The Allen-Bradley 1771-IL, also cataloged as the 1771IL Analog Input Module, operates as a dedicated hardware component for isolated bipolar analog signal conversion within Allen-Bradley PLC-5 1771 I/O chassis assemblies.

Ordering Reference & Model Architecture

• 1771-IL: High-resolution 8-point isolated analog input module processing voltage (-10 to 10 VDC) and current (-20 to 20 mA) field signals.

• 1771IL: Equivalent catalog designation denoting the 8-channel isolated input board configured for 1771 I/O slots.

Hardware Specifications Summary

Backplane Integration & Deterministic Communication

The unit executes analog-to-digital conversions across 8 isolated channels, sending 16-bit binary data values across the backplane bus communication velocity link. High-speed backplane throughput maintains deterministic execution across PLC-5 scanning loops. The internal circuit topology maintains firmware flash compatibility with host processors, supporting flexible I/O density scaling without bus congestion.

Package Inspection List

• 1 x 1771-IL Analog Input Module

• 1 x Field Wiring Arm Alignment Keying Plastic Clip

Mechanical Installation Guidelines

Chassis Insertion Protocols

• Insert plastic keying bands into the 1771 I/O backplane edge connector matching the module slot configuration.

• Align the circuit board edge with upper and lower card guides, sliding the module inward until the rear backplane connector locks into position.

Wiring and Shielding Standards

• Terminate all analog signal lines using shielded twisted-pair cables to restrict electromagnetic interference.

• Connect cable shield drain wires to frame ground at a single ground point to eliminate differential loop currents.

• Route signal wiring through independent conduits kept separate from high-voltage AC distribution power cables.

Technical Operational FAQs

• What input signal ranges does the 1771-IL support?

  The module processes analog voltage inputs from -10 to 10 VDC and analog current inputs from -20 to 20 mA across its 8 channels.

• What is the A/D conversion resolution of the input channels?

  The internal analog-to-digital converter delivers 16-bit binary resolution across the entire operating input signal range.

• How much current does the 1771-IL draw from the backplane?

  The module draws a nominal current load of 1.3 A (up to 1.4 A maximum) at 5 VDC directly from the 1771 chassis backplane supply.

• What is the internal update scan time for all 8 input channels?

  The internal circuit architecture completes a full analog scan cycle across all 8 isolated channels in 50 ms.

• Can the module be inserted or removed while backplane power is active?

  No. Backplane power must be fully isolated before module removal or insertion to prevent damage to backplane pin logic.

• Is channel-to-channel isolation provided on this module?

  Yes. The 1771-IL features individual galvanically isolated input channels to prevent inter-channel signal ground interference.

• What are the typical signal turn-off delay times for AC and DC inputs?

  The module exhibits a typical AC signal turn-off delay of 24 (+/- 10) ms and a typical DC signal turn-off delay of 20 (+/- 9) ms.

• What wire gauge range fits the field wiring arm terminals?

  The corresponding field wiring arm accommodates solid or stranded copper wire sizes from 14 AWG to 22 AWG.