Agilent / Keysight 34950A 64-bit Digital I/O with Memory and Counter for 34980A

The Keysight 34950A is a 64-bit Digital I/O module for the 34980A Multifunction Switch/Measure Unit, delivering bidirectional digital control, pattern generation and capture, and frequency measurement in a single slot card. Organized into two independent banks of four 8-bit channels each, the module supports programmable polarity, variable input thresholds from 0 V to 5 V, and source/sink drive current up to 24 mA per channel. Each bank includes 64 KB of volatile memory for buffered pattern operations at digital speeds up to 10 MHz, with synchronous handshake control across three dedicated lines per 32-bit bank.

The integrated counter/totalizer provides two independent 10 MHz measurement channels for frequency, period, duty cycle, and pulse width analysis, plus a programmable 20 MHz divide-by-n clock output for test synchronization. Grouped I/O operations support 16- and 32-bit data widths. Standard 78-pin D-sub connectors interface directly to the 34980A mainframe, enabling seamless integration into automated test and data acquisition systems with LAN, USB, and GPIB connectivity.

Technical Specifications

• Digital I/O: 64 bidirectional bits organized as two banks; Bank 1 (channels 101–104) and Bank 2 (channels 201–204), each containing four 8-bit channels


• I/O Configuration: Programmable polarity per channel; input thresholds 0 V to 5 V; output level programming; 24 mA source/sink current per channel


• Data Grouping: 16-bit and 32-bit channel operations supported


• Memory: 64 KB volatile per bank; pattern capture and generation to 10 MHz


• Handshaking: Synchronous (strobe) mode; three handshake lines (H0, H1, H2) per 32-bit bank


• Counter/Totalizer: Two channels (301, 302) at 10 MHz maximum; totalizer and initiated measurement modes for frequency, period, duty cycle, and pulse width


• Clock Output: Programmable 20 MHz divide-by-n clock


• Connectors: 78-pin D-sub

Key Features

• Dual independent memory banks enable simultaneous pattern generation and capture


• Configurable handshake protocols support buffered I/O with hardware strobing


• Flexible threshold and polarity settings adapt to mixed-signal test requirements


• Counter channels integrate directly into 34980A scan lists for continuous monitoring

Typical Applications

• Automated test equipment (ATE) digital stimulus and response capture


• Pattern-based device functional testing


• Real-time event counting and frequency measurement


• Multi-channel synchronous control in data acquisition systems

Compatibility & Integration The 34950A slots into the 34980A mainframe, inheriting its LAN, USB, and GPIB connectivity. Digital input and counter channels integrate into 34980A scan lists for automated measurement sequencing.