Interface	Quantity	Capability
Digital Input	24*	Contact closure sense, internally referenced, no external voltage needed
Digital Input	8	Voltage sensing, requires +5VDC for activation
Digital Output	8	Optically isolated FET switch, switches up to 50 mA through external loads
Analog Input	4	Potentiometer sense, use external reference voltage
Keypad Interface	1	4-row by 4-column keypad interface, requires state machine software
Display Interface	1	8 character Smart Display driver, requires state machine software
* 16 Digital Inputs available if simultaneously using 4 by 4 keypad interface

Basic discrete interfaces, such as digital inputs, digital outputs and analog inputs may be directly integrated into the ASTi sound model, using standard Model Builder software objects.

To run more complex control features like keypad decoders and display message libraries, additional software processes may be required. These control software processes, commonly called state machines, can run within the ASTi DACS node or from a customer's external host computer.

ASTi can also build custom control interface panels and develop state machine software to meet your requirements.

• Bare Board: User mounts the DDI in their own enclosure and provides wiring to the available interfaces.
• x2 Lansing Box: This enclosure is twice as tall as the RIU. The 8 DI and 8 DO connectors are on the front panel, while the 4 AI and remaining 16 DI connectors are positioned on the back panel.

See the links in the right-hand sidebar for additional DDI-related information.