Allen-Bradley 1756-IB32 Discrete Input Module

The Allen-Bradley 1756-IB32 is a 32-point DC input module for Rockwell Automation's ControlLogix system, designed to monitor digital sensors in industrial automation. It accepts 10–31.2 V DC inputs across 32 discrete channels wired via a 36-pin terminal block, arranged as two groups of 16 inputs for straightforward wiring in a ControlLogix chassis backplane. The module, typically used in backplane-powered ControlLogix projects, contributes to backplane power dissipation up to 6.2 W at 60 °C (21.1 BTU/hr) and draws about 120 mA from the 5.1 V backplane supply and 2 mA from the 24 V supply (total backplane power around 0.66 W). Electrical characteristics include an on-state current of 4.8–5.5 mA across the 10–31.2 V range, an off-state current up to 2.27 mA, and an off-state voltage maximum of 5 V. Input impedance is specified at approximately 5.67 kΩ when measuring at 31.2 V. Response is configurable via a software filter (0, 1, or 2 ms) with hardware delays: 380 µs max from input to backplane plus the selected filter, and an on-to-off delay of 420 µs max plus the filter. Typical applications involve reading signals from pushbuttons, limit switches, and proximity or other 24 V DC sensors in manufacturing lines, packaging machinery, and broader automation where dense digital I/O is required. The IB32 is part of Rockwell’s Series B family of DC digital I/O modules and is intended for installation in a compatible 1756 backplane within a ControlLogix chassis.