LinkNet Termination Resistor Woodward MicroNet 9905-760

Product Overview

The Woodward 9905-760 serves as a critical passive component within the MicroNet LinkNet distributed I/O architecture. This termination resistor maintains the electrical balance of the Local Operating Network (LON) by matching the characteristic impedance of the communication line. It effectively absorbs traveling waves at the end of the bus, preventing signal reflections that cause data corruption and communication timeouts between the MicroNet CPU and remote I/O nodes.

Technical Specifications

The 9905-760 provides the precise resistance values required to stabilize LON-based fieldbus topologies.

Engineering Advantages

The 9905-760 addresses fundamental physical-layer challenges in distributed turbine control environments:

• Elimination of Data Jitter: By suppressing voltage reflections on the LON bus, this resistor ensures the CPU receives clean, square-wave signals. This prevents the "ghost faults" and intermittent I/O dropouts that often plague un-terminated networks.

• Extended Network Distance: Proper termination allows the LinkNet bus to reach its maximum rated distance without signal degradation. It enables stable communication for I/O nodes located in remote enclosures far from the main control rack.

• EMI Noise Hardening: In the high-interference environment of power plants, an un-terminated bus acts as an antenna for electromagnetic noise. The 9905-760 closes the loop, significantly reducing the system's susceptibility to ambient EMI.

• Simplified Troubleshooting: Using an official Woodward 9905-760 ensures the resistance values perfectly match the LinkNet transceiver requirements. This removes the guesswork during system commissioning and simplifies the validation of the physical communication layer.

FAQs

• Where exactly should I install the 9905-760 in my network?

  You must install a 9905-760 termination resistor at the two physical ends of each LON bus segment. Placing them in the middle of a run or omitting them at the ends will cause communication errors.

• Can I use a standard commercial resistor instead of the 9905-760?

  While a standard resistor may have the same nominal value, Woodward's 9905-760 is built to industrial tolerances and environmental ratings specifically for turbine control applications. Using generic components introduces potential failure points and may void system certifications.

• What symptoms indicate a failing or missing termination resistor?

  Common symptoms include "LinkNet Timeout" alarms, fluctuating analog input values, and high error counts in the CPU diagnostic logs. If your I/O modules frequently go "offline" and then recover, check the integrity of your 9905-760 terminators.

• Does this part require a "Brand New" purchase for such a simple component?

  Yes. Corroded or aged resistors can develop parasitic inductance or shift in resistance value. A 100% Brand New 9905-760 guarantees the exact impedance matching required for high-speed LON communication, ensuring long-term system stability.