Allen-Bradley 1745-E156 SLC 150 Expansion Unit

The Allen-Bradley 1745-E156 SLC 150 Expansion Unit is a discrete I/O expansion module for the SLC 150 family that adds additional I/O capacity to a running PLC system. This expansion unit is a TRIAC-based module designed to switch AC loads through isolated digital outputs and provides 112 discrete I/O points, enabling more devices—motors, actuators, indicators, and sensors—to be controlled from a single SLC 150 controller. It connects to the main SLC 150 processor via the standard expansion bus and is intended for installation in the same rack or an adjacent slot to simplify wiring and keep the control panel compact. The E156 expansion units are part of the SLC-150 expansion ecosystem, allowing scalable configurations by mixing expansion modules to meet application needs. Common applications include automation tasks in small-to-mid sized panels where expanded discrete I/O is required for motor control, valve actuation, digital signaling, and sequencing logic, all without replacing the core controller.