Allen-Bradley 1786-RPFRXL/B ControlNet Fiber Ring Extra-Long Distance Repeater

Allen-Bradley 1786-RPFRXL/B ControlNet Fiber Ring Extra-Long Distance Repeater

Configured for signal regeneration and network extension in ControlNet platforms, the Allen-Bradley 1786-RPFRXL/B (1786-RPFRXL/B Fiber Optic Repeater Module) provides direct physical/electrical execution. It retimes and transmits deterministic 5 Mbps data streams across single-mode or multi-mode fiber optic cable runs. The module eliminates ground potential differences and guarantees high electromagnetic immunity across extended network segments without introducing transmission jitter or frame degradation.

Hardware Specifications

Deterministic Network Isolation & Determinism

The 1786-RPFRXL/B module integrates dedicated backplane bus communication velocity processing with optical signal re-clocking to enforce determinism across ControlNet ring topologies. By converting electrical coaxial frames into 1310 nm optical pulses, the unit insulates sensitive controller hardware from high-voltage transients and industrial noise. Signal propagation delays remain fixed, maintaining strict scheduled and unscheduled I/O density scaling and network time-slot synchronization across 20 km fiber segments. Firmware flash compatibility ensures seamless optical media conversion without requiring modifications to the controller scan list or network configuration software.

Frequently Asked Questions

Q: What is the optical budget limitation when deploying the module on single-mode versus multi-mode fiber?

A: The module supports a maximum physical distance of 20 km using 9/125 um single-mode fiber at a 1310 nm wavelength. When attached to 62.5/125 um multi-mode fiber infrastructure, the maximum allowable distance is restricted to 3 km due to modal dispersion limitations at 5 Mbps.

Q: How does the internal relay output function during power loss or link degradation?

A: The fault relay contacts (rated for 900 mA at 30 VDC) change state when 5 VDC power drops below operational thresholds or when optical link loss is detected on either channel. This provides a hardware fault contact for external alarm circuits or PLC digital input monitoring.

Q: Can this repeater module be hot-swapped into an energized repeater adapter base?

A: Removal and insertion under power (RIUP) is permissible only if the surrounding atmosphere is free of flammable gas concentrations. In ATEX Zone 2 installations, power to the rack base must be removed prior to pulling or seating the module to avoid spark hazards on the backplane interface.

Field Installation Guidelines

Mount the 1786-RPFRXL/B onto the dedicated 1786 repeater adapter rack on standard DIN rail. Ensure the DIN rail is grounded directly to the central panel enclosure earth bus using a short, heavy-gauge copper strap (minimum 8 AWG) to maintain 50 V continuous isolation protection.

When terminating fiber optic links, clean all ST connectors with lint-free optical wipes and isopropyl alcohol prior to insertion. Observe the minimum bend radius specifications for single-mode fiber (typically 10 times the outer cable diameter) to avoid micro-bend attenuation. Tighten all screw terminal copper wiring (22 to 14 AWG) to a torque rating of 0.6 to 0.8 Nm. Maintain separation between optical fiber runs and high-voltage AC power cabling inside wire ducts to prevent physical cable damage.