Product Summary
The Allen-Bradley 1771-IAD is a core component for your automation network. This discrete input module handles 120V AC or DC signals from field devices. It provides 16 input channels inside a single slot for efficient control. Engineers use it to connect pushbuttons and limit switches to a PLC-5 processor.
Why Choose the 1771-IAD Module?
This module solves a key industrial pain point for procurement teams. It simplifies inventory by accepting both 120V AC and 125V DC power. You no longer need separate cards for different voltage types. The 1771-IAD works across an operating voltage range of 79 to 138 Volts. This flexibility reduces costly downtime during system upgrades or replacements.
Application engineers also benefit from selectable input signal delays. For AC signals, you choose a 5 millisecond or 20 millisecond on-delay. For DC signals, you select a 3 millisecond or 10 millisecond on-delay. This feature lets you fine-tune the module for noisy environments. It prevents false triggers from transient electrical spikes in the field.
Step-By-Step Installation Guide
Begin by selecting a compatible 1771 chassis for this module. The unit fits models A1B, A2B, A3B, A3B1, and A4B. It also works in the 1771-AM1 and AM2 remote chassis. Always power down the system before inserting the card.
Set the keying bands correctly to avoid damaging the backplane. Position the upper key between pins 14 and 16 on the connector. Place the lower key between pins 10 and 12. This physical keying ensures you install the module in the correct slot.
Next, connect the 1771-WH wiring arm to your field devices. This removable arm works like a terminal block for easy wiring. You can replace the entire 1771-IAD module without disconnecting individual wires. This feature significantly speeds up maintenance tasks in the field.
Verify the backplane current draw of 195 milliamperes at 5 Volts. Ensure your power supply can handle this load along with other modules. The total power dissipation reaches a maximum of 8.8 Watts. Confirm adequate airflow to keep thermal dissipation below 30.1 BTU per hour.
Performance Metrics and Diagnostics
The module provides 16 red status indicators on its front panel. Each LED corresponds to one input channel for quick troubleshooting. A single green LED confirms the module is active and communicating with the processor.
Signal timing is critical for discrete control applications. The off-delay for both AC and DC signals is 25 milliseconds with a tight 5-millisecond tolerance. This consistent performance allows for reliable monitoring of safety circuits. The maximum off-state current is only 3 milliamperes for AC inputs. This low leakage current prevents false readings on sensitive digital inputs.
Logistics & Standard Packaging Details
