Allen-Bradley 1746-IA4 4-Point DC Input Module

The Allen-Bradley 1746-IA4 is a four-point AC input module for the SLC 500 PLC family, designed to bring four field signals into the controller via the 1746 backplane. Each input is rated for 100/120 VAC operation with an operating range of approximately 85 to 132 VAC at 47 to 63 Hz, enabling direct wiring of standard AC devices such as pushbuttons, limit switches, and other line-powered sensors. As part of the 1746 modular I/O system, the IA4 plugs into a compatible SLC 500 I/O rack and reports the on/off state of its four discrete inputs to the CPU through the backplane, supporting straightforward wiring in industrial automation environments. Typical applications include start/stop circuits, machine safety interlocks, and general-purpose sensing on manufacturing lines where AC voltage-level signals are already used for control logic. Manufactured by Allen-Bradley (Rockwell Automation), the 1746-IA4 is one of the legacy SLC 500 input modules optimized for reliable, in-plant integration and long-term availability within established control systems.