How Do You Extend ControlNet Beyond Coaxial Limits?
Copper trunk segments degrade over distance. Ground loops and electromagnetic noise corrupt deterministic traffic. Consequently, the Allen-Bradley 1786-RPFRL converts electrical ControlNet signals to optical signals. This fiber ring long-distance repeater belongs to the ControlNet / Bulletin 1786 series. It preserves 5 Mbps scheduled communication across long runs.
1786-RPFRL Key Features and Technical Specifications
- Network speed: Deterministic ControlNet operation at 5 Mbps.
- Fiber interface: Multimode fiber at 820 nm with ST connectors.
- Segment reach: Up to 3 km per segment; ring up to 20 km.
- Optical budget: 15 dB loss limit across the fiber ring.
- Ports: Two BNC coax ports plus two ST fiber ports.
- Power: 24V DC supply drawing 570 mA at 5V DC (3.02 W).
- Isolation: 50V isolation between network domains.
- Environment: Operating range 0-60 C; IP20 enclosure rating.
Notably, the 50V isolation blocks ground-loop currents that would otherwise corrupt coax segments. Meanwhile, the 15 dB loss limit defines exact optical budgeting for each ring.
Where Does the 1786-RPFRL Fit in ControlNet Topologies?
ControlNet networks support up to 99 nodes. Coaxial trunk media uses quad-shielded RG-6 coax (75 ohm) with BNC connectors. The 1786-RPFRL bridges these electrical trunks into redundant fiber rings. Therefore, plants extend control networks across large facilities without sacrificing determinism. For instance, a long conveyor line can span multiple buildings over a fiber ring. Similarly, noisy welding areas benefit from noise-immune optical segments. In both cases, the repeater maintains scheduled 5 Mbps traffic.
Integration and Compatibility Notes
The module presents two BNC coax ports and two ST fiber ports. It regenerates and extends ControlNet media alongside other Bulletin 1786 repeaters and adapters. When wiring into fieldbus networks, an external gateway or connection module may be required. Confirm exact cables and gateways with the supplier before installation.
Lifecycle Status and Availability
The 1786-RPFRL is discontinued as of 2022-09-30. Rockwell Automation recommends an engineering replacement, migrating to the 1786-RPFRXL or comparable ControlNet fiber ring alternatives. Please verify current lifecycle status and availability with AutoDCSTech before ordering.
Product Support and Availability
AutoDCSTech supplies the 1786-RPFRL and related ControlNet fiber ring components. Contact AutoDCSTech with your exact requirements for precise matching.
