1771-IAD Allen-Bradley 16-Point Digital AC/DC Input Module

Product Introduction

The Allen-Bradley 1771-IAD module provides a high-density input solution for your PLC-5 control system. This module features sixteen discrete input channels that accept both 120V AC and 125V DC signals. It interfaces directly with field devices like pushbuttons, limit switches, and relay contacts. The module then converts these high-voltage signals into logic-level inputs that the processor can read.

Additionally, this module includes the 1771-WH field wiring arm. This removable terminal block lets you pre-wire all field connections before installing the module. You can quickly detach the arm during replacement without disturbing the existing wiring. Therefore, you reduce downtime significantly and simplify ongoing maintenance tasks.

Technical Specifications of the 1771-IAD

The Allen-Bradley 1771-IAD offers sixteen input channels with a voltage category of 120V AC/DC. The AC operating voltage spans 79 to 138 Volts, while the DC operating voltage also ranges from 79 to 138 Volts. This wide operating range ensures reliable performance even with fluctuating power supplies.

Moreover, this module features selectable signal delays for different applications. For AC inputs, you can choose an ON delay of 5 ms (±3 ms). For DC inputs, you have two options: a fast 3 ms (±0.1 ms) or a standard 10 ms (±1 ms). The OFF delay for both AC and DC is 25 ms (±5 ms). This flexibility allows you to optimize the module for either fast-response or noise-immune applications. The module draws a backplane current of 195 mA. It has a maximum AC off-state current of 2.8 mA and a DC off-state current of 0.8 mA.

Power Dissipation and Thermal Characteristics

The 1771-IAD module has excellent power efficiency for a 16-channel unit. Its maximum power dissipation reaches 8.8 Watts, while the minimum is 1.0 Watt. Correspondingly, the thermal dissipation ranges from 30.1 BTU/hr (maximum) down to 3.42 BTU/hr (minimum). These specifications help you calculate the overall heat load within your control cabinet accurately.

Mechanical and Installation Parameters

Physically, the 1771-IAD measures 3.5 x 6.5 x 2.0 inches (89 x 165 x 51 mm). It occupies a single slot in compatible 1771 series chassis. You can install it in 1771-A1B, A2B, A3B, A3B1, A4B, and also in 1771-AM1 and AM2 chassis. This broad compatibility makes it suitable for various legacy PLC-5 system configurations.

Furthermore, the front panel provides clear visual diagnostics. It features one green module active indicator and sixteen red status LEDs. Each red LED corresponds to a specific input channel and illuminates when that channel receives a valid signal. This design simplifies field troubleshooting considerably.

Installation and Keying Guidelines

Installing the 1771-IAD requires attention to proper keying for safety and correct operation. First, insert the module into any available slot within the compatible chassis. Ensure the backplane connectors mate securely. Next, verify that the system power supply can handle the 195 mA backplane load.

Proper keying is essential to prevent incorrect module insertion. For the 1771-IAD, you must install keying bands between pins 14 and 16 on the upper connector. Additionally, you need to place them between pins 10 and 12 on the lower connector. This physical keying mechanism protects both the module and the chassis backplane from potential damage.

Packaging List

Your shipment for the Allen-Bradley 1771-IAD module includes the following items:

• (1) Allen-Bradley 1771-IAD Digital AC/DC Input Module

• (1) Pre-installed 1771-WH Field Wiring Arm

• (1) Product Installation and Configuration Guide

All components come securely packaged to prevent transit damage. We ship all orders using trusted global carriers such as FedEx, UPS, and DHL.

Frequently Asked Questions (FAQ)

1. What is the main advantage of the 1771-IAD over the 1771-IA2?
The 1771-IAD offers sixteen input channels, twice the capacity of the 8-channel 1771-IA2. It also provides selectable signal delays and uses the 1771-WH wiring arm instead of the 1771-WA.

2. Can I select different delay settings for individual channels?
No, the delay setting applies globally to all sixteen channels on the module. You cannot configure different delays for different input channels individually.

3. Which chassis are compatible with the 1771-IAD module?
You can install this module in 1771-A1B, A2B, A3B, A3B1, A4B, and also in 1771-AM1 and AM2 chassis. It does not work with older non-Universal chassis types.

4. How do the red status LEDs help during troubleshooting?
Each red LED corresponds to one input channel. When a field device activates a channel, its LED turns on. This gives you immediate visual confirmation of which inputs are active without using a programming terminal.

5. What keying positions does the 1771-IAD require?
For correct installation, place keying bands between pins 14 and 16 on the upper connector. Also place them between pins 10 and 12 on the lower connector of the chassis backplane.