Description
The Woodward 9905-973 is a distributed 8-channel relay output module designed for the LINKnet I/O network architecture. Working in tandem with Woodward NetCon control systems or specialized industrial engine and gas turbine management frameworks, this module offloads non-turbine critical sequencing, peripheral monitoring, and remote programmatic switching from the main CPU processing bus. It converts low-power digital serial or network bus signals into galvanic-isolated electromechanical switch outputs to manage external high-power plant components like solenoids, contactors, and trip circuits.
Technical Specifications
| Parameter | Value |
| Brand / Manufacturer | Woodward |
| Model Number | 9905-973 |
| Product Line | LINKnet Distributed I/O |
| Output Channels | 8 independent electromechanical relay outputs |
| Relay Contact Rating | 5 A at 28 V DC (nominal resistive load) |
| Power Supply Input | 18 V DC to 32 V DC |
| Power Consumption | 5.3 W to 14 W maximum (depending on coil state density) |
| Network-to-I/O Isolation | 277 V AC galvanic isolation |
| Network Interface Style | Single twisted-pair serial trunk communication |
| Max Nodes per Serial Trunk | Up to 60 LINKnet modules |
| Operating Temperature | 0 °C to +55 °C |
| Physical Enclosure | Din-rail mountable Phoenix field termination assembly |
| Diagnostic Indicators | Functional Fault LED and status indicators per channel |
Procurement & Commercial Availability
- Condition: New Surplus (Factory Sealed) or Tested Refurbished. Remanufactured units undergo 100% inductive load relay cycle operations and isolation resistance validation.
- Warranty: 12-month industrial-grade hardware warranty from delivery date.
- Lead Time: Normally ships in 1 to 3 business days for global dispatch from available stock inventory.
- Pricing Notice: Listed pricing is indicative of secondary marketplace baseline parameters. Final transaction quotes vary with component constraints and current global sourcing levels; contact us for a binding quote.
Application Architecture & Field Maintenance Notes
Network Topology and Node Addressing
The 9905-973 interfaces with the host controller via a single twisted-pair wiring network trunk running back to a primary controller interface card. Up to 60 independent LINKnet nodes can inhabit a single trunk loop.
To assign node positions on a replacement module:
- Locate the two integrated rotary switches on the module housing.
- Prior to system hot insertion, dial these hardware switches (01 to 60) to exactly mirror the decimal node address assigned within the application software code.
- Mismatched address switch positions will trigger immediate bus fault timeouts on the host controller.
Scan Rate Execution Bounds
LINKnet architecture prioritizes system isolation and physical distribution over raw execution velocity. The absolute scan rate loop updates as a function of total nodes on a single serial run:
Because typical update times exceed 80 ms, this module must not be integrated into closed-loop high-speed turbine overspeed protection paths or safety critical ESD paths. Limit its implementation to auxiliary valve sequencing, lube oil pump states, and status alarms.
Hot-Swap Field Practices
The 9905-973 supports hot-swappable module replacement without forcing a total system power down. When executing an on-line replacement:
Caution: Verify that the field wiring terminal strip contains no active voltage potentials higher than 28 V DC or 120 V AC. Unclamping live high-inductive relay leads can initiate localized arc flash events, causing terminal track degradation or inductive cross-talk damage inside the adjacent network transceivers.
Frequently Asked Questions
Can this module handle direct 120 V AC loads on its contact terminals?
While the module isolation barriers handle peak dielectric stresses up to 277 V AC, the physical contacts on the basic relay assembly are optimized for DC voltages (5 A at 28 V DC). Running high-current 120 V AC inductive solenoid circuits directly through the module without external suppression components accelerates contact pitting and risks welding the contact points closed. Use an intermediate interposing relay for high-current AC application loads.
How do I troubleshoot a flashing Functional Fault LED on the module face?
A persistent hardware fault status usually indicates a communication dropout or internal processor check failure. First, check the continuity of the twisted-pair network cable shield and verify that maximum trunk line distances do not exceed length limits for the specified ambient temperature range. Next, confirm that the rotary node address match matches the software configuration profile exactly.
Does the 9905-973 require external power, or does it run off the network loop?
The unit demands an external power input ranging from 18 V DC to 32 V DC connected directly to its power input terminals. The internal relay coils draw structural power directly from this auxiliary source rather than drawing down the low-power communications signal loop.
