Allen-Bradley 1771-IAN AC Input Module

The Allen-Bradley 1771-IAN is a 32-point AC input module for the 1771 I/O family that accepts 85–138 V AC signals and feeds them into an SLC 500 backplane. It divides the 32 inputs into four 8-point groups and uses the 1771-WN wiring arm for field wiring, making it a straightforward way to monitor multiple AC devices in a single rack. Electrical specs include a nominal 120 VAC operating voltage at 50/60 Hz, a backplane current draw of up to about 280 mA at 5 V DC, and per-channel input current around 8.2 mA at 115 VAC (60 Hz) or 6.8 mA at 115 VAC (50 Hz). Timing characteristics feature a typical AC on-delay of about 10 ms and an off-delay of about 20 ms, with tolerances that accommodate common industrial signal fluctuations. The module is identified as Series A, with addressing support that fits 1/2-slot, 1-slot, or 2-slot configurations depending on the chassis, and it is compatible with 1771 Series A and B backplanes. This 32-channel AC input module is designed to read digital AC signals from field devices such as sensors and switches and present them to the PLC’s data table, enabling reliable, scalable input capture in legacy SLC 500 installations.