Logic Pro X Delay line objects overview
A delay line object repeats (echoes) MIDI events passing through it, at intervals ranging from one tick to 256 whole notes.
Create a new delay line object
Choose New > Delay Line.
As with the arpeggiator, you need to place a delay line object in the MIDI signal path, and Logic Pro must be in playback mode. The echoes of each incoming event are sent, sequentially, to each cabled output of the delay line object: event 1 to cable 1, event 2 to cable 2, and so on. Obviously, if only one cable is connected, then all events are sent to that output.
The delay line can send up to 99 repeats, at intervals ranging from one tick to 256 whole notes. You can also suppress the original note events.