Allen-Bradley 1771-IAD IO Module

Allen-Bradley 1771-IAD is a 16-point digital input module for the PLC-5 family (Series D) that provides 16 discrete input channels to the controller from field devices. It accepts AC or DC input signals in the 79–138 V range, designed for 120 V class sensors and switches, enabling direct connection to standard 120 V field devices. The module mounts on a PLC-5 backplane and feeds the processor’s data table with 16 digital inputs, making it suitable for reading on/off signals in automation lines. Documentation identifies this model as a Series D 16-input AC/DC input module, reflecting its role within the 1771 I/O family for PLC-5 installations. Rockwell Automation lists the 1771-IAD as discontinued, with a discontinuation date of March 10, 2020, and categorizes it under Engineering Replacement for legacy systems. The 1771-IAD is referenced alongside other 1771 digital input modules and is available under the part number 1771-IAD, reinforcing its place in historical PLC-5 configurations that relied on the 1771 I/O backplane.