Agilent Technologies 34450A Installation and operating instructions

Tips and Tricks for
Using the 34450A 5½ Digit
Bench Top Digital Multimeter
Application Note
The Agilent 34450A 5½ digit multi-purpose digital multimeter
(DMM) offers a variety of advanced features and capabilities.
This application note provides five key insights and tips on the
functionality, performance, and the use of this DMM, which are
aimed at helping you work faster and more efficiently.

2
Figure 1. Dual display measurements on 34450A.
Table 1. Measurements available in dual display mode.
When using a DMM with a single
ADC, there are a few ways to
minimize dead time between dual
measurements and increase the
refresh rate of both readings. One
means is to manually set the correct
range for primary and secondary
measurements. Leaving the 34450A
in auto-range mode can prolong dead
time because the DMM will search
for the correct range before making
each measurement.
Another way to optimize
measurement speed while in dual
display measurement mode is to
set both the primary and secondary
measurement to the same resolution.
Unless different resolution is required
between the two measurements,
having one measurement in slow
mode and another measurement
in fast mode decreases the overall
throughput.
Primary Display
Secondary Display
DCV ACV DCI ACI Frequency
DCV
√√√
ACV
√√√√
DCI
√√
ACI
√√ √
Frequency
√√
Tip 1: Dual Display
Measurement
In electronic industries, voltage
and current measurements are
fundamental measurements made
regardless of whether the signal
source is AC or DC. Typically, there is
a desire to monitor both voltage and
current values on a circuit without
repeatedly breaking connection in
the circuit, and switching the DMM
probes between making voltage and
current measurements. You may also
need to measure the AC component
or noise level that sits on top of a DC
signal. In another instance, it may
be necessary for you to measure
the frequency of an AC signal while
reading its voltage or current.
All the measurement examples above
are performed with ease using the
dual display measurement function of
the 34450A. The function allows the
DMM to make two measurements
and display both results on the
34450A’s OLED display that provides
visibility over a large viewing angle
(See Figure 1). Table 1 shows the
measurement combinations available
when the 34450A is operating in dual-
display measurement mode.
The 34450A has a high speed analog-
to-digital converter (ADC) that takes
samples from the input terminals.
When using the 34450A‘s dual display
measurement feature, the internal
circuitry switches between making
primary and secondary measurements
so that the ADC takes samples for
both measurements. This eliminates
the need for a dual ADC, and thus
reduces the price of the DMM.

Tip 2: Triggering
The 34450A has a triggering function
that allows you to initiate a measure-
ment at desired conditions. The
triggering feature is used through the
front panel during manual operation,
while for automated operation the
DMM is controlled through the USB,
GPIB, or serial connector. Setting the
34450A to be triggered must be done
in the proper sequence to ensure
the DMM starts measuring once
the triggering signal is received. The
DMM’s measurement function, range,
resolution, and speed are among the
first few settings that need to be
set. Leaving the DMM in auto-range
reduces the overall speed of each
measurement because an additional
algorithm is used to search, compare,
and set the right measurement range.
Manually setting the measurement
range is always a good practice when
the measurement values are known.
When the DMM is to be used in auto-
mated or remote mode, it can be set
to receive a triggering signal either
through the software or hardware.
Software triggering (also known as
bus triggering) is achieved by sending
standard commands for programma-
ble instruments (SCPI) commands to
the DMM over a USB, GPIB, or serial
connection. This triggering method
is preferred in software-controlled
environments where the test program
determines the measurement timing
by sending a *TRG command to the
DMM. If your application requires
data analysis or the comparison of
values before making a decision
to continue a measurement on the
DMM, using a software trigger is the
best approach.
Using hardware triggering is recom-
mended when using the DMM to
make one or a specified number of
measurements upon receiving a pulse
at the TRIG IN pin on the serial con-
nector. Hardware triggering through
the serial connector is best suited for
manufacturing environments where
instruments or mechanical parts, such
as handler and PLC, provide a pulse to
the DMM to trigger a measurement.
Using the TRIG IN pin of the 34450A
is a good choice if a triggering pulse
is available in the test environment
and throughput is one of the major
concerns. Figure 2 refers to the
serial connector at the rear panel of
the 34450A. The triggering signal is
applied to the TRIG IN and Ground
pin of the serial connector as denoted
by a positive and negative sign
respectively.
Figure 3. Types of triggering methods on 34450A.
In manual operation or local mode,
the triggering is meant to initiate a
single measurement or start the data
logging using the timing you define.
This triggering method is initiated by
pressing [Trig]. To manually trigger a
single measurement, set the DMM’s
triggering source to Manual/External
in the Utility menu. The triggering
method for data logging is explained
in the Tip 3 section of this application
note. Figure 3 outlines the triggering
operations on 34450A with criteria for
your selection reference.
Triggering Operation
Manual
Software
Automated
Hardware
• Measure upon receive
*TRG command.
• Best for software-
controlled environment.
• Use with data logging
or initiate a single
measurement.
• Control via front
panel.
• Required pulses to
be triggered.
• Utilize TRIG IN pin
at the serial port.
• Higher throughput.
Tx Rx Trig In Trig Out
Figure 2. TRIG IN pin on the serial connector of the 34450A.
3

4
Tip 3: Data Logging
Another 34450A feature allows you
to store measurement results into its
50k non-volatile memory through the
data logging function. You can per-
form data logging when using either
single or dual display measurements.
. The data stored in memory is acces-
sible from your computer through the
USB, GPIB or serial connector on the
rear panel of the 34450A.
Data logging on 34450A is initiated in
two ways: manually pressing [TRIG]
on the front panel, or by supplying a
triggering pulse to the TRIG IN pin at
the rear panel of the DMM. Manually
pressing [TRIG] allows you to have
full control over when to start acquir-
ing readings, while using a triggering
pulse immediately starts data acquisi-
tion. For timing sensitive applications
and repetitive test routines, using a
triggering pulse improves the overall
throughput.
Data logging speed is subject to a
couple of factors. The resolution of
the measurement determines the
minimum sample interval during
data logging. To illustrate, logging
100 DCV readings in fast mode for a
user-defined range is completed in
approximately 7 seconds. However,
the same DCV readings take approxi-
mately 82 seconds to complete if
the 34450A is running in slow mode,
and approximately 268 seconds if the
34450A is running in auto-ranging
slow mode. Table 2 lists the minimum
sample interval over the common
measurement functions at three
different resolutions in manual and
auto ranging.
Table 2. Minimum sample interval (in second) for data logging.
Resolution
DCV DCI ACV ACI 2-wire Ohm 4-wire Ohm
manual
range
auto
range
manual
range
auto
range
manual
range
auto
range
manual
range
auto
range
manual
range
auto
range
manual
range
auto
range
Fast Mode 0.0690 0.7475 0,0690 0.6670 0.0690 1.4950 0,0575 1.3800 0.0810 0.9200 0.3335 2.9325
Medium Mode 0.0805 1.1155 0.0977 0.9200 0.1610 2.2310 0.1150 1.7940 0.1840 1.5065 0.4715 3.4730
Slow Mode 0.8165 2.6795 0.9430 2.0700 0.8165 10.4530 0.7015 6.9920 1.0465 3.6110 1.5065 4.3700

Figure 4. Selecting or recalling the store location can be done easily on the front panel of the 34450A.
Tip 4: Storing and
Recalling Settings
On top of the 50k non-volatile memory
for data logging function, the 34450A
has six non-volatile memory locations
for storing the DMM’s settings such
as measurement configuration, math
operation, and system operations.
The 34450A stores the last DMM
configuration at location LAST before
it shuts down, while Locations 1
thru 5 are available for storing your
preferred configurations.
The store and recall function is
particularly useful for operations
where multiple test profiles must be
performed by a single 34450A. You
can store the DMM’s configuration at
any time and recall it as needed. The
store and recall function is accessible
during both manual and remote
operation. Using this function helps
eliminate the need to repetitively
program the DMM with the same
configuration, allowing you to quickly
perform your measurements without
having to do extensive programming
or manually set the DMM for the
same measurement previously
performed.
For example, if your measurement
requires multiple test points and
each has different needs in terms of
measurement functions, range, and
resolution, you can dedicate a specific
memory location to the test points.
Whenever you need to measure the
test point, you simply recall that
specific memory location. The store
and recall feature is supported in both
local and remote modes.
5

6
Tip 5: Limit Test
Limit test is an extra value-added
feature of the 34450A. When the
limit operation is enabled, the
DMM instantly notifies you if a
measurement result falls outside the
high or low limits you establish prior
to making a series of measurements.
Upon setting the 34450A to limit
operation, the DMM’s display is
divided into four segments as shown
in Figure 5. The two segments on
the left are for setting the high and
low limits. The upper right segment
displays the last measurement and
the lower right segment displays the
limit results; whether it is pass, fail
low, or fail high.
Figure 5. The display of 34450A in limit operation.
Limit operation is extremely useful
for manual operations. There are
many simple and low cost production
tests require only one DMM to
perform a specific test. For example,
measuring the voltage across an LED
to determine whether it is within
its tolerance can be done easily
using the limit test function of the
34450A. The 34450A displays “PASS”,
“FAIL-LO” or “FAIL-HI” based on the
limits set. Apart from displaying the
measurement value with a pass or fail
identification, the 34450A beeps to
alert the operator when a measured
value falls outside the set limits. You
can put the 34450A into the limit
operation by pressing [Shift] > [Math].
Conclusion
The 34450A 5½ digit multimeter
offers superior ease of use on the
bench and for remote operations.
Whether your application requires
general purpose measurements, or
fast throughput and programming
speed, using the tips provided will
help you optimize the capabilities
of your 34450A DMM.
Related Literature
Please refer to the publication below for further information.
Publication title Publication number
Agilent 34450A 5½ Digit Dual Display,
Benchtop DMM, Data Sheet
5991-1133EN
Agilent 34450A 5½ Digit Multimeter User’s Guide 34450A-90000

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Revised: October 11, 2012
Product specifications and descriptions
in this document subject to change
without notice.
© Agilent Technologies, Inc. 2013
Published in USA, January 18, 2013
5991-1518EN
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