Allen-Bradley 1771-IB 16-Point DC Input Module

Allen-Bradley 1771-IB is an 8-channel DC input module designed for use in the PLC-5/SLC 500 Universal I/O backplane, accepting 10–27 VDC inputs with 12–24 V nominal operation. Each of its eight inputs draws about 8 mA at 12 V or 24 mA at 24 V, enabling reliable sensing of digital field devices across the 12–24 V DC range. The module is intended to wire to three-wire input devices and supports stranded conductors in the 14–16 AWG range; official installation data describe suitable field wiring practices for 1771-IB modules. In practical use, it serves to monitor digital signals from devices like pushbuttons, limit switches, and proximity sensors, feeding PLC-5/SLC 500 controllers via the module’s backplane. This model is described as a 12–24 V DC input module, aligning with Allen-Bradley’s DC input family for discrete, on/off signaling in industrial control applications.