Click the ON button in the Enable by Articulation column.
The articulation ID number appears in the Value column. For included software instruments that use articulations, the group name usually reflects the articulation associated with the ID number. For example, Brass Falls.
An instrument may have a series of groups set to the same note range, each set to use a different articulation. When a note event in the specified range occurs, only the group whose articulation Value corresponds with the articulation ID number for the note event plays.
Vertically drag the numeral in the Value column to set the articulation ID number for the selected group.
You can route a modulation source, such as a MIDI controller, to an Articulation ID target parameter. This lets you dynamically change or switch between articulations using the source MIDI controller.
In Logic Pro Sampler, click the Navigation bar Mod Matrix button to view the Mod Matrix pane.
Click the Plus button (+) to create a new modulation routing.
In the modulation routing, choose the controller you want to use from the Source pop-up menu.
For example, you could assign a MIDI foot pedal to switch between two layered groups: one containing a bowed string section and the other containing a plucked string section.
Choose Articulation ID from the Target pop-up menu.
Drag the Amount slider all the way to the right, so it is set to 100%.
When you manipulate the controller, the articulation ID changes through the range of used values.
Download the guides:
Logic Pro User Guide: PDF