1786-RPA B Allen-Bradley | ControlNet Copper-to-Fiber Base

Allen-Bradley 1786-RPA Series B ControlNet Modular Repeater Adapter

Product Overview

The 1786-RPA (Series B) is a ControlNet Modular Repeater Adapter manufactured by Rockwell Automation. Serving as the foundation for the modular repeater system, this unit allows for significant network expansion and media flexibility. By utilizing the 1786-RPA, engineers can extend ControlNet segment lengths beyond standard limits and implement versatile topologies including star, ring, and point-to-point configurations. The module functions as a base that interfaces with copper (1786-RPFM) or fiber (1786-RPFS/RPFT) repeater modules, facilitating seamless media conversion and signal regeneration. Its scalable design supports a serialized chain of up to 20 adapters, ensuring robust communication across large-scale industrial distributed I/O and process control systems.

Technical Specifications

The 1786-RPA/B provides regulated power and backplane communication for attached media-specific modules.

• Manufacturer: Rockwell Automation / Allen-Bradley

• Model Number: 1786-RPA

• Hardware Revision: Series B

• Module Type: Modular Repeater Adapter

• Input Voltage: 24 VDC (18–36 VDC range) via removable terminal block

• Current Draw: 400 mA maximum

• Maximum Series Link: Up to 20 repeater adapters in a single series

• Media Support:

• Copper Coaxial (via 1786-RPTN)

• Fiber Optic (via 1786-RPFM, 1786-RPFS, 1786-RPFT modules)

• Status Indicators: LED diagnostics for Power and Communication status

• Isolation: 500V DC between power supply and ControlNet network

• Operating Temperature: 0°C to +60°C (32°F to 140°F)

• Storage Temperature: -40°C to +85°C (-40°F to +185°F)

• Dimensions: 4.0 x 4.0 x 3.0 inches (10.2 x 10.2 x 7.6 cm)

• Net Weight: 0 lbs 7.0 oz (0.2 kg)

• Mounting: 35mm DIN rail or panel mounting

• Lifecycle Status: Discontinued (Replacement engineering support recommended)

Key Functional Features

• Topological Versatility: The 1786-RPA/B allows for the transition from a linear trunkline to star or tree architectures, which is essential for routing ControlNet through complex facility layouts.

• Media Conversion Hub: Acting as a primary adapter, it allows for the integration of fiber optic modules, enabling ControlNet signals to travel long distances in high-EMI environments without electrical interference.

• Removable Power Supply: Equipped with a 24 VDC removable power connector, simplifying maintenance and allowing for module replacement without disturbing field wiring.

• Network Scalability: The adapter’s ability to support up to 20 units in series provides a highly scalable backbone for extensive industrial automation networks.