Allen-Bradley 1771-IAD 16-Point Digital Input Module

The Allen-Bradley 1771-IAD is a 16-point digital input module for the PLC-5 system that accepts 120V AC or 125V DC input signals. Each of its 16 input channels provides digital input status to the PLC‑5 controller, enabling ladder logic to respond to field signals in real time. The module supports an AC/DC input range of 79–138V, with a nominal 120V AC or 125V DC per channel, making it suitable for either AC- or DC-powered sensors in PLC-5 installations. As part of the 1771 I/O family, the 1771-IAD is designed to plug into a PLC-5 backplane and report input status to the processor for deterministic control of automation tasks. Typical use cases involve reading 120V-level signals from sensors and switches in industrial control panels, where reliable 16-channel digital input coverage is needed for sequencing, interlocks, and condition monitoring. Key specs include 16 input points, nominal 120V AC at 50/60 Hz or 125V DC input, and compatibility within the PLC-5 hardware ecosystem.