Purchase now 1786-RG6 to establish a rock-solid physical foundation for your industrial ControlNet communication network. The Allen-Bradley 1786-RG6 is a high-performance, quad-shielded coaxial trunk cable specifically engineered to meet the stringent deterministic requirements of Rockwell Automation systems. Unlike standard commercial RG-6 cables, this industrial-grade media is designed to maintain a precise 75-ohm impedance over long distances, which is critical for the 5 Mbps Manchester-encoded data transmission used in ControlNet. The quad-shielding architecture—comprising multiple layers of foil and braid—provides exceptional immunity against the electromagnetic interference (EMI) and radio frequency interference (RFI) typically found in heavy manufacturing environments near variable frequency drives and high-voltage motors. By utilizing this genuine OEM trunk cable, facilities can ensure maximum signal integrity, minimize packet retries, and guarantee the long-term reliability of their PLC-to-PLC and PLC-to-I/O communications across the plant floor.
What Is the 1786-RG6?
The 1786-RG6 is the primary medium used to build the ControlNet trunk line. It serves as the main «backbone» of the network to which individual nodes are connected via taps (1786-TPS). This cable is designed for fixed installations in cable trays or conduits and is built to withstand the rigors of industrial automation. Because ControlNet is a time-scheduled network, the physical geometry and electrical characteristics of the 1786-RG6 are vital. Any deviation in the cable’s construction could lead to signal reflections and timing jitter, which can cause intermittent network dropouts. The 1786-RG6 ensures that every data pulse is delivered with the precision required for high-speed industrial control.
Key Technical Specifications
- Part Number: 1786-RG6
- Manufacturer: Allen-Bradley / Rockwell Automation
- Cable Type: RG-6 Coaxial (Quad-shielded)
- Impedance: 75 Ohms +/- 3 Ohms
- Velocity of Propagation: 82% (Nominal)
- Outer Diameter: 7.57 mm (0.298 in)
- Shielding: Two layers of aluminum foil and two layers of aluminum braid
- Jacket Material: Polyvinyl Chloride (PVC)
- Operating Temperature: -30 to +75 Celsius (-22 to +167 Fahrenheit)
ControlNet Media Architecture
ControlNet is a robust fieldbus that uses a trunk-line/drop-line topology. The 1786-RG6 forms the trunk-line segments between taps. To maintain network health, segments are terminated with 75-ohm resistors (1786-XT) at each physical end. The 1786-RG6 supports distances up to 1000 meters without repeaters, depending on the number of taps connected. This industrial media is the standard for legacy and modern ControlNet installations where uptime is non-negotiable.
Installation Advice
When installing the 1786-RG6, the minimum bend radius is the most critical factor to protect the cable’s internal geometry. For a standard PVC jacket, the minimum bend radius is 76 mm (3 inches). Exceeding this limit can deform the dielectric material and change the cable’s local impedance, leading to signal «standing waves» that degrade network performance. Additionally, always use the 1786-CTK tool kit for stripping and crimping BNC connectors. Using non-specified tools can damage the quad-shielding layers, significantly reducing the cable’s EMI immunity and potentially leading to intermittent communication errors in high-noise areas.
Frequently Asked Questions
Q: Can I use standard CATV RG-6 cable instead of the 1786-RG6?
A: No. While they share a name, the 1786-RG6 has specific quad-shielding and dielectric requirements for 5 Mbps industrial data. Standard TV cable often lacks the necessary shielding density or impedance consistency for deterministic industrial protocols.
Q: Is the 1786-RG6 suitable for high-flex applications like cable tracks?
A: No, the 1786-RG6 is intended for fixed installation. For applications requiring continuous movement or high-flex, you should specify the 1786-RG6F (Flex) version, which features a more pliable jacket and stranded center conductor.
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