I believe that @Udo_Hartmann wants to be able to be able to have the Item [...] received command in OH2 when he presses the knx rocker.
In KNX1, such an action produced a command in OH2.
In KNX2, such an action produces a state update (I prefer this personally and as a result, I only use 1 “regular/non-control” Channel) 
To “replicate” KNX1 behavior, he is using the -control version of the Channel.
The -control version is useful when you have the Item bound to more than 1 bindings (e.g. knx + zwave)
You need the received command in such a scenario in order for OH2 to trigger the other binding also.