The Keysight 34970A Data Acquisition / Data Logger Switch Unit consists of a three-slot mainframe with a built-in 6 1/2 digit digital multimeter. Each channel can be configured independently to measure one of 11 different functions without the added cost or hassles of signal-conditioning accessories. Choose from eight optional plug-in modules to create a compact data logger, full-featured data acquisition system or low-cost switching unit. On-module screw-terminal connections eliminate the need for terminal blocks and a unique relay maintenance feature counts every closure on every switch for easy, predictable relay maintenance. Our most popular module 34901A features a built-in thermocouple reference and 20 two-wire channels.