Agilent 34970A/34972A Data Acquisition / Switch Unit

Chapter 5 Theory of Operation
Switch Modules
The 16 channels are divided into two banks. The banks are combined by
closing K327 for voltage and 2-wire Ohms switching. When K327 is open,
the banks are electrically independent of each other and this
configuration is used for 4-wire Ohms multiplexing where the Ohms
current source is connected to channels 1 through 8 and the sense is
obtained from channels 9 through 16. Relays K326 and K328 control the
connection to the analog bus for measurements using the internal DMM.
Module Reference
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