1771-IA2 8-Channel AC/DC Input Module Allen-Bradley PLC5

Allen-Bradley 1771-IA2 120V AC/DC Digital Input Module – PLC5 Series

Key Technical Specifications

• Brand: Allen-Bradley | Catalog No.: 1771-IA2
• Module Type: 8-channel digital AC/DC input module for PLC5 systems. Intended for use with 1771-IA2 compatible AC/DC proximity switches.
• Voltage Range: Operates from 87-138V AC and 97-138V DC. Nominal 120V AC/DC category ensures broad compatibility.
• Signal Delays: AC On/Off delay typically 24ms (±10ms). DC On delay 10ms (±4ms); DC Off delay 20ms (±9ms). Built-in input filtering reduces electrical noise.
• Off-State Current: Maximum 2.8mA AC or DC ensures reliable off-state detection without false triggering.
• Backplane Load: Draws only 75mA from the 1771 chassis backplane. Power dissipation max 10.7W (36.5 BTU/hr).
• Isolation: Optoelectrical isolation protects logic circuits from electrical transients and voltage spikes.
• Physical Dimensions: 3.5 x 6.5 x 2.0 inches (89 x 165 x 51 mm). Keying bands between pins 10-12 (upper) and 4-6 (lower) for proper slot alignment.

Installation & Addressing

• Mounts in any single slot of a 1771 I/O chassis containing a PLC5 processor. Supports ½, 1, and 2-slot I/O addressing modes.
• Use the included 1771-WA wiring arm for field wiring termination. This removable arm preserves existing wiring during module replacement.
• Eight orange status indicators on the front panel provide immediate visual feedback for each input channel's on/off state.
• Series A module with straightforward configuration via PLC programming software.

Frequently Asked Questions (FAQ)

• Q: What makes the 1771-IA2 different from the standard 1771-IA?
  A: The 1771-IA2 is specifically intended for use with AC/DC proximity switches, though it functions identically to the 1771-IA for general-purpose 120V AC/DC inputs. Both share the same electrical specifications.
• Q: Can I use this module with 24V DC sensors?
  A: No. The 1771-IA2 requires 97-138V DC minimum. It does not operate at 24V DC levels.
• Q: What does the 2.8mA off-state current specification mean?
  A: It means the module tolerates up to 2.8mA leakage current without registering an ON state. This prevents false triggering from leaky proximity switches or long cable capacitance.
• Q: How do I replace the module without rewiring?
  A: Simply unplug the 1771-WA wiring arm from the old 1771-IA2, remove the module, install the new one, and reattach the arm. Your field wiring remains untouched.
• Q: What is the typical response time for proximity switches?
  A: AC proximity switches see a 24ms (±10ms) on/off delay. DC switches see 10ms (±4ms) on delay and 20ms (±9ms) off delay due to the module's input filtering.
• Q: Do you ship internationally, and what carriers do you use?
  A: Yes, we ship worldwide via FedEx, UPS, or DHL. We dispatch within 5 days of order confirmation.

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