Allen-Bradley 1771-IA Eight-Point Input Module

Allen-Bradley 1771-IA Eight-Point Input Module is a digital input card for the PLC-5 1771 I/O backplane that provides eight independent 120 V AC or 125 V DC input points for sensing field devices such as switches and sensors. Each of the eight inputs accepts either 120 V AC (nominal) or 125 V DC, with on-state voltages of 87–138 V AC or 97–138 V DC and off-state limits of up to 46 V AC peak or 57 V DC; nominal input currents are about 6.83 mA per channel at 120 V AC (50 Hz), 7.9 mA per channel at 120 V AC (60 Hz), or 7.4 mA per channel at 125 V DC. Off-state current is up to 2.8 mA, and input impedance is specified per the module schematic. The module’s input timing includes delays of 24 ms + 10 ms (AC off-to-on) and 24 ms + 10 ms (AC on-to-off), with 10 ms + 4 ms (DC off-to-on) and 20 ms + 9 ms (DC on-to-off). Power is drawn from the 1771 backplane, and the module dissipates up to 10.7 W (max) and as little as 0.4 W (min) across all channels. Designed for PLC-5 automation, it integrates eight discrete inputs in a single card and requires a compatible 1771 I/O chassis for operation; the 1771-IA is a discontinued module, with Rockwell documenting its sale as discontinued since July 31, 2017.