This read-write setting selects which warning mechanism fires when digital input 2's state changes, mirroring eventDI1ChangeEvent for the second digital input line. An admin configures a distinct alert channel here so the alert source alone identifies which of the two sensors changed state. For example, wiring a separate motion sensor to digital input 2 and enabling this alert lets staff tell from the alert type alone which of two physical sensors triggered, without needing to check both inputs manually.