Allen-Bradley 1771 Modules: 1771-IFF/A Analog Input Module

Technical Dossier

Product Details And Specifications

Allen-Bradley 1771 Series Technical Notes

The Allen-Bradley 1771 I/O system is the foundational hardware platform of the Rockwell Automation PLC-5 programmable controller family. Deployed across global heavy industry — including petrochemical refineries, nuclear power generation facilities, offshore platforms, and continuous-process chemical plants — the 1771 backplane architecture has accumulated decades of installed base that remains active in brownfield facilities worldwide. The 1771-IFF/A is a single-slot, 8-channel analog input module rated for 4–20 mA and 0–10 VDC signals, designed for direct integration into the 1771 I/O chassis. Its role in legacy DCS and hybrid control architectures makes it a critical spare part for facilities that cannot justify a full PLC-5 to ControlLogix migration.

1771 Full Catalog & Functionalities (SKU List)

Analog Input Modules

• 1771-IFF/A: 8-channel analog input, 4–20 mA / 0–10 VDC, single-slot, 12-bit resolution
• 1771-IFE/B: 8-channel analog input, voltage/current selectable per channel, enhanced diagnostics
• 1771-IFMS: 8-channel analog input, millivolt/thermocouple input, cold-junction compensation
• 1771-IR: 8-channel RTD input module, supports PT100/PT1000, 3-wire configuration
• 1771-IX: 8-channel thermocouple input module, J/K/T/E/R/S/B type selectable

Analog Output Modules

• 1771-OFE1: 4-channel analog output, 4–20 mA, 12-bit resolution, single-ended
• 1771-OFE2: 4-channel analog output, 0–10 VDC, 12-bit resolution
• 1771-OFE3: 4-channel analog output, ±10 VDC bipolar, 12-bit resolution
• 1771-OFE/A: 8-channel analog output, 4–20 mA, enhanced update rate

Digital Input Modules (DI)

• 1771-IA: 16-point AC digital input, 120 VAC, single-slot
• 1771-IB: 16-point DC digital input, 24 VDC, sinking
• 1771-IC: 16-point DC digital input, 48 VDC
• 1771-ID: 16-point DC digital input, 125 VDC
• 1771-IG: 32-point TTL digital input, 5 VDC logic level

Digital Output Modules (DO)

• 1771-OA: 16-point AC digital output, 120/240 VAC, triac
• 1771-OB: 16-point DC digital output, 24 VDC, sourcing
• 1771-OBD: 16-point DC digital output, 24 VDC, sinking, diagnostic
• 1771-OW: 8-point relay output module, Form C contacts, 240 VAC / 24 VDC

Communication & Specialty Modules

• 1771-SDN: DeviceNet scanner module for 1771 chassis, Class 1 explicit/implicit messaging
• 1771-ASB: Remote I/O adapter, connects 1771 chassis to PLC-5 via Remote I/O link
• 1771-AENTR: EtherNet/IP adapter, bridges 1771 I/O to ControlLogix via EtherNet/IP

Quality Control for the 1771 Range

All 1771 modules processed by DriveKNMS undergo a structured inspection and functional test protocol. Analog input modules including the 1771-IFF/A are tested using calibrated signal sources across the full 4–20 mA and 0–10 VDC input range, with channel-by-channel verification of linearity, offset error, and gain error against published Rockwell specifications. Backplane connector pins are inspected under magnification for corrosion, mechanical deformation, and gold plating integrity. Modules with EEPROM-based configuration are read-verified prior to shipment. Digital I/O modules are cycled through all output states under rated load conditions. Communication modules (1771-SDN, 1771-ASB) are bench-tested against a live PLC-5 backplane to confirm node address recognition and data table read/write integrity. All tested units are shipped with a DriveKNMS inspection report documenting test date, technician ID, and pass/fail criteria results.