5438-861 - 12-channel TMR Analog Output Module

TECHNICAL SPECIFICATIONS:

Part Number: 5438-861
Manufacturer: Woodward
Series: MicroNet TMR (Triple Modular Redundant)
Module Type: Analog Output (AO)
Channels: 12 Channels
Output Signal: 4–20 mA
Architecture: 2-out-of-3 (2oo3) Voting Logic
Max Load Resistance: 600 Ohms @ 20 mA
Isolation: 500 Vdc
Operating Temperature: -30 °C to +65 °C
Availability: In Stock
Origin: United States

FUNCTIONAL DESCRIPTION:

The 5438-861 is a high-integrity 12-Channel TMR Analog Output Module designed and manufactured for the Woodward MicroNet TMR systems. It acts as the final control interface, changing digital commands from the system's redundant processors into precise 4–20 mA signals. This module is used for mission-critical turbine applications where a single point of failure cannot be allowed, ensuring that fuel valves, actuators, and positioners receive correct commands even if hardware issues occur.

TRIPLE MODULAR REDUNDANCY & VOTING DYNAMICS:

The 12-channel TMR Analog Output Module works within a triplicated control environment to provide high system availability. By connecting to the TMR backplane, the module receives three separate data streams from the R, S, and T processors. It uses a hardware-level current-summing setup to vote on these signals in real-time. Through this 2-out-of-3 (2oo3) fault tolerance logic, the module finds the correct output by comparing the three inputs. If one internal driver path fails or shows a difference, the hardware automatically ignores and isolates it, keeping a steady signal to the field device without any jumps or glitches in the output current.

SIGNAL INTEGRITY & HIGH-VOLTAGE ISOLATION:

To keep the operation stable in noisy industrial areas, the module includes protection features for high-precision control. It provides 500 Vdc of galvanic isolation between the field wiring and the internal control backplane. This creates a barrier that protects central processors from transients, surges, and ground loops. Also, 12-bit Digital-to-Analog (D/A) converters keep the 4–20 mA signals precise across the full industrial temperature range. The module can drive loads up to 600 Ohms, which allows for long cable runs and high-impedance actuator coils without signal loss or saturation.

DIAGNOSTICS & FAULT ISOLATION:

The 12-channel TMR Analog Output Module has self-diagnostic features that monitor the health of the control loop. Through loop read-back, the module senses the actual current flowing in each output loop. Any difference from the commanded value, whether from internal part failure or wiring faults, is flagged as a channel fault. If a failure is found in a driver path, the fault isolation logic removes the failed part, letting the healthy paths keep full control. For physical protection, the unit has safeguards against overcurrent and short-circuit conditions, while the passive-convection design keeps the 12 channels thermally stable during high-load use.

WIRING & CHASSIS INTERCONNECTIVITY:

The module is made for fast installation and high-availability maintenance. It is usually paired with a TMR Analog Output Terminal Board (AOTB) using high-density shielded cables to keep field wiring organized and reduce signal interference. Inside the chassis, the module is fully hot-swappable. In a redundant MicroNet TMR setup, this lets maintenance teams replace a faulty 5438-861 module while the system is live and the turbine is running. This reduces repair time and ensures that critical functions are not stopped during service.

WHY BUY FROM WOC:

World of Controls supports Woodward TMR setups by offering the 5438-861 in both UNUSED and REBUILT conditions to meet your specific budget and project timelines. Our commitment to quality means every unit goes through strict validation on specialized TMR test racks to check voting logic accuracy and high-load performance. We maintain a large inventory of legacy and current Woodward parts, providing a reliable supply chain for aging control systems. With our global shipping network and 24/7 technical support, we help you get the hardware and expert guidance needed to keep your critical control systems running without downtime. Whether you need a quick replacement or a spare for your inventory, we provide a dependable alternative to traditional lead times.

FREQUENTLY ASKED QUESTIONS:

What is the Woodward 5438-861?

It is a 12-channel Analog Output Module designed for use within the Woodward MicroNet TMR system. It is a critical interface component that receives commands from triplicated processors and produces twelve independent 4-20 mA signals to drive fuel valves and actuators in mission-critical turbine applications.

How does the module keep the signal steady during a 2-out-of-3 (2oo3) voter switch?

The 5438-861 uses a high-speed hardware current-summing setup. When internal diagnostics find a failure in one of the three redundant paths, the failed path is isolated. The other two paths adjust their output to keep the total current correct. This happens within the 5 ms update cycle, so there are no glitches in the signal sent to the field actuator.

What happens if the load resistance is too high?

The module drives a maximum load of 600 Ohms at 20 mA. If the loop resistance goes above this due to long cables or high-impedance coils, the module might hit a voltage limit. This prevents it from reaching the full current. The internal read-back monitors this and triggers a Channel Fault if the current is not correct.

How does the 5438-861 handle heat during high-current use?

Running all 12 channels at 20 mA creates heat. The module uses a passive-convection design and the MicroNet TMR chassis airflow to move heat away. Internal sensors monitor the temperature. If it gets too high, the module reports an alarm so the user can fix the cooling before a shutdown occurs.