Keysight / Agilent / HP 44425A 16-Channel Isolated Digital Input/Interrupt

The Keysight 44425A is a 16-channel isolated digital input/interrupt module engineered for data acquisition systems requiring signal isolation and event-driven control. It provides optically isolated inputs across 16 channels, with the first 8 channels capable of generating interrupts to trigger immediate system response. The module accepts 5, 12, or 24 Vdc inputs and includes an on-board 5 V supply for driving external contact closures and open collector outputs.

– Technical Specifications

• 16 isolated digital input channels
• First 8 channels support interrupt generation
• Input voltage compatibility: 5, 12, or 24 Vdc
• On-board 5 V external drive supply with 9.4 kΩ effective pull-up resistance
• Optical isolation on all inputs
• Fully programmable functions and channel masks

– Key Features

The module operates in two primary modes. Digital input mode monitors all 16 channels for signals such as limit switches, position indicators, and digital data buses. Interrupt mode leverages channels 0–7 to detect transient signals and level changes, enabling the connected controller to halt normal execution and invoke pre-programmed event handlers. This dual-mode architecture supports both continuous monitoring and real-time event capture without requiring constant polling.

Optical isolation prevents signal interference and enhances system reliability in noisy industrial environments. All input thresholds and interrupt masks are programmable, allowing flexible configuration without hardware modification.

– Typical Applications

Designed for industrial automation, process monitoring, and supervisory control systems. Ideal for applications requiring isolated digital sensing of discrete events, momentary switch closures, status indicators, and asynchronous alarm conditions.

– Compatibility & Integration

The 44425A integrates directly with the Keysight/Agilent/HP 3497A Data Acquisition System. It can be combined with the Actuator/Digital Output Assembly (Option 110) to establish a complete isolated digital input/output port within the 3497A chassis.