Allen-Bradley 1771-IBD Input Module

The Allen-Bradley 1771-IBD Rev. E03 input module is a 16-point digital input card for PLC-5 backplanes and 1771 I/O chassis, designed to monitor DC signals from 10 to 30 V and present clean logic-level inputs to the controller. It provides 16 independent DC input channels suitable for sensing switches, sensors, and other 24 V DC field devices in legacy automation systems. Each input draws about 4 mA at 10 V and up to 12 mA at 30 V, with an input impedance of approximately 2.5 kΩ (maximum), and inputs guarantee on-state at 10 V minimum and off-state below 6 V maximum. The module backplane load is about 130 mA, and under maximum conditions it dissipates up to 6 W. This Series B card (Rev. E03) fits standard 1771 I/O racks and wiring, making it compatible with PLC-5 and related 1771 backplane architectures. Typical applications include converting contact closures and sensor signals into PLC-5 logic, supporting sequencing, start/stop interlocks, and safety-related input wiring where discrete 10–30 V DC signals are required. With its 16-channel density and straightforward wiring, the 1771-IBD simplifies expanding digital input points in older Allen-Bradley control installations while maintaining reliable performance within its specified voltage range.