Allen-Bradley 1771-OBN High True Output Module

The Allen-Bradley 1771-OBN High True Output Module is a 32-point DC output module for PLC-5 systems, delivering four banks of eight high-true outputs that switch DC voltage to control loads. It operates from a 10–30 V DC supply and provides positive-logic (high-true) outputs, meaning a load is energized when the corresponding output is driven high. This single-slot module occupies a PLC-5 I/O chassis slot and is intended to drive DC devices such as relays, contactors, and solenoids in industrial control schemes. The module is specified for an operating environment of 0 to 60 °C and is part of the PLC-5 family’s modular I/O lineup, compatible with 1771-series backplanes. With 32 discrete outputs arranged as four groups of eight, it supports wiring of multiple DC loads and facilitates fault isolation across the four output banks. Commonly cataloged as 1771-OBN (and variants like 1771-OBN/A), this module remains a staple in legacy automation where DC high-true outputs are required for direct drive of 10-30 V devices.