Allen-Bradley 1786-RPA ControlNet Modular Repeater Adapter

Configured for backplane bus power distribution and signal routing in ControlNet industrial networks, the Allen-Bradley 1786-RPA (1786-RPA ControlNet Modular Repeater Adapter Module) provides direct physical execution of repeater node expansion across modular fiber and coaxial networks.

Hardware Specifications

Deterministic Backplane Bus & Communication Architecture

The 1786-RPA serves as the primary base adapter for the 1786 modular repeater series, supplying 5 VDC backplane power up to a maximum threshold of 1.6 A to support up to four attached media daughter modules (such as 1786-RPFM medium-distance fiber modules). Operating at a deterministic communication velocity of 5 Mbps, the unit manages physical media conversion and signal reshaping across copper coaxial and optical fiber media segments without adding protocol latency. Internal isolation barriers protect backplane signal routing from ground loops and electrical interference present on external coaxial BNC connections.

Frequently Asked Questions

Q: What is the maximum current load the 1786-RPA backplane can supply to attached expansion modules?

A: The 1786-RPA base adapter provides up to 1.6 A @ 5 VDC across its backplane bus, which is sufficient to power up to four 1786 series daughter modules, provided their total combined current draw does not exceed this limit.

Q: Can the 1786-RPA operate as a standalone repeater without daughter modules installed?

A: No, the 1786-RPA functions as the power supply and backplane adapter base. It requires at least one attached 1786 media repeater module (such as 1786-RPFM for fiber or 1786-RPCD for coaxial) to execute physical signal repeater functions between segments.

Field Installation Guidelines

1. Power Supply Wiring: Connect a clean, regulated 24 VDC external power supply to the top terminal blocks. Ensure wire gauge meets standard field wiring requirements and observe strict polarity to prevent power input damage.
2. DIN Rail Mounting: Mount the 1786-RPA securely onto a 35 mm DIN rail in a horizontal or vertical orientation inside an industrial enclosure. Verify ground spring contacts make firm connection with a grounded metal rail.
3. Daughter Module Assembly: Mechanically align and lock expansion modules onto the right-side backplane connector before applying 24 VDC main power. Do not connect or disconnect modules while the backplane is energized.
4. Coaxial BNC Connection: Terminate coaxial cables with standard ControlNet BNC connectors. Maintain proper shield grounding practices at node taps to eliminate high-frequency EMI noise.
5. Backplane Current Calculation: Calculate the sum of backplane current draws for all connected expansion modules to verify total consumption stays strictly below the 1.6 A @ 5 VDC rating.