Agilent/Keysight 34901A

The Keysight 34901A is a general-purpose multiplexer module engineered for the 34970A and 34972A Data Acquisition/Switch Units. It has 20 primary signal channels plus 2 fused current inputs, delivering flexible multi-function signal routing at 60 channels per second. The module supports mixed two-wire and four-wire scanning configurations on a single card, enabling simultaneous measurement of voltage, current, resistance, frequency, and temperature sensors without external shunts.

Technical Specifications

• Channels: 20 multiplexed signal channels + 2 fused current inputs (1 A AC/DC)


• Scan Rate: 60 channels/second


• Switching Voltage: Up to 300 V DC/AC


• Bandwidth: 10 MHz


• Scanning Modes: Two-wire and four-wire (mixed on same module)


• Switching: Break-before-make


• Module Slots: Single slot in 34970A/34972A mainframe


• Weight: 2.095 lbs

Key Features

• Built-in thermocouple reference junction eliminates external compensation


• 4-wire resistance measurement capability for precision low-resistance testing


• Direct current measurement via fused inputs without external shunt resistors


• Integrated multiplexing accommodates voltage, current, frequency, and resistance measurements on the same scan list


• Supports thermocouples, thermistors, and RTDs for temperature monitoring

Typical Applications

• Automated test and measurement systems


• Industrial automation data collection


• Laboratory research and sensor integration


• Multi-channel data logging with mixed sensor types

Compatibility & Integration The 34901A integrates exclusively with Keysight 34970A and 34972A mainframes, occupying one of three available module slots. The host unIt has the digital multimeter engine and system control. The DAQ970A series uses incompatible newer modules and does not support the 34901A.