Allen-Bradley 1771-IAD PLC-5 Digital Input Module

Allen-Bradley 1771-IAD PLC-5 Digital Input Module is a 16-point AC/DC input module for the PLC-5 system, designed to read field digital signals from 120 V AC or 125 V DC sources. It accepts nominal 120 V AC or 125 V DC inputs, with a wide on-state range of 79 to 138 V and an on-state current of 5.95 mA at 79 V AC (60 Hz) or 1.5 mA at 79 V DC, enabling reliable sensing from common industrial sensors. Off-state conditions support up to 43 V and draw up to 3.0 mA at 43 V AC (60 Hz) or 0.8 mA at 43 V DC, helping resist unintended triggering. The module’s input network presents 11.2 kΩ impedance at 60 Hz and includes conditioning components (0.18 μF in parallel with 47 kΩ, in series with 820 Ω) to damp noise and improve stability. Input change delays are selectable: Off-to-On for 120 V AC 60 Hz is 5 ms or 20 ms; for 120 V DC it is 3 ms or 10 ms, with broader timing options noted for mixed configurations. Power dissipation ranges from 8.8 W maximum to 1.0 W minimum depending on voltage and activity. Rated for 0–60°C operating temperature (and broader storage range) and 5–95% non-condensing humidity, it’s intended for use in PLC-5 backplane racks in 1771-series I/O architectures and is commonly paired with a 1771-WH wiring arm for field wiring. This Series C revision preserves the PLC-5’s rugged 16-channel digital input capabilities.