Order now 1786-TNCLXT4 to maximize space efficiency and signal clarity in your ControlNet repeater racks. The Allen-Bradley 1786-TNCLXT4 is a specialized, extra-short coaxial interconnect cable assembly designed for linking adjacent ControlNet modules, particularly within a 1786 modular repeater system (1786-RPA/RPCD). With a precision length of approximately 4 inches, this cable eliminates the «nest» of excess wiring often found in control cabinets, significantly reducing the potential for electromagnetic interference (EMI) pick-up. Factory-terminated with high-grade 75-ohm BNC connectors, the 1786-TNCLXT4 ensures a low-loss, high-integrity connection between redundant media ports or between repeater segments. By using this genuine Rockwell Automation accessory, you maintain the strict impedance matching required for 5 Mbps deterministic communication, preventing the packet retries and network jitter associated with hand-made or low-quality patch cables.
What Is the 1786-TNCLXT4?
The 1786-TNCLXT4 is a «jumper» or «interconnect» cable. Its primary function is to facilitate the connection between ControlNet ports that are physically close to one another, such as when daisy-chaining redundant trunks A and B on a modular repeater base. Because the cable is factory-crimped, it provides a gas-tight seal at the BNC interface, which is critical for preventing oxidation in humid or corrosive industrial environments. This short-run media is a vital component for technicians looking to certify their network to OEM standards, as it provides a predictable and tested propagation delay, ensuring the network update time (NUT) remains within calculated tolerances.
Key Technical Specifications
- Part Number: 1786-TNCLXT4
- Manufacturer: Allen-Bradley / Rockwell Automation
- Cable Length: 4 inches (approx. 10 cm)
- Impedance: 75 Ohms precision matched
- Connectors: Dual Male BNC (factory terminated)
- Shielding: Quad-shielded RG-6 compliant
- Application: Module-to-module interconnect / Repeater link
- Jacket Material: Industrial PVC
Architecture and Redundancy Applications
In high-availability ControlNet systems, redundancy is achieved by running two parallel trunks (A and B). The 1786-TNCLXT4 is often used to connect the «Link» ports on 1786-RPCD modules to ensure that both sides of the repeater system are perfectly synchronized. Its short length is not just about aesthetics; it is an engineering choice to minimize the cumulative signal attenuation that occurs when using longer, unnecessary patch leads. This cable is the standard for compact, professional-grade ControlNet rack builds.
Installation Advice
When installing the 1786-TNCLXT4, ensure that the BNC connectors are fully seated and clicked into the locked position. Because the cable is so short, it can exert more mechanical stress on the module’s BNC jack if it is twisted or pulled at an unnatural angle. Before locking, rotate the cable to a position where it sits naturally between the two ports. This prevents «connector creep» and ensures that vibration from nearby machinery does not cause the center pin to lose contact. Expert tip: periodically inspect the gold-plated center pins of the cable for any signs of misalignment before insertion to avoid damaging the internal female sockets of your expensive repeater modules.
Frequently Asked Questions
Q: Can I use this for connecting a PLC to a Tap?
A: While electrically possible, the 4-inch length is usually too short for a standard tap-to-processor connection. For that application, a longer drop cable like the 1786-TNCL10 or 1786-CP is recommended.
Q: Does this cable support the 5 Mbps ControlNet speed?
A: Yes, it is fully rated for the standard 5 Mbps ControlNet data rate and is designed to maintain the deterministic timing required for PLC-to-I/O communications.
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