How can I avoid the part with the drumkit assigned to, and the arpeggiator switched on, to be triggered (played) also by another part in the same performance ? When I play the performance, not only the drumpart is started by playing the keyboard, but the individual drum sounds also sound when I play the piano part, and that is not what I want. I searched for a slution for some hours now, but I can't find the parameter(s) to avoid this ...
There are many factors that come into play when assigning an Arp to a Part. There are different kinds of Arpeggio phrases; there are different Key Modes; the Key Mode determines how the ARP behaves in response to you triggering it. This determines whether or not your direct key presses are heard or not;
When creating your own Performances it pays to know what type of phrase, what Key Mode is selected, and if any of the advanced Play FX (random or accented functions) are active. The Data List indicates those Arps with Accent and/or Random effects.
In general, if you have selected an Arp Type that is Note-On phrases (like a drum ARP), and the KEY MODE is either "sort" or "thru", then your direct key presses will not be heard as long as the ARP On/Off Switch is On. Your initial key press will simply start the phrase.
If you have "Accent Velocity Threshold" active then triggering a key at or above the set velocity threshold will cause an "accent" (usually a kick + crash)... check to make sure this is set properly or to "Off" if you wish not to use the Accent function.
What ARP are you using?
Does it feature an Accent triggered by Velocity?
What Key Mode are you using?