Allen-Bradley 1745-R2 Relay Board Expansion Unit

Allen-Bradley 1745-R2 Relay Board Expansion Unit, Series-B, is a replacement expansion module for SLC 100 controller systems that adds additional relay outputs to drive external devices. As part of the 1745 family, the unit is designed to be wired and interfaced using the same field wiring and terminal conventions as other 1745-series expansion modules, enabling integration with legacy AB PLC networks without rewriting logic. The 1745-R2 serves in applications where more discrete control is needed—from signaling and interlocks to actuating mechanical devices like valves, pumps, and indicators—through isolated relay contacts that interface with external circuits. Because this is a Series-B replacement, it is intended to be a direct substitute for original hardware in existing installations, preserving compatibility with the controller's expansion topology and wiring conventions. This description reflects the product's role as a dedicated relay expansion unit rather than a standalone controller, making it a practical component for upgrading or sustaining older SLC-100-based systems.