18 Keysight 34970A/34972A Service GuideThe Plug-In Modules at a GlanceFor complete specifications on each plug-in modules, refer to the modulesections in Chapter 1.34901A 20-Channel Armature Multiplexer– 20 channels of 300 V switching– Two channels for DC or AC current measurements (100 nA to 1A)– Built-in thermocouple reference junction– Switching speed of up to 60 channels per second– Connects to the internal multimeter– For detailed information and a module diagram, see page 151.Each of the 20 channels switches both HI and LO inputs, thus providing fullyisolated inputs to the internal multimeter. The module is divided into two banks of10 two-wire channels each. When making four-wire resistance measurements,channels from Bank A are automatically paired with channels from Bank B. Twoadditional fused channels are included on the module (22 channels total) formaking calibrated DC or AC current measurements with the internal multimeter(external shunt resistors are not required). You can close multiple channels on thismodule only if you have not configured any channels to be part of the scan list.Otherwise, all channels on the module are break-before-make.34902A 16-Channel Reed Multiplexer– 16 channels of 300 V switching– Built-in thermocouple reference junction– Switching speed of up to 250 channels per second– Connects to the internal multimeter– For detailed information and a module diagram, see page 153.Use this module for high-speed scanning and high-throughput automated testapplications. Each of the 16 channels switches both HI and LO inputs, thusproviding fully isolated inputs to the internal multimeter. The module is dividedinto two banks of eight two-wire channels each. When making four-wireresistance measurements, channels from Bank A are automatically paired withchannels from Bank B. You can close multiple channels on this module only if you
