Dimmer items accept an OnOffType state, but ON and OFF are converted to 0 and 100 respectively. The actual dimmer state is a PercentType (0-100). The OR group summary operator will return the first value (ON) if at least of the group items has that state, otherwise it will return the second value (OFF). None of the dimmer items literally have the ON state (although they may be at 100 percent), so OFF is always returned. This is consistent with the mySQL errors in the log.
I’m not exactly sure what you are trying to accomplish with the OR(ON, OFF) summary but if you used OR(100, 0) instead it should work for persistence although the value will be zero even if all dimmer items are at 99 (for example). If you use OR(0, 100), then the value would be 100 if none of the dimmer items are set to 0. Othewise, maybe a MAX or MIN summary would work better for you.
thanks a lot for your quick answer I was already thinking that I might have provided too less information for good understanding of my setup. Also thanks for your explanation of how group items work - wasn’t that clear to me.
Setup:
basic system is KNX
above mentioned lights are Philips Hue
integration is done via OH with KNX and Hue binding
the idea behind the group dimmer is to steer all lights of one room (Group) together
Do you see any better possbilities to implement this?
015-10-19 16:12:21.360 [ERROR] [i.internal.GenericItemProvider] - Group function 'OR' requires two arguments. Using Equality instead.
2015-10-19 16:12:21.360 [ERROR] [i.internal.GenericItemProvider] - Group function 'NOT AND' requires two arguments. Using Equality instead.
2015-10-19 16:12:21.360 [ERROR] [i.internal.GenericItemProvider] - Group function 'OR' requires two arguments. Using Equality instead.
2015-10-19 16:12:21.360 [ERROR] [i.internal.GenericItemProvider] - Group function 'NOT AND' requires two arguments. Using Equality instead.
Long answer: every bulb of Philips Hue can be steered individually but in many cases I just want to adjust brightness for the whole room which means to dim the lights of a group of hue bulbs --> group dimmer.