What can I do with TRIGGER IN?

By connecting a foot pedal or a device that sends an audio signal which works as a trigger signal to the [TRIGGER IN] of this unit, you can control the play functions of this unit such as sequencer, arpeggiator, etc. This offers you a variety of performance options.

For details, please see "Using the [TRIGGER IN] of this unit to control the play functions of this unit" in the Operating Instructions of this unit.
You can download the Operating Instructions from the Pioneer DJ support page.