The AB 1771-IAN is a PLC 5 Digital AC/DC Input Module. It converts AC signals provided by user devices to the logic level needed by the processor. It directly controls the state of corresponding bits in the PLC data table. It contains various input devices such as pushbuttons, limit switches, pilot lights, motor starters, and annunciators to interface with on/off sensors and actuators. It has a modular design with space-saving and pocket-friendly means to add input to a PLC control system. It comes with a 1771-WN wiring arm to replace the module, eliminating the need to disconnect the wiring. It is a series A module and supports ½ and 1-slot I/O addressing.

The 1771-IAN module has 32 (4 sets of 8) inputs with a 120V AC/DC voltage category. It has an operating voltage range of 85 - 138V AC. It has a typical signal delay of 10ms (±7) at on-AC state and 20ms (±15) at off-AC state. It has a maximum off-state current of 2.3mA at 60Hz and 1.9mA at 50Hz and a backplane current load of 280mA. It has a maximum power dissipation of 7W and thermal dissipation of 24.1 BTU/hr. It is installed in a 1771 I/O chassis containing a PLC processor. Keying bands for putting it in the right slot are found between pins 20 and 22 for the upper connector and between pins 16 and 18 for the lower connector.

The 1771-IAN module has 32 red status indicators on the front panel. It contains optoelectrical isolation to protect the system circuits from electrical transients. It also contains an input filtering feature to reduce electrical noise.