Configured for discrete AC voltage signal sensing in PLC-5 I/O chassis architecture, the Allen-Bradley 1771-IAN (1771IAN Digital Input Module) provides direct physical/electrical execution.

Module Configuration & Variants

• 1771-IAN: High-density 32-point AC digital input module operating at 85-138 VAC (50/60 Hz) nominal voltage logic levels.
• 1771IAN: Functional catalog designation denoting the 32-channel discrete input assembly for 1771 universal I/O backplane slots.

Engineering Specifications

Deterministic Bus & Signal Scaling

The unit processes discrete field signals across 32 individual channels, transferring state data through the 1771 backplane bus communication velocity architecture. Internal optocouplers isolate high-voltage AC field circuits from backplane logic processing. Firmware flash compatibility ensures synchronized scan times with PLC-5 processors, maintaining I/O density scaling across large I/O racks without dropouts.

Package Contents

• 1 x 1771-IAN Digital Input Module
• 1 x Field Wiring Arm Alignment Keying Band

Panel Mounting & Wiring Protocols

Chassis Insertion and Keying

• Insert keying bands into the 1771 I/O chassis backplane connector between pins 10-12 and 18-20 to prevent incorrect module substitution.
• Slide the module firmly into the chassis slot until the top and bottom retaining latches snap into position.

Wiring Routing and Grounding

• Route AC input conductors separately from low-level DC analog lines to prevent electromagnetic crosstalk.
• Connect field signal wiring to the 1771-WN field wiring arm, ensuring screw terminals are torqued to 0.9 Nm (8 lb-in).
• Ground the 1771 chassis frame directly to the panel enclosure ground bus using heavy gauge copper grounding wire.

Technical Operational FAQs

• What is the nominal operating input voltage range for the 1771-IAN?

  The module accepts input signal levels ranging from 85 to 138 VAC at a frequency of 50/60 Hz.

• How much current does the module draw from the 1771 backplane?

  The internal logic circuits draw a maximum of 250 mA at 5 VDC directly from the backplane power supply.

• Does the module support hot-swapping in an energized 1771 chassis?

  Removal or insertion under backplane power is not recommended and can cause processor fault conditions or contact arc.

• What signal isolation is provided between field terminals and logic?

  Optocouplers provide galvanic isolation up to 1500 VAC between field input terminals and the backplane logic.

• How are the 32 input channels grouped on the field wiring arm?

  The 32 input points are arranged in four isolated groups of eight channels each with dedicated common connections.

• What happens if an input voltage falls below 35 VAC?

  An input voltage below 35 VAC is recognized as a logic low (OFF) state by the internal input detection circuits.

• Are status indicators provided on the front panel for troubleshooting?

  Yes, individual active LED status indicators display the real-time ON/OFF state for each of the 32 input points.

• What wire gauge should be used with the field wiring arm?

  The field wiring arm terminals accept solid or stranded copper conductors ranging from 14 AWG to 22 AWG.