I think that i figured it out.
rule "Sonos volume op/ned bad"
when
Item sonos_bad_volume_op received command ON
then
var Number V = sonos_bad_volume.state as DecimalType
var Number H = V + 1
if (H>65) H = 65
postUpdate(sonos_bad_volume_v, H)
sendCommand(sonos_bad_volume, H)
end
My items:
Dimmer sonos_bad_volume "volume [%s]" {sonos="[bad:volume]"}
Switch sonos_bad_volume_op "Volume op"