Description
Product Overview
The Woodward 9905-973 is an eight-channel discrete output module in the LINKnet distributed I/O family. Its function is to convert control commands transmitted over the LINKnet network into relay switching signals for external equipment. In a turbine or engine control installation, these outputs can be assigned to discrete functions such as solenoid commands, auxiliary equipment control, alarm circuits, and other on/off operations defined by the application. The module provides eight relay output channels, allowing multiple field circuits to be controlled through one distributed I/O node.
The 9905-973 is part of the legacy Woodward LINKnet I/O range. Woodward documentation lists it as the eight-channel relay output module, alongside related nodes for discrete inputs, analog inputs, analog outputs, RTD inputs, and thermocouple inputs. The published product information identifies an 18–32 VDC supply range. Individual unit listings also show relay contact ratings of 5 A at 28 VDC and 500 mA at 115 VAC, 60 Hz. These ratings must be checked against the applicable hardware revision and load characteristics before being used for circuit design. Resistive and inductive loads do not impose the same contact stress, and external suppression may be necessary for inductive loads.
The Woodward 9905-973 should be treated as a networked output node, not as a generic eight-relay replacement board. Correct operation depends on the LINKnet host controller, network addressing, node configuration, output mapping, and field wiring. The relay contact arrangement and actual electrical ratings should be verified from the unit’s revision-specific documentation. This is particularly important when replacing an older installed module: a matching part number does not confirm that the contacts are still within service limits or that the replacement has the same hardware revision. Check all eight channels under controlled test conditions before returning the system to service.
Product Introduction
When a distributed control system loses a relay output node, several field commands may become unavailable even though the main controller remains operational. The Woodward 9905-973 provides eight discrete relay outputs through the LINKnet architecture, supporting separate switching functions from a single I/O module.
For replacement work, the main checks are relay contact condition, revision identification, 18–32 VDC supply compatibility, and correct LINKnet node configuration. Verify the load type and contact rating for every connected circuit before commissioning.
Key Technical Specifications
| Parameter | Specification |
|---|---|
| Product model | 9905-973 |
| Manufacturer | Woodward |
| Product family | LINKnet |
| Product type | Discrete relay output module |
| Output channels | 8 |
| Output function | Relay-based discrete switching |
| Supply voltage | 18–32 VDC |
| Relay contact rating | 5 A at 28 VDC |
| AC contact rating | 500 mA at 115 VAC, 60 Hz |
| Network | Woodward LINKnet |
| Front-panel features | Reset button and fault LED, as reported in product listings |
| Hazardous-location information | Class I, Division 2, Groups A, B, C, D, reported on certain unit revisions |
| Temperature code | T4A, maximum ambient 55°C, reported for Revision K |
| Power consumption | 9.2 W, reported for Revision K |
Specification caution: Published listings show conflicting contact ratings and power-consumption figures for this model. The values above are tied to specific unit descriptions, not a universal rating for every revision. Confirm the nameplate, revision, contact diagram, and Woodward documentation before connecting field loads.
9905-973
Related Products
These modules are part of the Woodward LINKnet distributed I/O family. They provide different signal functions and are not direct substitutes for the 9905-973.
- 9905-971 – 16-channel discrete input module for collecting field contact states.
- 9905-972 – Six-channel 4–20 mA analog output module for transmitting analog control signals.
- 9905-968 – Six-channel 4–20 mA analog input module for process measurement acquisition.
- 9905-969 – Six-channel 4–20 mA analog input module with 24 VDC loop-power capability.
- 9905-970 – Six-channel 100-ohm RTD input module for temperature measurement.
- 9905-966 – LINKnet thermocouple input module with fail-high behavior.
- 9905-967 – LINKnet thermocouple input module with fail-low behavior.
These model functions are identified in Woodward LINKnet system documentation. Check the controller’s supported node configuration before adding or replacing any module.
Frequently Asked Questions
Q1: What is the Woodward 9905-973 used for?
The 9905-973 is an eight-channel LINKnet discrete relay output module. It receives output commands from a compatible Woodward control system and operates relay contacts connected to external circuits. Typical applications include discrete equipment commands, alarm signaling, and auxiliary control functions. The actual assignments depend on the installed control application.
Q2: Can I hot-swap the 9905-973 while the controller is running?
Do not assume live replacement is supported. The available references do not establish a universal hot-swap procedure for this module. Review the applicable LINKnet installation manual and the machine’s maintenance procedure. Determine which field outputs will be affected before disconnecting the node, especially if any outputs participate in protective or shutdown functions.
Q3: Does the 9905-973 support firmware v3.1?
A general firmware v3.1 compatibility statement is not established by the available hardware references. Compatibility depends on the LINKnet host controller, node configuration, and application software revision. Confirm the supported module and software combination using the relevant Woodward documentation.
Q4: Can the 9905-973 switch both AC and DC loads?
Published unit listings identify DC and AC contact ratings, but the permissible load depends on the exact hardware revision and load characteristics. Do not apply the DC rating to an AC circuit or assume that the maximum current is identical for resistive and inductive loads. Check the contact diagram and manufacturer’s rating for the actual unit before wiring it.
Q5: Can I replace the 9905-973 with another eight-channel relay module?
Not solely because the channel count matches. The replacement must also match the LINKnet communication architecture, controller support, node addressing, contact arrangement, electrical ratings, and application configuration. A generic eight-relay module does not provide the same network interface or control-system behavior.
Q6: Will replacing the 9905-973 erase the control-system logic?
The 9905-973 is a distributed output module, not the primary storage location for the controller’s application logic. Replacing the module does not, by itself, mean the main controller program will be erased. However, node addressing, output mapping, configuration data, and field wiring must be checked. Back up the control-system configuration and verify all eight output functions after replacement.
Q7: What should I check when buying a new-surplus or refurbished 9905-973?
Request photographs of the actual module, including its nameplate, revision marking, connectors, and terminal areas. Check for corrosion, damaged contacts, signs of overheating, and previous repairs. For a refurbished unit, request evidence of all eight relay channels operating under suitable test loads, along with network communication and fault-indicator checks. A power-on test alone is insufficient to establish relay contact performance.
Engineering procurement note: The most important issue with the 9905-973 is revision-specific relay performance. Before approving a replacement, match the hardware revision and verify every contact rating against the actual field load. A module that communicates correctly can still be unsuitable for a particular actuator, solenoid, or alarm circuit if its contact ratings do not match the application.
