The Keysight 34903A module is a universal switching module for the 34970A / 34972A measurement data acquisition / switching system. It has 20 independent single-pole changeover relays (SPDT) and supplies z. B. test objects, control displays and status lights with electricity. It is also used to actuate external power relays, solenoids, ... In combination with the matrix and multiplexer modules, it can be used to build customer-specific switching and test systems. Its changeover contacts (300 V, 1 A) can handle up to 50 W, which are also sufficient for numerous power line switching tasks. A connection to the internal DMM of the 34970A / 34972A is not possible. On the 34903A module there is a perforated grid area for building small circuit expansions.