Agilent/Keysight 34921T

The Keysight 34921T is a detachable terminal block accessory engineered for discrete signal wiring to the Keysight 34921A and L4421A 40-channel armature multiplexer modules. Built-in isothermal block with integrated thermocouple reference junction minimizes thermal offset errors during thermocouple temperature measurement - a unique capability among 34980A terminal block offerings. Screw-type connections accommodate wire sizes up to 20 AWG for fewer than 100 connections or 24 AWG for more than 100 connections.

The unit incorporates a hardware safety interlock that shorts Bank 2 pins, preventing inadvertent routing of high voltages from the Analog Bus to the D-sub connector. Relay architecture supports 1:N closure with break-before-make switching.

Technical Specifications

• Voltage rating: ±300 V


• Relay type: 1:N closure (one channel per bank maximum)


• Switching mode: Break-before-make


• Wire gauge: Up to 20 AWG (100 connections)


• Dimensions: 280 H × 178 W × 114 D mm


• Weight: 0.27–0.36 kg

Key Features

• Isothermal block with built-in temperature sensor for thermocouple reference junction


• Hardware safety interlock with automatic Analog Bus relay control


• Detachable screw-terminal design for flexible external wiring


• Channel-by-channel break-before-make relay operation


• Labeled for model identification and slot designation

Compatibility & Integration Designed for integration with Keysight 34921A and L4421A 40-channel armature multiplexer modules within the Keysight 34980A mainframe architecture. Provides discrete wiring interface for thermocouple and general signal measurement applications requiring thermal offset compensation.