Allen-Bradley 1771-IAD | Digital Input Module

Overview

The 1771-IAD from Allen-Bradley is a sixteen-channel digital input module. It accepts AC and DC signals, supporting 120VAC and 125VDC voltages. This module provides precise signal detection for PLC systems, ensuring reliable industrial automation operations.

Compatibility

The 1771-IAD installs in 1771-A1B, A2B, A3B, A3B1, A4B, 1771-AM1, and AM2 chassis. Its universal design allows seamless integration across multiple 1771 series PLC configurations. The module interfaces with discrete devices such as pushbuttons, switches, and relay contacts.

Electrical Specifications

The 1771-IAD has a DC operating range of 79–138V and an AC range of 79–138V at 50/60Hz. The backplane consumes 195 mA, while the maximum AC off-state current is 2.8 mA. Typical DC signal delays are 3 ±0.1 ms or 10 ±1 ms, and AC delays are 5 ±3 ms. The module supports 16 inputs with a voltage category rating of 120V AC/DC.

Physical Specifications

The 1771-IAD measures 3.5 x 6.5 x 2.0 inches (89 x 165 x 51 mm) and mounts securely in standard 1771 chassis. It includes a 1771-WH wiring arm for organized connections. The robust construction ensures long-term durability in industrial environments.

Functionality

The 1771-IAD efficiently converts discrete AC or DC signals to the PLC backplane. Its precise timing and low off-state current allow consistent monitoring of switches, auxiliary contacts, and other field devices. This module enhances automation reliability while maintaining compact form factor for easy installation.