Product Overview
When fault tolerance is critical in your control system, the Woodward 9905-971 Discrete Input Module provides robust monitoring and detection capabilities. Designed for industrial automation, this module supports 24 discrete input channels and integrates latent fault detection to prevent undetected relay failures. Each input operates at 24 Vdc, and the module’s series-parallel relay configuration ensures that a single relay failure does not compromise output integrity.
Technical Specifications
The Woodward 9905-971 delivers reliable performance with the following key parameters:
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Number of channels: 24
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Update time: 5 ms
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Time stamping resolution: 1 ms
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Input voltage: 24 Vdc
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Country of manufacture: United States
Each channel detects input states with 1 ms timestamp accuracy, making the 9905-971 suitable for high-speed event recording.
Industry Applications
The Woodward 9905-971 is ideal for turbine control, gas compression, and power generation systems where fault tolerance is paramount. In a gas turbine supervisory system, latent fault detection ensures that a single relay failure does not cause an unexpected shutdown. For emergency shut‑down circuits, the module’s ability to detect relay failures without affecting output state improves overall system reliability.
Installation & Setup Guidance
Install the Woodward 9905-971 by inserting it into the control chassis card guides and securing it with the top and bottom screws. Two handles allow easy disengagement from the motherboard. When using internal 24 Vdc contact wetting, install jumpers between terminals 33, 34, and 35. If an external 18–32 Vdc or 100–150 Vdc source is used, connect its common to terminals 34 and 35. Ensure all discrete inputs share a common reference point with the contact power source.
Maintenance & Reliability
The Woodward 9905-971 uses latent fault detection to periodically test relay contacts without disrupting operation. This routine self‑testing—opening and closing relays in pairs—detects stuck or failed contacts early. For maximum reliability, inspect the module during scheduled maintenance and verify that readback circuitry reports no errors. The 9905-971’s series‑parallel relay design means that even if two relays fail, the output remains in the correct state.
Selection Guide & Purchasing Advice
Before purchasing a Woodward 9905-971, verify that your system’s chassis supports 24‑channel discrete input modules and that the contact wetting voltage matches your supply (24 Vdc internal or external 18–32 Vdc / 100–150 Vdc). Confirm the required number of modules per controller (the control accepts four modules, each handling six contact inputs). For reliable supply and rapid support, choose a trusted distributor like PLC Source PRO (available at ubest101.myshopify.com). The 9905-971 is in stock with a typical repair turnaround of 3–7 days.