Agilent 44474A card with 44474A Connector Terminal Relay Block .

The Agilent 44474A Digital I/O Module, paired with the 44474A Connector Terminal Relay Block, provides 16 bi-directional data lines and 4 control/handshaking lines for signal routing in data acquisition and automated test systems. The module supports flexible addressing - individual bit selection, two independent 8-bit ports, or a single 16-bit word - enabling simultaneous input and output operations. TTL-compatible inputs and open-collector outputs deliver 0.125 A current sink capability per I/O line.

The 44474A integrates into Agilent 3499A/B/C mainframes and the 3488A Switch/Control Unit (Option 014), making it suitable for high-density switching platforms and bench test configurations.

Technical Specifications

Data Lines:

• 16 bi-directional lines with TTL input compatibility and open-collector output


• Output voltage (high): >2.4 V @ I <8 mA


• Output voltage (low): <0.4 V @ I 2.0 V


• Input voltage (low): <0.8 V


• Maximum line-to-chassis voltage: +30 V DC


• Current sink capability: Up to 0.125 A at Vout 2.4 V @ I <400 µA


• Output voltage (low): <0.5 V @ I 2.0 V


• Input voltage (low): <0.8 V


• Maximum line-to-chassis voltage: +5 V DC

Key Features

• Three addressing modes: individual bits, dual 8-bit ports, or single 16-bit word


• Simultaneous input and output operation capability


• TTL-level signal compatibility


• 44474A Connector Terminal Relay Block: 8 × 3 × 2 in, 0.5 lbs

Typical Applications

• Automated test equipment and bench configurations


• High-density switching platforms requiring flexible signal routing


• General-purpose digital control and monitoring in data acquisition systems

Compatibility & Integration Designed for Agilent 3499A/B/C mainframes and available as Option 014 for the 3488A Switch/Control Unit. Note: This product is obsolete per manufacturer designation; availability through third-party suppliers.