Agilent 34980A Multifunction Switch/Measure Unit *34980-90005*
Agilent 34980A Multifunction Switch/Measure Unit *34980-90005*
Agilent 34980A Multifunction Switch/Measure Unit *34980-90005*
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<strong>Measure</strong>ment Input<br />
Introduction to the <strong>34980A</strong> 1<br />
The <strong>34980A</strong> allows you to combine a DMM (either internal or external)<br />
with multiplexer channels to create a scan. During a scan, the instrument<br />
connects the internal DMM to the configured multiplexer channels one at<br />
a time and makes a measurement on each channel.<br />
Any channel that can be "read" by the instrument can also be included in<br />
a scan. This includes any combination of temperature, voltage, resistance,<br />
current, frequency, or period measurements on multiplexer channels. A<br />
scan can also include a read of a digital port or a read of the totalizer<br />
count on the digital modules.<br />
The Internal DMM<br />
A transducer or sensor converts a physical quantity being measured into<br />
an electrical signal which can be measured by the internal DMM. To<br />
make these measurements, the internal DMM incorporates the following<br />
functions:<br />
Temperature (thermocouple, RTD, and thermistor)<br />
Voltage (dc and ac up to 300V)<br />
Resistance (2- wire and 4- wire up to 100 M)<br />
Current (dc and ac up to 1A)<br />
Frequency and Period (up to 300 kHz)<br />
The internal DMM provides a universal input front- end for measuring a<br />
variety of transducer types without the need for additional external<br />
signal conditioning. The internal DMM includes signal conditioning,<br />
amplification (or attenuation) and a high resolution (up to 22 bits)<br />
analog- to- digital converter. A simplified block diagram of the internal<br />
DMM is shown below.<br />
Analog<br />
Input<br />
Signal<br />
Signal<br />
Conditioning<br />
Signal Conditioning, Ranging, and Amplification<br />
Analog input signals are multiplexed into the internal DMM's<br />
signal- conditioning section—typically comprising switching, ranging, and<br />
amplification circuitry.<br />
If the input signal is a dc voltage, the signal conditioner is composed<br />
of an attenuator for the higher input voltages and a dc amplifier for<br />
the lower input voltages.<br />
<strong>Agilent</strong> <strong>34980A</strong> Mainframe User’s Guide 11<br />
Amp<br />
Analog to<br />
Digital<br />
Converter<br />
Main<br />
Processor