Allen-Bradley 1741-A120A Input Module

The Allen-Bradley 1741-A120A Input Module is a four-channel 120 VAC digital input card designed for use in an AB 1741 I/O rack. It accepts four independent 120 VAC input signals from field devices such as pushbuttons, limit switches, and other sensors, converting each to a boolean input for the controller. This module is part of the vintage SLC 500-era I/O family and mounts in the same backplane as other 1741 family modules, sharing common wiring and electrical characteristics with the series. Each channel is rated for standard 110/120 VAC operation, enabling straightforward integration with equipment powered from typical industrial mains. The 1741-A120A communicates with the PLC via the 1741 backplane, allowing the programmable controller to read on/off states in real-time and respond to process conditions accordingly. It is commonly used in machine automation, packaging lines, conveyors, and other manufacturing processes where AC-powered switches and sensors provide discrete control signals. As a four-channel module, it offers a compact option when only a few discrete AC inputs are required, complementing AB's broader range of input and output modules for legacy control systems.