4 Features and Functions
210 Keysight 34970A/34972A User’s Guide
34901A 20-Channel Multiplexer
This module is divided into two banks of 10 channels each. Two additional fused
channels are available for making direct, calibrated DC or AC current
measurements with the internal DMM (external shunts are not required). All 22
channels switch both HI and LO inputs, thus providing fully isolated inputs to the
internal DMM or an external instrument. When making 4-wire resistance
measurements, the instrument automatically pairs channel n with channel n+10
to provide the source and sense connections. The module has a built-in
thermocouple reference junction to minimize errors due to thermal gradients
when measuring thermocouples.
TO PREVENT ELECTRICAL SHOCK
To prevent electrical shock, use only wire that is rated for the highest voltage
to any channel. Before removing a module cover, turn off all power to
external devices connected to the module.
CAUTION WITH MULTIPLE SIGNALS
To avoid the possibility of multiple signal sources becoming connected
together, we recommend when multiplexing two or more sources they
should be connected on separate modules or on separate banks of the same
module.
CAUTION WITH HAZARDOUS VOLTAGES
When any channel is connected to a hazardous voltage source, all channels
in the module should be treated as hazardous and all channel wiring in the
module should be rated for the maximum voltage applied. Thermocouples
attached to any other channel on the module should have insulation rated
for the maximum voltage, or have additional insulation added rated for the
maximum voltage and should be isolated from conductive parts using a
thermal compound or tape rated for the maximum voltage applied. Do not
mount, move, or remove any thermocouples when the device under test is
connected to a supply source.
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