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

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

Configured for signal retiming and physical network segment extension in ControlNet deterministic networks, the Allen-Bradley 1786-RPA/B (1786-RPA ControlNet Modular Repeater Adapter) provides direct physical/electrical execution. It serves as the primary base unit providing power distribution and backplane isolation for up to four secondary media repeater modules, supporting copper and fiber optic media conversions across complex control topologies.

Hardware Specifications

Backplane Bus Communication Velocity & ControlNet Retiming

The 1786-RPA/B enforces high-speed signal restoration across deterministic ControlNet segments. When transmitting high-frequency physical layer signals through extended coaxial or fiber links, propagation delay and signal attenuation introduce jitter. The 1786-RPA/B active electronics perform digital retiming on incoming data packets before passing them to the internal backplane bus. The internal backplane delivers 1.6 A at 5 VDC to power attached daughter modules (such as 1786-RPCD, 1786-RPFS, 1786-RPFM, or 1786-RPFRXL) without compromising signal synchronization or introducing frame alignment errors across up to 20 cascaded adapter nodes in series.

Frequently Asked Questions

Q: What is the maximum backplane power supply current available for attached expansion modules?

A: The internal backplane power supply delivers a maximum of 1.6 A at 5 VDC to adjacent repeater modules. Ensure total current draw from attached modules does not exceed this rating.

Q: How many repeater modules can be mounted to a single 1786-RPA/B adapter?

A: Up to four standard media modules (such as copper 1786-RPCD or short/medium-distance fiber 1786-RPFS/RPFM) can be connected. When using fiber ring modules (1786-RPFRL or 1786-RPFRXL), the expansion limit is restricted to two modules due to backplane power allocation and physical space limits.

Q: What insulation test standard applies to the 24 VDC supply terminal block?

A: The input power terminals provide continuous isolation up to 50 V and are factory dielectric withstand tested at 710 VDC for 60 seconds.

Field Installation Guidelines

Mount the open-style enclosure inside an IP54 or NEMA Type 4X rated industrial enclosure to protect against environmental contaminants. Maintain proper separation between high-voltage AC power lines and Category 2 communication wiring in compliance with Rockwell Automation publication 1770-4.1. Secure 24 VDC power connections to the removable terminal block using 24-12 AWG solid or stranded copper wire rated for at least 75 deg C. Ensure the chassis ground lug connects directly to the central panel earth ground bar using a low-impedance braided strap to minimize high-frequency noise interference on the ControlNet coax or fiber transceiver interfaces.