You can connect up to 8 digital input signals to the DT7816 module. Refer to the DT7816 User's Manual for more information on the digital input features.
The figure shows how to connect digital input signals (lines 0 and 1, in this case) to the Digital I/O header on the DT7816 module; you can access these signals using the Digital I/O connector of the STP781x screw terminal panel: