Woodward 9905-968

Technical Dossier

Product Details And Specifications

Woodward 9905 Series Technical Notes

The Woodward 9905 Series represents a core family of I/O and control modules deployed extensively across global heavy industry, including petrochemical refineries, nuclear power stations, offshore platforms, and large-scale thermal generation facilities. Woodward, headquartered in Fort Collins, Colorado, USA, has supplied turbine and engine control systems for over a century. The 9905 Series modules serve as the primary I/O backbone within Woodward's MicroNet, NetCon, and 505 governor control architectures. Their ruggedized design, wide operating temperature tolerance, and deterministic scan cycle make them a standard specification in long-lifecycle plant environments where control system replacement is cost-prohibitive. Installed base density is highest in North America, Europe, and the Middle East, with significant representation in LNG terminals and combined-cycle power plants.

The Evolution of 9905 Series Architecture

The 9905 Series was introduced as part of Woodward's transition from discrete relay-based governor controls to fully digital, microprocessor-driven turbine management. Early modules in the series interfaced with Woodward's analog governor platforms and used parallel backplane communication. As the MicroNet platform matured through the 1990s and 2000s, the 9905 Series was extended to support higher-density I/O, redundant power architectures, and serial fieldbus integration. Key architectural milestones include the introduction of isolated analog input channels (reducing ground loop interference in high-noise plant environments), the shift to 24 VDC logic power standards, and the addition of HART-compatible signal conditioning on select analog input variants. Compatibility between early and late 9905 revisions is generally maintained at the backplane connector level, but firmware dependencies on the host CPU module must be verified before substitution. Modules produced after approximately 2005 carry revised conformal coating specifications for improved humidity resistance. The series is now in a mature-to-end-of-life phase; Woodward has transitioned new designs to the MicroNet Plus and MicroNet TMR platforms, but the 9905 Series remains in active service at thousands of installed sites globally, creating sustained demand for spare and replacement modules.

9905 Series Full Catalog & Functionalities (SKU List)

The following SKUs represent verified, commonly referenced modules within the Woodward 9905 Series. Modules are classified by primary function:

Analog Input Modules

• 9905-968: 6-channel analog input module; 4–20 mA / 0–10 V configurable per channel; used in turbine speed and process variable acquisition.
• 9905-969: 8-channel analog input module; extended channel count variant for high-density sensor integration.
• 9905-976: Isolated analog input module; per-channel galvanic isolation for high-noise refinery environments.
• 9905-977: Thermocouple input module; supports J, K, T, E type thermocouples; used in exhaust gas temperature monitoring.

Analog Output Modules

• 9905-970: 6-channel analog output module; 4–20 mA output; drives actuators and positioners in governor control loops.
• 9905-971: 4-channel high-current analog output; supports valve actuator loads up to 50 mA per channel.

Digital Input Modules

• 9905-972: 16-channel digital input module; 24 VDC logic; used for discrete status and permissive signal acquisition.
• 9905-973: 32-channel digital input module; high-density DI for large turbine train monitoring.
• 9905-978: Isolated digital input module; optically isolated channels for high-voltage field signal interfaces.

Digital Output Modules

• 9905-974: 16-channel digital output module; relay and transistor output options; drives solenoids and alarm annunciators.
• 9905-975: 8-channel relay output module; rated for 2A per channel; used in trip and shutdown logic.

CPU / Controller Modules

• 9905-001: MicroNet main processor module; hosts control application and manages backplane I/O scan.
• 9905-002: Redundant CPU module; hot-standby configuration for critical turbine applications.
• 9905-458: Application-specific controller module; pre-configured for steam turbine governor functions.

Communication & Power Modules

• 9905-980: Modbus RTU communication adapter; RS-485 interface for DCS integration.
• 9905-981: Ethernet communication module; supports Modbus TCP for modern SCADA connectivity.
• 9905-985: 24 VDC power supply module; redundant-capable; provides backplane and field power.
• 9905-986: Redundant power supply module; automatic failover; used in continuous-duty applications.

Quality Control for the 9905 Series Range

The 9905 Series modules incorporate multi-layer PCBs with proprietary backplane bus connectors that require specialized handling and test procedures. DriveKNMS applies the following quality control protocol to all 9905 Series units processed through our facility: