Allen-Bradley 1746-A2 SLC 500 2-Slot Expansion Rack

Allen-Bradley 1746-A2 is a two-slot expansion rack for the SLC 500 family, marketed as a fixed I/O expansion chassis that adds two expansion slots to a SLC 500 backplane. It is designed for use with the original fixed-style SLC controllers (such as the SLC 100) and is compatible with SLC 500 modular or fixed backplanes, enabling additional I/O without replacing the main processor. The two expansion slots accept 1746-series I/O modules, allowing closer-to-field connections and more compact wiring in small to mid-size automation setups. Common use cases include extending discrete I/O for sensors, actuators, and limit switches in manufacturing lines or basic process-control tasks, where expanding the controller’s I/O footprint with a compact 2-slot rack is advantageous.