RoadTest: RoadTest the Keysight U1282A Digital Multimeter
Author: shabaz
Creation date:
Evaluation Type: Independent Products
Did you receive all parts the manufacturer stated would be included in the package?: True
What other parts do you consider comparable to this product?: Fluke 289, Fluke 87V
What were the biggest problems encountered?: Due to feature-richness often the user manual needs to be consulted to recall how to use some of the less common features
Detailed Review:
I received the U1282AU1282A to RoadTest a very long time ago, and I got to write a bunch of blog posts on it. They can be read here:
U1282A Test Bed Integration and Testing the Raspberry Pi 3
U1282A Vehicle/Automotive and Industrial Applications
Through these blog posts there was lots of experimentation with writing custom software for data logging and integrating with MATLAB, checking the power output from lasers, working with Bluetooth for remote measurement and logging in vehicles, and working with sensors such as thermistors, magnetic flux density sensors, and optical based frequency measurement with a phototransistor. There were specific features of the U1282A that lent themselves well to these experiments.
But, I must admit, my first impressions were that perhaps the multimeter is too large and bulky, less familiar than a Fluke, and kind-of complicated to use! It’s not the Apple Mac of the multi-meter world. But, I’ve had the device for a year now, and a valid question is, would it replace or find more uses than my current multimeter and do I find myself using it more regularly now?
The long story cut short is that yes, the multimeter has grown on me and I do find myself using it more. The killer features of this multimeter are the high-speed logging capability and the extremely high resolution. I find myself using it more frequently than a bench multimeter.
The initial impression that the multimeter was complicated to use was not so wrong however. It isn’t intuitive until you’ve spent some time familiarizing with it. The good thing though is that it is possible to speed up using it. To help in that respect, this blog post will try to walk some of the hopefully most interesting features.
In terms of the size of the multimeter, unbelievably I’ve come to like it. It does take up a lot of room (let’s be honest, it is the same depth and height as an oscilloscope when it is on its stand!) but that is the price one pays to have a product that contains sensitive circuitry. When it comes to extremely high resolution even a slight flexing of a PCB can be sufficient to cause errors. The shell of highly accurate multimeters needs to be extremely rigid to counter this. It is the Volvo of multi-meters. Furthermore the U1282A is ruggedized and water resistant. For me the latter features are nice-to-haves rather than essentials but it does mean I’m confident using it outdoors.
I had a lot of fun exploring its features in the earlier blog posts and now, almost a year on, and a lot of familiarity with the U1282A multimeter, it is nice to revisit it and share my findings; I hope they are useful.
This review is arranged as a tour of the types of measurements you might want to perform with the multimeter. I’ve arranged it in the order of the dial on the multimeter! But interspersed with other stuff in places. Also I’ve tried to have some diagrams as a quick reference and they can be used in two ways:
This was a flagship feature of the U1282A. It is capable of very high-speed (for a multimeter) logging at 10Hz. The meter comes with an isolated USB cable and communication with the meter is done in the standard manner for test instruments, using SCPI formatted messages at 9600 baud.
The supplied software worked fine on the PC but I developed my own fastlog code to allow integration with arbitrary third party software. There is also a fastlog.m file there for directly importing real-time measurements into MATLAB for live analysis and plotting.
The data logging was so fast and useful, I had to try out the Bluetooth wireless capability. This is a separately-purchased 100 meter range Bluetooth moduleBluetooth module that plugs onto the back of the multimeter and provides measurements directly to your mobile phone using ‘Keysight Meter Logger’ software. This is incredibly useful when working in a vehicle. I was able to connect the meter to the car battery and then sit inside the vehicle and use my phone to monitor the battery voltage when starting the car. There are even voice alerts to avoid taking your eyes off the task at hand.
A simple but extremely powerful capability of the software is the ability to apply conversions. It is possible to create any formula and the meter will apply it in real-time to the measurements. So, as an example, the software can directly display revolutions per minute (RPM) if connected to an appropriate sensor. I used it with a thermistor to directly display the actual temperature rather than a resistance value, to measure length in mm rather than display a resistance value of a linear potentiometer and to display magnetic flux density directly in Gauss.
At the first position on the settings dial, the U1282A provides the usual AC voltage measurements. But, since there is a dual display, some additional information is on the screen too. Normally this is the ambient temperature – very useful, but by holding down the ‘Dual’ button (which doubles as an illumination switch if you press briefly) the dual displays cycle through some additional modes. After the first long-press, the temperature gets replaced with the frequency of the AC waveform. Another long-press pushes the main display up to the smaller display, and the large display shows the voltage measurement in dBm. This is relevant if you’re measuring the voltage across a 50 ohm load. Press again, and the display is in dbV (dB relative to 1V).
If you’re curious about the AC waveform and want to know the value of the peaks over time, then there are a couple of things you can do.
Firstly, if you hold down the ‘Peak’ button for a few seconds, then the multimeter displays the max peak level captured over time. You can then toggle between max and mix by briefly pressing that button. Note that this will only really be accurate for low frequencies (e.g. mains frequency). There will be an error if you think it will measure the peaks for (say) a 1kHz signal. To reset the peak over time measurement, the Hold button needs to be pressed which is non-intuitive.
Also note that the Peak mode only looks at the AC component. If there is a DC offset, you won’t know from the Peak mode min/max values; see the DC Measurements section below to see how to do that.
If you’re curious about the change in RMS value then press briefly min/max without having first held it down for a long time (the long press puts it into the peak level mode).
If you have high-frequency components on the AC waveform you can filter them out by hitting the orange Shift button on the U1282A to enable the low-pass filter.
The second setting on the dial is for mV AC, and it behaves much the same as the previous setting, except that you can get down to a thousandth of a mV (i.e. uV) resolution. This is extremely good resolution; at least a digit more than the popular Fluke 87V, and two digits if you’re not in the latter’s ‘high-resolution’ mode.
The U1282A is specified for AC RMS measurements between 20 Hz and 100 kHz, however the response is still fairly accurate down to 10 Hz. I found the AC RMS feature highly useful, especially because it supports such a wide frequency range (this is rare with multimeters!) and because of the very granular measurements down to microvolts. This is excellent for performing frequency response measurements for amplifier circuits (way more accurate than an oscilloscope of course), as well as performing RMS noise measurements. This excellent, wide bandwidth AC RMS capability is an extremely compelling reason to choose the U1282A multimeter. I have found the measurements to be extremely accurate with a range of signal inputs and in agreement with automated measurements from an oscilloscope.
The U1282A has a good set of frequency measurement capabilities. They are available in several modes of operation, but the two most useful modes are when the dial is in the AC position, and when the dial is in the dedicated Frequency Counter position.
The AC mode allows signal inputs up to the limits of the multimeter’s AC range (i.e. 1kV) but with a typical usable maximum frequency measurement capability of the order of several hundred kHz (it varies depending on the range and the input signal level).
Note that further along the dial the dedicated Frequency Counter mode provides far higher frequency measurement capability but is restricted to lower voltages. It is explored in a section further below.
The AC mode is useful even if there is a DC offset to the input signal. The capabilities are enabled by pressing the Hz button while the dial is set in the AC mode. The diagram here shows the types of things that can be measured by button manipulations on the U1282A.
The capability to measure pulse width is very handy, I’ve used it for testing servo driver code. It shows the pulse width and pressing MaxMin reveals any pulse width jitter.
So, the majority of the useful features in AC modes have been covered. On to the next range, and we’re into the DC measurement zone. This is a very interesting place to be because of some strong capabilities for combined AC+DC signal measurements.
Like any typical multimeter the U1282A has the usual DC Voltage measurement mode. However there is the capability to characterize a signal in more detail if you think there is an AC component present too. See the diagram and table here to explore what measurements are possible and the dial and button settings that are needed.
The combined AC+DC RMS mode is very cool; it accurately shows the equivalent DC voltage value that would be needed to dissipate an amount of power in a resistor that the input AC+DC component signal would achieve. This is a function that many earlier multimeters can not perform but modern ones do.
A capability that is very useful in many measurement modes but will particularly be useful for DC and resistance measuring modes is the Null feature, also known as Relative mode. As the name suggests it allows for an offset to be temporarily zeroed out, so that the displayed value shows the delta. As an example in resistance mode, the offset could be the wire resistance. To enable, the Null button can be pressed in most modes and a delta symbol is displayed to show that the display is now zeroed. Null mode is not always seen on many multimeters, but it is incredibly useful.
The amount of offset that was subtracted can be revealed at any time by pressing Null again; it is displayed for a few seconds.
To exit the null mode is a little awkward. The Null button needs to be pressed to display the amount of offset, and then the Null button needs to be pressed again quickly during those few seconds. This mode exit system is the type of thing that is easy to forget, and I often found myself just rotating the dial (which has the effect of exiting the Null function) and then rotate the dial back.
Sometimes highly accurate resistance measurements are necessary. One example is when measuring the temperature of an object using a thermistor. The U1282A has very good, and very accurate resistance measurement capability. The only slight negative for resistance measurements is the slow time to autorange (usually this is not an issue for general resistance measurements).
One particular benefit is the 60 ohms range (with 1 milliohm resolution); this allows measurements to within +-100milliohms across most of the range.
The fast logging capability means the U1282A is excellent for measuring the temperature of components during tests with a small thermistor. The free Android app can apply a formula on the fly for real-time conversions. See the Automotive Applications blog for the formula to use with a low-cost thermistor from Farnell.
Incidentally, the meter came with a very fancy Remote Switch ProbeRemote Switch Probe (not available in all bundles; it can be a separate purchase) which can speed up measurements across multiple components or circuit boards. The probe handle has a button on the side which is pressed to automatically log a measurement into the meter memory or to the attached PC. It could be used to check a batch of resistors or to document a reference voltage level on many boards or to capture a measurement without taking your eyes or hands off a task.
The Continuity Check capability has some very nice touches. There is also a red LED on the U1282A, and it lights up briefly whenever the continuity tone sounds, so this is ideal for a loud environment. The tone and LED response is fast. There is also the possibility to tweak the resistance threshold for the continuity check, by setting a manual range for resistance. This could be handy where inductor or motor windings need a continuity check.
The Diode Check capability functions as expected, beeping briefly to indicate a valid forward biased diode voltage drop. The display will indicate the forward voltage drop for diodes and most LEDs.
Continuity and diode checking are standard capabilities on most multimeters but the frequency counter mode is novel. This is distinct from the frequency measurement capabilities (up to a few hundred kHz depending on signal level) that were present in the modes discussed earlier such as AC mode. The dedicated frequency counter is a separate function intended for very high frequency measurements up to 100MHz! I tested it with a 20MHz signal at less than 100mVp and it correctly measured the frequency. The dedicated frequency counter mode has limitations however; the input must not exceed +-1.8Vp. Although this restricts its usefulness as a general-purpose frequency counter, it could still be useful to build into test beds, driven by custom hardware or a low voltage logic output.
The U1282A has capacitance measuring capability and there are 8 ranges with a minimum resolution of 1pF. It is adequate for basic component testing. For measurements that are more detailed a dedicated LCR or capacitance meter is always preferred so that there is more control over the test frequency. The U1282A measures at a low frequency (it depends on the capacitance but is less than 1kHz).
The U1282A has a good set of ranges for current measurement. I liked that for low current measurements it performs as well as most other high-end handheld multimeters if not better. The lowest current range has a resolution of 10nA which is great. And it is accurate too; see the Accuracy Charts section further below. Since the meter has 60,000 counts display resolution, this means that 10nA granularity is available all the way up to 600uA. Also, at the lowest current measurements for (say) devices in sleep mode that may be consuming less than a microamp of current, the worst-case error is tiny; about 0.1uA. This is great for confirming devices actually have gone into deep sleep modes and are not in shallow sleep modes, and for checking leakage.
A negative point was the very slow auto-ranging in current measurement mode; it took close to five seconds to autorange. Measurements were quick when the range was set manually.
In terms of current waveform measuring capabilities, the U1282A supports similar scenarios as for voltage measurement. The table above shows the capabilities and how to access them with the dial and buttons.
The meter has industrial use-cases and can auto-convert a 4-20mA measurement into a percentage value (industrial sensors use this method known as ‘current loop’ to transfer information in order to eliminate wire resistance voltage drop from causing a measurement error, and sometimes to supply current to the sensor using the same wires).
The AC current measurement capabilities are as rich as for AC voltage measurement. At its most granular, the resolution is 10nA which is about as good as it gets with a handheld multimeter.
Interestingly the U1282A also has an output signal capability. It is quite restricted and although I have not got an immediate use for it, it is good to know it is there. It could be used to slowly pulse logic circuits, basic circuit calibration, or for generating PWM. Only certain select frequencies are supported from 0.5Hz to 4.8 kHz.
There is little point duplicating specifications that can be obtained from datasheets. However, I was curious to find out what the measurement error impact was for the U1282A compared with a couple of competitor products (I chose to compare with the Fluke 87V which is slightly lower cost than the U1282A, and the Fluke 289 which is slightly higher cost than the U1282A, but prices vary immensely though).
To cut a long story short, the summarized finding is that the U1282A and Fluke 289 are very close to each other. The Fluke 87V is a more dated design and across most of the span for each range it doesn’t perform as well. Across most of the span for the measurement ranges that were compared, sometimes the Fluke 289 wins out and sometimes the U1282A wins out, depending on the particular range being used and the input signal level. But in general the two are extremely close. At the very low end of ranges often the Fluke 87V wins, however usually it is for an extremely narrow portion of the span, and furthermore the Fluke 87V needs to be set into its slower ‘hi-res’ mode to achieve this.
The accuracy in datasheets is specified as a percentage plus a number of ‘counts’. It is not intuitive to get a comparative feel of how accurate the multimeter is compared to other multimeters because of this multi-dimensional way of specifying accuracy.
For those that want detail, I plotted the charts here for some of the measurement ranges (not all! there are too many) so that a reasonable comparison can be made. The charts take into account the multi-dimensions. I’ve focussed on low DC voltage, current and resistance measurements here. If there is interest then I’m happy to repeat the exercise for any desired measurement range; just let me know in the comments below.
I hope the charts are easy to use and can serve as a reference whenever a ballpark idea of measurement accuracy is needed for any of the three multimeters here. Basically, look for the type of measurement you want to perform and then on the x-axis seek out the value that you wish to measure, e.g. 20mV. Then, on the y-axis you can see the worst-case measurement error for each of the three multimeters. Any value within the shaded area is considered in-spec.
So, if you wanted to measure 20mV then you'd go to the "Millivolt Measurement Error" chart, and look up 20mV on the x-axis. The chart shows that the U1282A would have an error of no more than about +-20uV. The Fluke 87 V and 289 would have errors of no more than about +-28uV.
As another example, to see the potential error for a measurement of 4mA, go to the "Milliamp Measurement Error" chart and it can be seen that the U1282A and Fluke 289 would have approximately the same worst-case error of about +-2.5uA, but the Fluke 87 V would have a worst-case error of about +-8uA. These are all extremely low values of course for a handheld multimeter. All three of these models and in particular the Fluke 289 and U1282A have incredible performance.
It is hard not to be impressed by this multimeter. It is has lots of exciting features not ordinarily seen. For me by far the most useful capability is the high-speed logging. I also liked the remote Bluetooth wireless functionality and the ability to apply maths conversions on-the-fly to measurements as they arrive.
This is the first handheld multimeter I’ve used with SCPI capability and it was straightforward to write code in different languages to communicate to it and collect the high-speed logging data.
The core functions of the multimeter are executed very well; there is excellent granularity due to the multiple ranges and 60,000 count display and measurements were extremely quick (10 Hz logged and 5 Hz displayed) although some modes did slow down more than other modes when autoranging.
There is a multitude of views possible with the dual display and generally, the capabilities are consistent; what is available for the voltage measurement modes is also available for the current measurement modes. There is some difficulty in remembering some mode settings unless you use that setting often. A display with more text and a few more buttons could have improved the user interface I think, but a higher-res display could have cost increased current consumption. The U1282A has a very impressive 800 hours battery life during operation. I have not replaced the cells for a year.
The meter is highly configurable and has a menu system that is accessed by powering up the multimeter while the Shift key is pressed.
The meter competes directly with other high-end handheld multimeters and the performance for the core functionality is as good if not better than other devices across many of the popular ranges that were examined, across most of the span. The display update is a speedy 5Hz.
The Bluetooth adapter is highly recommended. It is invaluable for field measurements or just working in the car.
The meter crosses into the boundaries of several existing test tools. The basic measurements are augmented with some modern capabilities like measuring DC and AC RMS components. The high speed logging and temperature measuring capability (either using a thermocouple or just a thermistor) could save hundreds of dollars because the U1282A functions just as well if not better, and faster, compared to a dedicated temperature logger. The standards-based interface allows users to create their own custom logging and plotting apps or use off-the-shelf free software from Keysight for the PC or mobile phone.
Digital signals such as PWM, can be measured and generated with the U1282A. The measurement capability in particular is very good with a very large frequency counter range (100MHz) and positive- and negative-going pulse width measurements and percentage conversions.
While the meter cannot replace a chart recorder, data logger, oscilloscope and frequency counter, it performs pretty well in these roles for many scenarios! Thank you U1282A for turning us engineers into the MacGuyvers (in our heads at least!) of the measurement world.
Top Comments
Shabaz,
it is an annoying fact that you write great posts; you'll surprise me if you haven't done
I appreciate your technical correctness. To be honest I followed your first roadtest articles series…
They are definately a great meter, an as you say you do get used to the size.
I do need to print out some cheat sheets, as I keep scratching my head and I know that xyz is possible.
I'm actually looking…
Hi Enrico,
Thanks! : )