Introduction to the 34980A
1
Keysight 34980A Mainframe User’s Guide
25
Measurement Input
The 34980A allows you to combine a DMM (either internal or external) with
multiplexer channels to create a scan. During a scan, the instrument connects the
internal DMM to the configured multiplexer channels one at a time and makes a
measurement on each channel.
Any channel that can be "read" by the instrument can also be included in a scan.
This includes any combination of temperature, voltage, resistance, current,
frequency, or period measurements on multiplexer channels. A scan can also
include a read of a digital port or a read of the totalizer count on the digital
modules.
The Internal DMM
A transducer or sensor converts a physical quantity being measured into an
electrical signal which can be measured by the internal DMM. To make these
measurements, the internal DMM incorporates the following functions:
– Temperature (thermocouple, RTD, and thermistor)
– Voltage (dc and ac up to 300V)
– Resistance (2-wire and 4-wire up to 100 M
Ω
)
– Current (dc and ac up to 1A)
– Frequency and Period (up to 300 kHz)
The internal DMM provides a universal input front-end for measuring a variety of
transducer types without the need for additional external signal conditioning. The
internal DMM includes signal conditioning, amplification (or attenuation) and a
high resolution (up to 22 bits) analog-to-digital converter. A simplified block
diagram of the internal DMM is shown below.
Analog
Input
Signal
Signal
Conditioning
Amp
Analog to
Digital
Converter
Main
Processor
