any experience with the Homegear setup so can’t help you there.
Thanks anyway.
Does this mean there is no general aproach to pefrom an action when a thing comes online??
Seems too me like a quite basic feature 
It looks like something they are working on:
When I Googled it, I did find what looks like a potential work around using persistance to monitor the device state:
https://groups.google.com/forum/#!category-topic/openhab/rules/T-5-KbrX8nA