Allen-Bradley 1771-IAN 32-point Digital AC Input Module

Product Overview

The Allen-Bradley 1771-IAN is a 32-point digital AC input module for PLC-5 1771 I/O systems. It provides 120V AC input detection across four groups of eight inputs each, with optoelectronic isolation, noise filtering, and individual status LEDs for reliable discrete signal acquisition in industrial control applications.

Key Specifications

• Number of Inputs: 32 (4 sets of 8)
• Voltage Category: 120V AC/DC
• AC Operating Range: 85–138 VAC
• Frequency: 50/60 Hz
• Backplane Current: 280 mA
• Max AC Off-State Current: 3.0 mA
• Max DC Off-State Current: 0.8 mA
• Typical AC Delay (ON): 10 ± 7 ms
• Typical AC Delay (OFF): 20 ± 15 ms
• Input Isolation: Optoelectronic isolation
• Filtering: Input noise filtering
• Wiring Arm: 1771-WN
• Operating Temperature: 0–60 °C
• Dimensions: 3.5 × 6.5 × 2.0 in (89 × 165 × 51 mm)
• Weight: 1.2 lbs
• Series: A, B

Features & Benefits

• High Channel Density: 32 inputs in a single module slot maximizes I/O density in 1771 chassis
• 120V AC Compatibility: Direct interface with standard industrial AC switching devices
• Optoelectronic Isolation: Protects controller electronics from field-side electrical interference
• Individual Status LEDs: Each input features a dedicated LED for fast troubleshooting
• Service-Friendly Wiring: 1771-WN wiring arm allows module replacement without disconnecting field wiring
• Input Noise Filtering: Built-in filtering reduces false triggering from electrical noise

Applications

• AC limit switch and proximity sensor monitoring
• Pushbutton and selector switch interfacing
• Pilot light and annunciator status detection
• Motor starter auxiliary contact monitoring
• High-density discrete input panels

Installation Guide

1. Chassis Preparation: Install the 1771-IAN into a compatible 1771-series I/O chassis. Verify 280 mA backplane capacity.
2. Wiring Arm Installation: Attach the 1771-WN wiring arm for field terminal access. This enables RIUP (Removal and Insertion Under Power).
3. Field Wiring: Connect 120V AC field devices to the input terminals. Each of the 32 inputs has a dedicated terminal and common connection.
4. Group Configuration: Inputs are organized in 4 groups of 8. Wire each group according to application requirements.
5. Status Verification: Apply AC signals and verify individual input LEDs illuminate correctly for each active channel.

FAQ

Q: Does the 1771-IAN require external power?
A: No. The module draws power from the I/O chassis backplane. Field devices supply their own 120V AC signals.

Q: Can the 1771-IAN accept DC signals?
A: The module is optimized for AC signals (85–138V AC). DC compatibility is limited; verify specifications for DC applications.

Q: How are the 32 inputs organized?
A: The inputs are arranged in 4 groups of 8 channels each, with individual commons per group.

Q: What is the replacement for new installations?
A: For new designs, Rockwell recommends ControlLogix 1756-IA16I or 1756-IA32 modules.

Selection Tips

• Choose 1771-IAN when high-density AC input (32 points) is required in a single slot
• Verify field device voltage is within 85–138V AC range
• Consider total backplane current draw when multiple high-density modules are installed
• Use 1771-WN wiring arm for hot-swappable module replacement
• For DC input applications, evaluate 1771-IQ16 or 1771-IND modules