OWON XDM1041 the unknown multimeter...

[theHWcave]

@Misk
For anything above 100K or so, you must use LOW speed. Secondly AUTO RANGE is not reliable at high resistance values. Try manual range.  Using this I can measure 10 Meg with good accuracy

It is very similar to capacity mode. I find that > 1000uF you have to use manual range or you never get a good reading.

[Kleinstein]

Pt100 is problematic with 2 wires. 3 wire mode is usually not supportedd by DMMs. Bendch DMMs usually support 4 wire mode - though it looks like the XDM1041 does not. With 2 wire connections it would be better to use Pt1000 instead of Pt100.

The accuracy of thermocouples is often nor very good, but the error is usually more like a percentage of difference to the room temperatur. At essentially the room temperature there is not much error from the TC itself. There can be some error from the connectors, from lokal temperature gradients. It is more the PT100 sensor that can have an offset-error.

[Misk]

@Misk
For anything above 100K or so, you must use LOW speed. Secondly AUTO RANGE is not reliable at high resistance values. Try manual range.  Using this I can measure 10 Meg with good accuracy

It is very similar to capacity mode. I find that > 1000uF you have to use manual range or you never get a good reading.

Thank you. I ask OWON support one week.  Finally I get a special firmware from OWON and the all problems are solved.

[davebb]

@Misk
For anything above 100K or so, you must use LOW speed. Secondly AUTO RANGE is not reliable at high resistance values. Try manual range.  Using this I can measure 10 Meg with good accuracy

It is very similar to capacity mode. I find that > 1000uF you have to use manual range or you never get a good reading.

Thank you. I ask OWON support one week.  Finally I get a special firmware from OWON and the all problems are solved.

Hi do you up load the firmware with the rs232 / usb port,
Can you please post the new firmware and is there a loader program , Thanks Dave

[davebb]

Hi Misk
Have you tested with a K-type probe to test the Temp,
if you have does yours read ok ?, do you get a jump in temp after its been on for 10 mins?
what version firmware are you now using
Thanks Dave

[theHWcave]

Pt100 is problematic with 2 wires. 3 wire mode is usually not supportedd by DMMs. Bendch DMMs usually support 4 wire mode - though it looks like the XDM1041 does not. With 2 wire connections it would be better to use Pt1000 instead of Pt100.

The accuracy of thermocouples is often nor very good, but the error is usually more like a percentage of difference to the room temperatur. At essentially the room temperature there is not much error from the TC itself. There can be some error from the connectors, from lokal temperature gradients. It is more the PT100 sensor that can have an offset-error.

Totally agree with that, although you can use 3-wire as I described in my previous post with REL to null the wire resistance. Unfortunately the XDM1041 ignores the REL value for Ohms when using the PT100.  With PT100 the error caused by wire resistance can be significant. My probe has 0.262 Ohm (2-way) wire resistance. Without REL, this adds to the resistance of the sensor. At 5 deg C, that causes an error of 13%, at 10 deg.C still 6.5%, 20 deg.C 3.3%. Only for >70 deg.C will the error be 1% or less.  So for high temperature measurements, the PT100 is usable in the XDM1041, for room temperature sadly not (unless you change the sensor wires to have very little resistance).

[theHWcave]

Hi Have you tried a PT100 to see if that works ok, does the meter still use the same temp in the HY3131 for 10min cal
Thanks Dave

I tested this today and as expected, there is no 10min cal cycle in PT100 mode

[davebb]

ok thanks
it would be good to know what this new firmware that misk has now got and if it still does this,
Thanks Dave

[theHWcave]

Yeah, same here. After I saw Misk's post, I send an email to OWON asking about it....  but no response (so far). I'll post if I hear anything

I did an interesting test yesterday using a Peltier element cooling an old heat sink = chunk of aluminium. I had a PT100, the unknown K-type I normally use for the XDM1041 and a known (RS-components) K-type which I use for my BM869S all attached to the same area on that heat sink.  Long story short, it seems as if the XDM1041 was much closer tracking the PT100 when it used the RS-components K-type. That one, RS stock# 409-4920  costs nearly £8 (incl. VAT) and is still only rated as +- 1.5 degC, so I'd imagine the unknown one to be much worse. Side note. To use the RS K-type (or other more professional sensors) you need a K-type adapter. I use the Brymen BKB32 for around £5 from Telonic

[davebb]

Good afternoon
Thanks for the info, i hope you do get a replay  from owon
i will get a PT100
Thanks Dave

[davebb]

Hi i have just connected 99.5ohm and am getting -000.6c and it does not change after 10min so yes i will have to try a pt100,
does the K type respond faster to temp change,
do you know what software we can use to extract and load the firmware ,

Thanks Dave

[theHWcave]

I mentioned a few posts ago that there is no 10min cycle in PT100 mode...
Responsiveness depends a lot on the packaging. My PT100 sensor end is encased into some metal housing (like a short 6mm diameter pipe). That protects it well but makes it slower to respond than both my K-types which have the naked junction exposed.

The RS-components 409-4920 K-type I mentioned before has a  response time of 0.1s (datasheet). The PT100 (also RS) has no response time listed in the datasheet.

I am somewhat surprised you went for a PT100 not a "reputable" K-type. Unless of course you measure mostly high temperatures or got a probe with really short and thick leads. 

No idea how one would load firmware. I suppose it is possible that a certain button combination gets the processor into accepting firmware sent over the serial port but so far OWON has remained silent...

[davebb]

Hi i have not yet got a PT100, yes i did read that you said your meter did not do the 10min, but as mine is v1.3.0 i would test mine.
i only used a resistor, i hope that we get new firmware that also fixes this,
Thanks Dave

[kwass]

Dave said:

Just stumbled across this myself on ebay.
I kinda like the look of it!
Shame it's not battery powered.

But mine is!  I took advantage of all the USB power stuff available for cheap and replaced the internal 5V supply with a Qi charged LiPo cell.  I used this https://www.amazon.com/gp/product/B07M6CRQ71/ Qi receiver on Amazon along with this https://www.amazon.com/gp/product/B08GWTBD3T/ charger/booster module.  I used a large Qi pad https://www.amazon.com/gp/product/B07PYQQ1R7/ that the meter fits nicely on and has an "active" green LED in front.

While not necessary I added a small voltage meter so that I could see the change state of the LiPo cell all the time through the back window I installed in place of the IEC socket.  Also I installed threaded inserts to make removing the cover easier.

While I keep the meter on all the time, when it's "off the Qi pad" battery life is around 10 hours at full brightness, measuring volts, using a 3000mAh LiPo cell.  If you reduce the brightness to the minimum setting, it will last a full day.

[theHWcave]

@kwass: what a great mod! Very nice.

Can you tell me where you got these threaded inserts from? The number of times I open mine would make this a worth-while addition...

[kwass]

I used M2 size threaded inserts https://www.amazon.com/gp/product/B07LBQFNQD/ and melted them into the mounting posts.  Just takes a second but make sure that they are level.  I used M2 screws from this set https://www.amazon.com/gp/product/B07W5J4WC9/, you'll need some flat washers to match the width of the recessed case hole.

[BugCatcher]

Hi kwass,

battery based is an excellent feature!
My private "MiniLab" is 1.4m x 1.4m. I had already a lot of trouble with interference from switched power supplies and a DECT-phone-base below the desk.
Do you really use the XDM1041 during active charging? Did you observe any interference from the Qi pad (e.g. high impedance measurements)?
Active Qi pad on a lab desk ... I would expect a lot of trouble!

[kwass]

Do you really use the XDM1041 during active charging? Did you observe any interference from the Qi pad (e.g. high impedance measurements)?
Active Qi pad on a lab desk ... I would expect a lot of trouble!

Yes, I do use it during active charging all the time and I've not seen any interference from the Qi pad at all -- even on high resistance (10M+ ohm) measurements and sub-uA measurements.  The Qi receiver ships with a stick-on magnetic shied and I've installed that behind the receiver coil, that might be helping a bunch.  Keep in mind that this meter has absolutely no internal shielding and it was designed with a switching power supply almost touching the main PCB and it works fine.

I thought that about the same potential issue before I started this project and did a bunch of testing before any modifications, just to be sure it would work fine.

No doubt the Qi pad adds a lot of noise to the local RF environment, but so do many switching power supplies on my bench that operate in the same frequency range.

[theHWcave]

A quick update. OWON has sent me a firmware update !
You need to install a special uploader program on a Windows PC, connect the XDM1041 via serial port, then point the uploader at the firmware binary, initiate the upload on the PC and turn the XDM1041 off and on. Obviously the meter sends a special message during bootup (when the screen shows the progress bar) to the uploader. The uploader detects this and sends the new firmware in chunks to the meter and then confirms whether it was successful. Instead of version 1.2, my meter now shows 20210525 (obviously a date) as a version

In the 1 hour playing with it so far, I have not seen anything really different. Maybe the meter redraws the screen slightly faster but I can't really vouch for that. I did test capacitance mode in auto range mode and it is as bad as before (need to use manual range for >500uF ) and the hick-up every 600s in KITS90 mode is also still there.
I have asked for a description of the changes and also if I can share the firmware. Will report on responses.

[davebb]

Hi
This is great news,
I hope that they do let you post it, i would like to try it , to see if it helps my High Temp reading
Great video ,looking forward for the next one,
Thanks for letting us know
Thanks Dave

[theHWcave]

A list of all SCPI commands for the XDM1041 as far as I have discovered and tested them

Regarding firmware 25052021: its has issues on SCPI. For some reason, the XMD1041 now responds to every command that isn't by itself returning something with the string OK\nOK\nOK\n  (the \n being new line control characters). It does that even if you send nonsense like "hello world".  I think that change is the reason that the DMMEasyControl Windows software you can download from OWON to remote-control their multimeters can't change functions anymore.  The SCPI commands still work but your software now needs to deal with that nonsense response. Therefore I would not recommend this firmware change.

[davebb]

Hi i have just been playing with my meter, i have been compering it against a Fluke 189 that my old work mate gave me as he has just finished work for good as he is now 70 years old he also gave me a load of crimp tools and 2c Metcal soldering irons and a box of tips for them, He said that there was a meter in the box , but i did not expect a fluke 189 in great condition, i worked with him 13 years ago, i have not seen him for about 8 years, so it is good to keep in touch by phone  ,
the owon readings for dc voltage and resistance are very close to the fluke but what i did find is the dc current reading was out a bit, at 10 amps it was reading about 400ma low,
could this be corrected in the firmware ?
I do love the new to me fluke 189, peaple are still asking £370-400 on ebay for them,
Thanks Dave   

[Kleinstein]

The 10 A ranges on relatively cheap meters and also with some of the better hand-helds can suffer from heating of the shunt. So especially at a high current applied for a longer time, the reading may no be very accurate with both meters. It may be better to compare the 10 A range at a low current, like 2 or 3 A. So less heating and likely a more accurate reading.

The calibration procedure can likely adjust the skale factor for the 10 A range. With a modern meter this is done in software an not with an old style trimmer. Usually the factory calibration should be better than 4%, even with an OWON brand. The calibration procedure may not be openly available and may effect other ranges too - so nothing one would like to call if not absolutely needed.

The 10 A range on the fluke may no be perfectly protected by the fuse, so it may have suffered over years of use. So while it is a Fluke, I would not call a reliably reference for a recalibration. It is no clear which meter is out more.

[davebb]

Hi
it is the owon that is reading low, not the Fluke, The Fluke is perfect, i did compare the meters at a low current,500ma and up, i have Klunkin load ,
The owon reads low on the current range from mili-amps to 10amps and with 10 amps the owon is reading 9.6amps 400mAmps and 200ma low on 5amps load, i can leave 10amp on it and it does not change so i dont think it is heat
Thanks Dave

[theHWcave]

How strange. My Owon was within 0.02% of the BM869S for DC current from 1A all the way to 7.5A (which is as high as I could test). The BM869S is rated to 0.5% for current  (same as the XDM1041 and the Fluke 189 for that matter).  From 500mA to 1A it was within 0.04% of the Agilent 34401A and from 1mA to 100mA witihin 0.02% of the Agilent 34401A

Even if we assume that the Fluke is reading 0.5% too high, i.e. it shows 10A when the true current is only 9.95A and the Owon 0.5% too low so that it would read the same current as 9.9, your result  of 9.6 on the Owon is way out of spec.

Also the XDM1041 spec says that for >7A you should measure for a max of 30 seconds with 30 seconds off afterwards. Especially if you are ramping up the test current slowly, say to test the meter in 0.5A steps, that heat & time limit is easily exceeded as heat is of course accumulative.  The Fluke has a similar time restriction but only for >10A I believe.

Kleinstein has a valid point here and hopefully nothing got permanently damaged during your earlier tests. To exclude heating effects you should run accuracy tests for higher currents from cold, both meters in series and off for some time, and compare the readings in the 1st 30 seconds.