Agilent/HP 44474A Rev B 16-Bit Digital I/O Module Card Board 44474-66501

The Agilent/HP 44474A Rev B is a 16-bit digital I/O module card for the 3499A/B/C mainframe family, delivering flexible data acquisition and control in industrial and laboratory environments. It has 16 bi-directional data lines plus 4 control/handshaking lines with independent addressing by individual bits, 8-bit ports, or 16-bit word. Each I/O line sinks up to 0.125 A from external devices, making it suitable for direct interfacing with industrial logic and sensor networks.

Technical Specifications

• Digital I/O Lines: 16 bi-directional with individual, 8-bit port, or 16-bit word addressing


• Control/Handshaking Lines: 4 dedicated lines


• Input Levels (TTL): Vin (high) > 2.0 V; Vin (low) 2.4 V @ I < 8 mA; Vout (low) < 0.4 V @ I 2.4 V @ I < 400 µA; Vout (low) < 0.5 V @ I < 2 mA


• Current Sink Capability: Up to 0.125 A from external devices at Vout < 1.25 V


• Maximum Line Voltage (Digital I/O): +30 V DC


• Maximum Line Voltage (Handshake): +5 V DC


• Connector: Screw terminals included; optional HP 44484A terminal block

Key Features

• TTL-compatible input and open-collector output architecture


• Flexible addressing - select individual bits, dual 8-bit ports in mixed I/O mode, or single 16-bit word


• High current sink capability enables direct control of relays, solenoids, and indicator lamps


• Independent port configuration supports simultaneous input and output operations


• Accommodates ±30 V transients on digital lines for industrial noise immunity

Typical Applications

• Automated test equipment (ATE) with distributed I/O control


• Sensor and switch interfacing in data acquisition systems


• Relay and solenoid driving in laboratory automation


• Mixed-signal control systems requiring independent input/output channels

Compatibility & Integration Installs directly into Agilent/HP 3499A, 3499B, and 3499C mainframes. User's Manual, Service Manual, and Quick Reference Guide for the 3499A/B/C platform available.