Measurements you can
trust
We took the measurement engine
from our best-selling benchtop
DMM and embedded it inside a
3-slot cardcage. You get the benefit
of proven HP measurement
performance, universal inputs with
built-in signal conditioning, and
modular flexibility, all in a low-cost,
compact data acquisition package.
The HP 34970A features 61/2 digits
(22 bits) of resolution, 0.004% basic
dcV accuracy, and ultra-low reading
noise. Combine that with scan rates
of up to 250 channels/sec, and
you’ve got the speed and accuracy
you need to get the job done right
the first time.
Powerful flexibility to
get your job done
Whether you need to measure
temperature, ac/dc volts, resistance,
frequency or current -- the
HP 34970A can handle it. The
internal autoranging DMM directly
measures 11 different functions,
eliminating the need for expensive
external signal conditioning. And
our unique design allows complete
per-channel configurability for
maximum flexibility and quick, easy
set up. It’s like having an
independent,
high-performance DMM behind
each channel.
Custom configurations
that grow with you
Three module slots and eight
switch/control modules allow you
to customize the HP 34970A to meet
your unique requirements. Buy only
what you need -- and add more
modules later as your application
grows.
Unequaled
ease of use
From the simplified configuration
procedures, to the self-guiding front
panel interface, we put in extra time
and energy to save yours. Simple
things --like on-module screwterminal connectors, built-in
thermocouple reference junctions,
well-organized user documentation
full of examples and hints, and a
standard “getting started” kit that
will have you making
measurements 15 minutes out of
the box -- all add up to increased
productivity, whether you use the
instrument every day or only now
and then.
Free software to save
you time and money
Now you don’t have to spend your
valuable time writing or configuring
software. HP BenchLink Data
Logger software gives you a familiar
Microsoft Windows®interface for
test configuration and real-time
data display and analysis. Even
better, this full-featured data
logging application is included free
with every standard HP 34970A.
What can you expect
from a data acquisition system
that’s this affordable?
Just about
everything!
HP 34970A Data Acquisition/Switch Unit
More power and flexibility
than you ever imagined
you could afford
3-slot mainframe
offers up to 96 matrix crosspoints or
120 single-ended channels
3-year warranty to protect your investment
HP BenchLink Data Logger
software included;
drivers available for HP VEE and
National Instruments LabVIEW
®
Intuitive front panel: task-oriented,
self-guiding menus
50k readings of non-volatile
memory holds data when
power is removed
HI/LO alarm limits on each input
channel, plus 4 TTL alarm outputs
Scaling function for
converting raw inputs
into user-defined units
6
1
/2-digit (22-bit) internal
DMM measures 11 functions without
external signal conditioning
8 switch and control
plug-in modules to
choose from
Battery-backed real-time clockfor pacing
scans and timestamping readings
Built-in HP-IB and RS-232 interfaces
Monitor display
mode lets you
keep an eye on
tests in progress
Following are technical specifications for the HP 34970A Data
Acquisition/Switch Unit and its
modules. The explanations and
examples below are helpful in
understanding how to interpret
these specifications:
• Measurement accuracy is
specified as percent of reading
plus percent of range, where
reading is the actual measured
value and range is the name of
the scale (1V, 10V, etc)—not the
full scale value (1.2V, 12V,etc.).
• DMM measurement accuracies
include all switching errors.
Switching errors are also listed
separately in the module
specifications section.
Temperature measurement
accuracies include ITS-90
conversion errors. The
thermocouple accuracies include
the reference junction error as
well.
• Accuracies are listed as either
24-hour, 90-day or 1-year
specifications. This refers to the
length of time since the
instrument’s last calibration.
Use the specification that
matches your calibration cycle.
The 24-hour specifications are
useful for determining short-term
relative performance.
EXAMPLE 1: Basic dcV accuracy
Calculate the accuracy of the
following measurement:
9 V dc input
10 V dc range
1 year accuracy specifications
Normal operating temperature
(18ºC - 28ºC)
From the following page, the 1-year
accuracy is
0.0035% of reading + 0.0005%
of range
Which translates into
(0.0035/100 x 9 V)+
(0.0005/100 x 10 V) = 365µV
For a total accuracy of
365 µV / 9 V = 0.0041%
EXAMPLE 2: Extreme
operating temperature
When the HP 34970A is used
outside of its 18ºC-28ºC
temperature range, there are
additional temperature drift errors
to consider. Assume the same
conditions in example 1, but at a
35ºC operating temperature:
The basic accuracy is again
0.0035% of reading + 0.0005% of
range=365 µV.
Now, multiply the 10 V temperature
coefficient from the following page
by the number of degrees outside of
operating range for additional error:
(0.0005% reading + 0.0001%
range)/ºC x (35ºC - 28ºC) =
(0.0005% reading + 0.0001%
range)/ºC x 7ºC =
0.0035% reading + 0.0007% range
= 385 µV
Total error is then
365 µV + 385 µV = 750 µV or
0.008%
EXAMPLE 3: Thermocouple
measurement accuracy
Calculating the total thermocouple
reading error is easy with the
HP 34970A—just add the listed
measurement accuracy to the
accuracy of your transducer.
Switching, conversion, and
reference junction errors are
already included in the
measurement specification.
For this example, assume a J-type
thermocouple input reading 150ºC.
From the following page,
total error is
Thermocouple probe accuracy +
1.0 ºC
The probe vendor specifies
accuracy of 1.1ºC or 0.4 %,
whichever is greater
Total error is then
1.0ºC + 1.1 ºC = 2.1ºC total,
or 1.4 %
EXAMPLE 4: acV Accuracy
The acV function measures the true
RMS value of the input waveform,
regardless of waveshape. Listed
accuracies assume a sinewave
input. To adjust accuracies for nonsinusoids, use the listed crest factor
adder.
For this example, assume a ±1 V
square wave input with 50% duty
cycle and a 1 kHz frequency.
Accuracy for 1 V, 1 kHz sinusoid is
0.06% reading + 0.04% range
A 50% duty cycle squarewave has
a crest factor of
Peak Value / RMS value = 1 V / 1 V
= 1
From Crest Factor table, add
0.05% of reading
The total accuracy is
0.11% of reading + 0.04% of
range = 1.5 mV or 0.15 %
HP 34970A Technical Specifications
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