1771-AF | Allen-Bradley PLC 5 | Fiber-Optic Converter Module

Product Overview

The 1771-AF is a high-performance communication interface within the Allen-Bradley PLC 5 ecosystem, designed to bridge coaxial and fiber-optic media. This module allows industrial networks to overcome distance limitations and electrical interference by converting standard coaxial signals into optical pulses. By utilizing the 1771-AF (PN: 1771-AF), engineers can extend the reach of Remote I/O (RIO) or Data Highway Plus (DH+) links while ensuring complete galvanic isolation between segments.

Technical Specifications

• Manufacturer Allen-Bradley / Rockwell Automation

• Product Line PLC 5 / 1771 Universal I/O

• Model Number 1771-AF

• Module Type Fiber-Optic Converter

• Communication Rates 57.6 kbit/s and 115.2 kbit/s

• Backplane Current (5V DC) 1.0 Ampere

• Current Load (Total) 600 mA

• Power Dissipation 5 Watts

• Thermal Dissipation 17.06 BTU/hr

• Slot Requirement Single (1) slot in any 1771 I/O Chassis

• Coaxial Media Compatibility Quad-Shield RG-6 Cable

• Upper Connector Keying Between pins 54 and 56

• Lower Connector Keying Between pins 16 and 18

• Shipping Weight 1.25 lbs (0.57 kg)

Network Integration and Configuration

The 1771-AF acts as a transparent media converter, meaning it does not require complex software configuration to operate. It is typically deployed in pairs to create a fiber-optic backbone between two coaxial segments. This setup is particularly effective in environments with high electromagnetic interference (EMI) or where the distance between chassis exceeds the limits of standard copper cabling.

Installation and Keying

To ensure proper hardware alignment and prevent accidental damage, the 1771-AF utilizes specific plastic keying bands on the backplane connector.

• The upper keying position is set at 54-56.

• The lower keying position is set at 16-18.

  The module is designed for hot-swapping in many 1771 chassis, though it is best practice to verify system state before removal to avoid disrupting active network traffic.

Frequently Asked Questions

• Does the 1771-AF support 230.4 kbit/s communication?

  Based on original specifications, this module is optimized for 57.6k and 115.2k baud rates. For higher speeds or ControlNet applications, specialized 1771-series fiber adapters may be required.

• Can I mix fiber-optic and coaxial devices on the same segment?

  The 1771-AF is designed precisely for this purpose. It allows you to run fiber between buildings or through noisy areas and then transition back to coaxial cable for local chassis connections.

• What type of fiber cable should be used?

  The module is typically used with glass fiber-optic cable. Ensure that the fiber core diameter and connector types match the specifications of the optical ports on the front of the module.