Friday, October 28, 2016

Keysight U1282A Digital Multimeter - Review and IP67 Rating


I would like to thank Element14 and Keysight for selecting me to review the U1282A. Keysight, formerly Agilent Technologies, is a leader in electrical test equipment. While Keysight has been steadily expanding there multimeter offering, the U1282A is the newest in their lineup and first general purpose multimeter to be IP67 rated.

Unboxing and First Impressions

The U1282A comes nicely packaged as most of Keysights multimeters do. The overall presentation when opening the box for the first time is product built to be used hard and to last. The box comes with a built in divider to keep the multimeter separate from the accessories. The leads were neatly tied up in a ziplock bag unfortunately, there was no protection to cover their sharp points. The included test leads appear stiff and at the first chance I had, I swapped them out for a pair that came with my U1272A. Next to the leads was the IR-USB connector to allow for remote data logging as well a firmware upgrades. The inclusion of the IR-USB adapter is a much welcomed decision. As a good deal of problem solving is done over an extended duration being able to record data for that duration is a big help.

Unboxing the Keysight U1282A

Neatly folded on top of both the multimeter and accessories was the “Quick Start Guide” and certificate of calibration. It should be noted that if you ever lose your certificate of calibration and want a copy, Keysight has all the calibration data for each multimeter by serial number.

Reason for Application

I applied for the this road test because of my ongoing work reviewing new products. In this capacity the environments and issues and very wide spread. Some products work in or around water, making the IP67 rating very useful. Other products are supposed to be low power and having a second meter that can perform logging allows for DC power to be easily monitored. Still others are connected to mains power and the ability to quickly determine if the system is live or not can greatly increase the level of safety.

After watching Keysight’s promotional videos demonstrating their IP67 compliance I felt they were weak and unconvincing. Because of this I was very much interested in doing my own real world and maybe slightly exaggerated testing.


Another function I was interested in to exploring  was the PWM output. During testing there are times a servo or other PWM controlled device that may appear to not work. Having a known good PWM output can save many hours of troubleshooting. I as therefore curious to see if the PWM from the U1282A could be used as a test PWM for servos.

The last major U1282A function I wanted to evaluate was the Vsense. This function allows you to determine if a wire is live without making an electrical connection. This has the potential to make tasks a lot safer provided it works correctly all the time. Seeing as the number of inline devices or those attached to the mians are also increasing this would help increase the safety during my tests.

I should mention that there was never any intention to look at the accuracy of the U1282A as this is something Keysight is known for. I have only ever heard of one case where a new meter performed incorrect measurements. While this meter did have a calibration certificate this was probably a once of occurrence. I’m also sure that the are others that have reviewed the U1282A and have better means to test the accuracy and repeatability of the meter.

Sand Test

The first issue I wanted to cover was the demo videos from Keysight. As previously mentioned they seemed weak and unconvincing regarding true reliability of the meter. While Keysight did cover the meter is sand there was no attempt to move the selector dial or engage the meter in any mechanical use until after the sand was removed. Also the meter was at one point wetted before covering it with sand trapping the sand on the exteriors of the meter. This has the added benefit of reducing any penetration of sand into the selector dial and the connector terminals.

In the mentioned video the sand was promptly washed off after each time the unit was exposed to sand. In a real world situation we do not get to choose the order the meter is exposed to sand and water or how much of each. Also a bucket of water is most likely not readily available to wash off the sand before the job is completed. Whether it is possible to clean the meter or not, it would still need to be used and function without issue. It should be noted that washing off the meter would render it inoperable until it is dry due to the input warning (leads in wrong input).

In the testing I conducted the meter was completely covered with beach sand. While this may be finer than some sand commonly found, this is with in the size specification for the IP rating. This grain size would also have the potential to be blown around by the wind and into the crevices of the meter making this a valid test. After being subjected to the sand the meter was than cleaned off. This included being brushed off,  washed off with a “hose” as well as rinsed in a bucket. The complete procedure, the meter being covered as well as washed off can be seen in the videos below.


Immediately it can be heard that here is a decent amount of sand in the dial. Even with the background noise of the water and wind the grinding is unmistakable. The meter was then thoroughly washed off in a bucket of water as well as with a squirt gun.


The meter can unmistakably be heard being ground away by the sand stuck between the selector dial and the housing. While it may be considered slightly unfair to operate the selector dial while not completely cleaned from sand, this would most likely be done in a real situation. It should be noted that even with the wind in the background the sound is unmistakable. Also while the Keysight test appeared to show no sand in the dial after being washed off, this was clearly not the case here.

While this may seem like just an annoyance this could conceivably lead to product failure. Specifically this could lead to a breach of the housing allowing water or sand into the housing.This is clearly unacceptable for the IP67 standard, any interference with the satisfactory operation of the unit is considered an issue. The wearing away can be seen in the below picture. In this case the dial was rotated a few times (> 5) producing plastic filings around the AC volts and millivolts section of the dial.


Unfortunately there were only two available solutions to remove the sand. Either send the unit back to Keysight for cleaning or void any calibration warranty and clean the meter myself. Thankfully Keysight took the issue seriously and decided to consider this an “out of the box defect”. In this case the unit was repaired under warranty. I would like to mention that while this issue was being addressed by Keysight internally there was little consensus as to the classification of this issue. The product manager as well as the local FAE appeared to agree that this level of damage to the product should not occur. In contrast the design and test team appeared to be of the opinion that the testing I performed was not valid and the unit behaved as it is designed to and in accordance with the IP67 rating.

I have checked with the respective team, and we found that it is an expected behavior that the sand may ingress between the rotary switch and the top case. However, the sand will not go inside PCA level of the meter. “

After asking for further clarification due to the grinding of the plastic I received only instructions on how to send the unit back. There was no further information on how the plastic would not be ground down potentially causing a hole in the casing.

Water Test

The water test conducted by Keysight was for the most part sufficient. The meter was submerged and shaken around allowing for water to flow all over the unit. It is true that the meter was not submerged for the required 30 minutes but that was less of a concern considering others have put the meter through that testing. Also with regard to the water tight seals on the unit I don't believe I could do a better test than that conducted by Dave Jones. In his test the meter was submerged, dropped and abused in a very wet and demanding environment. Through all the testing the meter continued to work as designed.

What I have done different than all other water tests to date was to submerge the unit with all input terminals plugged with a test probe. While this would normally not be done and it does sound the input warning alarm, it was done to keep the water out of the terminals. Something I have mentioned to a number of Keysight personal (sales reps, FAEs etc.) is that plugs should be included in the kit or at least be available. The reason is that although the unit is waterproof the input warning will sound until the inputs are fully dry. While the IP67 rating ensures I will not damage my meter if it falls in water or gets wet my testing will be on hold for ~45 minutes or more until the probe terminals are completely dry. Keysight does ship their meters with dust plugs for the test leads and probes, which are sealed when in the field. in contrast to this, there are always at least 2 terminals left open to the elements for dust and water to get in, something is not making sense in this decision.

U1282A with all terminals capped while the meter is submerged

Test and Results

After inserting a lead into each of the 5 terminals the unit was submerged and splashed around a bit. The unit was turned on, the selector switch was rotated. While the unit was on the input warning sounded as expected. Once the water portion was complete the unit was taken out of the bucked and an air hose was used to dry the area around the leads.

When the extra two leads were removed the input warning did not sound. This was tested in all three variations. That is in volts, milliamps and amps mode, in all cases when the leads were inserted correctly the alarm did not sound. This furthers my question why Keysight does not include plugs with the unit for those doing testing in a wet environment.

Customer service

As mentioned above testing the unit in a sandy environment resulted in the selector dial becoming contaminated with grit. Since this was a road test Keysight was looking to keep things as positive as possible. Also because the issue was reported within 30 days of receiving the unit they decided to treat it as an out of box defect.

Unfortunately the process for taking care of this was a little bit convoluted and complex. While I was offered upfront to have the unit repaired I was hoping to get more info on the IP67 rating. This additional information never did come and there is still no clarification on what he unit should or should not be able to handle.

Experience with the return

Part of the reason for such a delay in this review has to do with the repair customer service. The amount of time it took to contact the product manager or anyone that could/would seriously help me was pretty extended. The product manager then needed to contact Malaysia and as well as the design team. Eventually I was informed Keysight would cover all cost in having the unit repaired. I was graciously offered to have the unit picked up from wherever was convenient for me, at home of from the office did not matter. In order to speed up the process I had it picked up from my home as this was closer to the sales representative and would allow for faster pick up.

While the unit was picked up the same day that I was contacted by the local office the whole process in having the unit repaired took substantially longer. I the unit wa shipped back to Malaysia where it was disassembled and cleaned. Then the unit was shipped back to the local office and than to me. In all the process took 6 weeks and 5 days (June 23 - August 9). For a piece of test gear that I would potentially use daily on the job, being without it for almost 7 weeks is unacceptable.

PWM Control (Servo Control)

Having a known valid PWM output is very handy especially when testing parts sent to you for evaluation. As a product tester/evaluator I test various products and devices. One of my recent projects was a robotic hand with 6 DoF. Unfortunately there was an issue with the servos not working as they should. Using the U1282A as a calibrated and valid PWM source made it a simple matter to test whether the issue was the servo or the controller.  

For this setup a 5V supply was connected to the power and ground leads on the servo. The U1282A was connected to the signal line and ground. The servo responded as expected it should with a valid PWM signal. This demonstrated the ease with which a PWM device could be debugged with the meter.

Video of meter controlling servo and scope showing changes of width

Since some servos still demonstrated some issues, the PWM output was connected to a oscilloscope. This again verified that the output appeared to be correct. The U1282A was also connected to a U1272A which has a frequency counter as well as a PWM deconstructor. This outputs the duty cycle as well as the period. Sadly the numbers displayed by the two meters had a significant discrepancy. After mentioning this to Keysight I was informed the U1272A needed a factory reset (not sure how this affects measurements but… ). This sadly did nothing to help remove the discrepancy.

Video of meters showing different numbers


The last major function of this meter that I was intrigued by was the VSense. This functionality allows you to test if a AC wire is live without needing to make contact. When working with live mains this is a major benefit. From testing inline IoT devices to troubleshooting a water heater this can seriously save you.

Before I got a chance to really test this functionality I found that my water heater was not behaving correctly. As part of the troubleshooting I wanted to be sure the heater was powered. When measuring the voltage between what appeared to be the two terminals a very low voltage was observed (~ 1V). Thankfully before working with anything I tested the circuit with the VSense and found there was still something live. On further inspection only one breaker was fully tripped. The second pole was still connected and was thus allowing something to creep through. I may not be 100% how I measured ~1V while the system was live but I am sure that without VSense things could have gone a lot worse.

I would like to mention that getting the VSense to behave predictably takes some time. When doing some of my further testing I found that there is a need to move the meter around slowly. This is because the sense location does not appear to always register in the same location. Also there are times you will need to change between high sensitivity and low sensitivity to be sure you are measuring the correct wire. Overall though the functionality is very useful and beneficial.

Recording Measurements

Another feature I wanted to look at, indirectly linked to the meter was the ability to log data remotely. Although this is not unique to the U1282A, the U1282A does put an emphasis on data logging. I have used previous iterations of Keysights data logging software with my U1272A with mixed results. While the update was relatively reliable things got worse when trying to log data. There were often times a value or multiple values were missed. Also, in previous iterations only one meter could be used at a time necessitating opening multiple logging windows. Having multiple windows compounded with missing data made the post processing very messy and and difficult to get usable and meaningful data.

In the newest version all these issues appear to have been taken care of. You can now connect to and log from up to 9 meters at the same time. There is also an easy way to either view the history of the data as a graph or as a meter display. The export function also works better than before, giving more options. Like Tektronix, Keysight appears to be realizing that good and easy to use software can be just as important as good hardware.
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Keysight PC based remote logging software logging from two meters

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The profiles of the connected meters as well as information on how they are connected


Overall this is a solid meter that as most if not all Keysight meters do, delivers good quality and is easy to use. Unfortunately from the IP67 rating as demonstrated by Keysight there is room for improvement or clarification. Most importantly the customer service experience needs a lot of help. Waiting 7 weeks to have a meter repaired is unacceptable.

If someone is looking for a meter that is reliable and delivers sound measurements, than any Keysight meter will do. The chances are someone would be choosing the U1282A for its IP67 rating. In that case I would differentiate between the IP6x and the IPx7. From the testing conducted by Dave Jones on the EEVBlog as well as my own basic testing I would say the U1282A is waterproof without an issue. Any environment that contains moisture or water the U1282A would work well in provided the unused terminals are covered. However, regarding the dust proof rating there are issues. The meter definitely has the ability to fail and the lack of clarification from within Keysight on what the meter should be able to withstand is also an issue. Lastly when the promotional video for Keysights version of IP6x involves covering the unit in sand, there should be no negative effects in doing so.

Based on these conclusions, for a wet environment I would recomend the U1282A but I would like to see Keysight add terminal dust caps to prevent water rendering the unit useless until completely dry. Unfortunately if the intended use is in an environment that contains fine grit sand (beach or desert sand) I don’t belive the U1282A will deliver what Keysight wants you to believe it will.


This is a response from Keysight in relation to the delay I experienced in having the unit serviced: The repair delay you experienced wasn’t representative of typical handheld repair. Normally you’d call in, ship the unit to our local service center, it would be exchanged and you get a new one back. Due to your IP67 questions and concerns, your unit was picked up by me, returned to the factory in Malaysia, analyzed, repaired and returned which was not the normal process.  We took your feedback very serious.

Original post on Element14 can be found here

Wednesday, October 5, 2016

Home Automation Using the Sonoff TH & SV - Review



With home automation expanding faster than ever thought and new products constantly coming out the DIY space is increasingly getting bigger as well. One of those companies joining in the DIY space is Itead Studio. About 10 months ago Itead Studio came out with their Sonoff and Slamphor solutions and have quickly built on these two platforms.

Recently Itead Studio brought out two new home automation products that complement their current products. The Sonoff TH allows the user to automate a devices on/off control based on either temperature or humidity. The other product recently introduced is the Sonoff SV. This Sonoff works off DC voltages ranging from 5V - 24V.

The Sonoff TH was added to support common residential devices such as fans and  humidifiers. The Sonoff TH currently only allow the connected device to be switched based on either temperature or humidity, not both.

Hardware overview

The Sonoff TH and SV internals have for the most part not changed very much from the original Sonoff. They still use a a 250V and 10A relay to do the switching on and off of the main power. The WiFi controller is the very popular and well used ESP8266EX. The onboard memory has been changed from Winbond to another company but I assume the general operation remains pretty much the same.

The main differences between the Sonoff TH and SV is in the power circuitry. With the TH needing to step down from 120V ~ 240V to 5V there is a transformer a bridge rectifier as well as other components to help stabilize and smooth out the incoming voltage. The Sonoff SV does not use mains voltage but rather uses 5V ~ 24V and as such only has a step down voltage regulator that outputs 3.3V to power the ESP8266.

It is interesting to note that both the TH and SV appear to have a location to connect the 433MHz RF module even if the code is missing to utilize them. Also the SV which should only operate 5v ~ 24V has the same track layout and spacing as the original Sonoff and TH.

Inline installation

Setting up the Sonoff TH is relatively simple for anyone with basic knowledge of AC electricity. The most complex part is knowing which of the spliced wires in neutral and and which is live. A quick search will show that (at least for North American plugs) the large prong on the plug is neutral and the smaller one is live.

I say large and small prong because a decent number of home appliances use two unmarked conductors. This leaves the the only way to know which is neutral by looking at he connected plug. This leads to an ongoing issue with the Sonoff devices, lack of a third pin. With more devices including a ground connection, not having this connection leads to messy and possibly dangerous wiring. Currently the only workaround would be to leave the ground wire uncut and wire it around the outside of the Sonoff.

Sonoff TH with only two connections, live and neutral

The Sonoff SV does not have this issue if used in the DC only mode. The Sonoff SV is a bit more involved in the connections however as there is no terminal block to easily connect wires too. The Sonoff SV needs the DC leads to be soldered directly to the board or terminal blocks added first.

Sonoff SV without terminal blocks

Sonoff Setup

In a previous blog the steps needed to connect the Sonoff as well as connecting to the desired WiFi acces point were covered. This was mainly done due to a lack of clear instructions for those wishing to do so. Thankfully Itead Studio have updated their Wiki to not only include clear steps but GIFs showing what each LED setting means.

With the addition of these two new devices the pairing has become clearer. This was done by having the Android App take you through each step needed. You start by clicking the “+” at the bottom of the home screen to start the adding process. Once done the the app asks you to be sure the Sonoff is in pairing mode and shows you what the state of the LED should be. Then the app asks you to choose a WiFi access point and input the password for that access point. The app will then look for all devices in pairing mode and within range. Once the app has found the device, passed along the WiFi credentials and registered the device with your account you are asked to name the device. Once named and you have confirm that you have added the device correctly the Sonoff is ready to be used..

The steps taken to setup the various Sonoff devices

This is a lot clearer and simpler than the previous suide steps provided with the previous versions of the app. The only issue that persists with the e-WeLink app is the way the password for the WiFi access point is handled. I had mentioned in my previous post about 10 months ago the issue with the WiFi password being stored in plain text. I also brought this up with my contact at Itead Studio and I was informed this would eventually be changed. But as can be seen this has not be taken care of as of this writing.

Connect to WIFI

The WiFi connection between the Sonoff and the router has so far posed no issues. I have tested a few scenarios of power outages and power cycling as well and so far have experienced no issues with the Sonoff not coming back online.

The explanation of the LEDs on the Wiki have definitely increased the understanding of what state the Sonoff is in. The LEDs have also reduced the number of questions regarding how well the Sonoff is working. Overall it feels that the reliability of the WiFi connection has been increased or at least maintained from the original Sonoffs to this newer version.

App Experience and Updates

Itead Studio has also update the overall experience of the app and not just the device pairing portion. The interface is much cleaner and better organized. It is now possible to clearly see more than four or so devices in a single screen as well as the state of the device (on/off). Also updated is the ability to affect the state of manually controlled devices from the home screen. Previously one needed to tap into the device to change its state. With the newer app, this can be done by tapping the device symbol on the home screen. Also updated is the state notification. Previously there was simply a green “LED” to let know if the device wa son or not. This has now been changed to having the hole device row turn blue when on and grey when off. This makes it much clearer as to what the state of a device is at just a glance.

Old vs. New App

The Sonoff TH has another nice feature. When you tap into the device the current temperature and humidity reading are presented at the top. Not only does this allow you to know what the current conditions are in the area around the Sonoff TH but it also help you set the conditions for the Sonoff. By knowing the current conditions you determine if those conditions are what you want to change the state of the device or a slightly higher/lower setting be preferable.

Sonoff TH Device Screen with Real Time Temperature and Humidity Data

The setup of the Sonoff TH is pretty simple. After tapping into the device you are presented with the device settings. On this page you can change from manual to auto settings. . When you change from manual to auto a setup screen pops up. On this screen you can choose between temperature and humidity through two radial buttons. After selecting wich parameter to use you set the above and below values.  As an aside if the auto/manual button was bigger it would be easier to use. After tapping OK the device will act according to the setting selected.

Setting Threshold Temperature/Humidity Values

The Sonoff SV is simpler as it only has a manual on/off button. It should be noted that both of these devices also have a the timer as well as a countdown feature. The countdown feature allows you to set an amount of time after which the device will either turn on or off.

Sonoff SV device screen

The timer function allows you to set up to eight different times at which you want the device to either turn on or turnoff. Considering a regular timer costs over $20 CAD this a big deal in itself. This is handy for someone leaving their house or wants something like a phone to charge for a specific amount of time.

Sonoff timer screen

There is one more overlooked setting on all the Sonoff devices, that is the power on state. This allows you to set the state the Sonoff when the device powers on. This is useful for power outages or other issues such as someone inadvertently unplugging the device. In this case you can set the device to be on/off on power up.

Sonoff settings screen

A new feature with the updated app is something called Scenes and an extension of this called Smart Scenes. A scene allows you to group various devices and set the state as you wish. This means you can have a bedtime scene were your room lights turn off, your bedside lamp turns on etc.  Previously you could choose to have various devices all on or al off, this new Scene allows different states to be set for each device. An extension of this that is currently only available on the Sonoff TH, Sonoff, Sonoff RF, Sonoff SV and Smart Socket. In this Scene you can set the temperature above which the other devices should turn on. Hopefully this will be expanded in future iterations to not just have devices turn on but, also off as well as have different states change. If the addition of humidity control was also added the functionality would be completed for this extended Scene capability.

The only downside that with the app has already been mentioned. That is the way the WiFI password is handled. Hopefully after writing about this in two blogs Itead Studio will try find a fix so that the password, once entered, is not visible to anyone picking up your phone.

Power Consumption

Power consumption of both the Sonoff TH and the SV were attempted to be measured. This is relevant as these devices are meant to be left plugged in or connected to a power source at all times. The Sonoff TH was connected to a MCP39F511 from Microchip. This was used as it has decent reliability and I no longer have access to a PA1000.

MCP39F511 power measurement kit

The measurement from the MCP39F511 was between 0.4W ~ 0.67W. Comparing this with a previous measurement using the PA1000 for the original Sonoff shows the two are similar. The previous measurements appeared to average around ~0.54W but with the high and low ends in the same region.

The Sonoff SV was in the process of being setup to be measured when the unit stopped working. While the cause of this is unclear one thought may be the lack of reverse polarity protection. With no terminal blocks the connections are made either with older or by adding terminal locks. In my case neither were used instead breadboard wires were used. A miss connection may have lead to this issue.

Due to this I was unable to take power measurements for the Sonoff SV. If however it is the same regions as the original Sonoff this could cause an issue. With the SV presumably intending to be connected to a battery device, 0.5W could drain a sizable battery in just  matter or days if not hours. I would hope this to not be the case and hopefully I will be able to do these measurement in the future and update this blog as accordingly.


The Sonoff have proven to be great group of devices that are both easy to use and install. They allow almost anyone to setup their own home automation system and to control their home in away they they see fit. There are however a few concerns. The first is with updates of the software on either an Android or Apple phone. I have repeatedly be asked to upgrade but not through Google Play. while some people might not think much about this, to me it poses a security breach that I prefer to not open.

Another security concern is the accessibility the E-Welink app wants to the phone. Previously the app wanted access to the camera, WiFi information, Device ID etc. In the most recent upgrade the app wants access to the microphone, SMS and it it already has access to your location and call logs. Again some people may not think much about this but, such overreaching access to information in concerning and unwarranted. It should be noted I have NOT upgraded to the most recent firmware. I may rather find a new way to use devices that frees me of the constant monitoring by unknown and possibly untrusted parties.

eWeLink “NEEDS” access to ALL these services....

Another security issue that has previously been mentioned but can not be stressed enough is the way the WiFi password is stored. Overall eWeLink has a lot of access to your phone and information. Unfortunately from what has been seen so far Itead Studio has not done much to secure this information or to show the user that this information is not being misused.

The another issue which has since been rectified for the Sonoff TH but not the Sonoff SV is the lack of cases. Without a reliable case the potential for an electric shock or shorting between conductors is always present. This presents a risk that a lot of people would not be willing to take if they young children or pets around.


Overall the Sonoff product line has been expanded in a useful way. These two products really allow for a wider number of devices to be connected to the IoT easily. While there are some things that Itead could improve with their app the overall experience is very good. The simplicity with which the Sonoffs can be installed really makes home automation something that anyone can do.