Siglent Bench DMMs SDM3065X, SDM3055 and SDM3045X

[Repro77]

I apologize if this has been covered already, or a known feature, but here is my question / observation.

I was measuring AC voltage using my DMMCheck voltage reference on my brand new SDM3055 (using the most recent firmware), and noticed an interesting measurement.

While in just AC voltage mode, it shows 04.9980 (dead on). If I change it to dual display mode, with HZ in the small window, the AC voltage shows 4.99802. One more digit, and it updates just fine.

I can post pics if needed, but is this normal? I didn't think it was capable of that on this unit....or am I missing something?

[tautech]

Yep normal as it displays the leading zero on the main display in some ranges.

It's been mentioned before as a waste of resolution and we'd all rather it didn't.

[Repro77]

As a 5 1/2 digit multimeter, should it be able to display a reading of 4.99802? Wouldn't that be 6 + (but no leading zero or one..?...)
...or just a quirk of this model / manufacturer?

[TheDefpom]

These are 219999 count meters, so really the 4.99802V reading shouldn't be possible, as it should be in the next range up (the 20V range), which would prefix with the 0 to show the range (although unnecessary), so this is likely an oversight in the firmware which gives you an extra digit for free... nice !

I just tested this on my 3065X and I have 6.5 digits regardless.

[Kleinstein]

The actual ADC inside has more resolution than what is displayed. This is especially true for the slower modes where likely several internal readings are averaged out. Some extra resolution is needed to use numerical cal factors instead of old style trimmers - so rounding artifacts are in the next digit not shown. It is the accuracy and reference that limit the useful resolution. So the extra displayed digit is more like a small software bug.

With modern DMMs it is common to get more resolution when reading the result to the PC. The display value should be limited to the digits that a reasonable reliable.

Often math functions can be used to display more digits, as here it is more difficult to cut extra digits.

[CDN_Torsten]

One of the 'features' I find strange on the SDM3055 is the 'Filter' function. 
Does anyone understand why when enabling the "Filter", the DMM reads higher than it does without the filter enabled?
I would have assumed that the filter would average/remove noise, not apply a DC offset.  It also seems that there is more 'noise' with the filter enabled...

[Kleinstein]

With DMMs there are 2 types of filters:  one is digital filtering, usually a running average over a given number of points. This should reduce the noise quite a bit and should not effect the value. A different value from a digital fitler would be a software bug.

The other type of filter is an analog filter, more at the input. This was especially used in some older more higher grade DMMs. This can improve the hum suppresion and reduce noise from aliasing somewhat. However the resistors involved may also add some additional noise. It depends on the signal and implementation if the noise goes up or down. Especially with a low noise signal to start with, the noise may go up.
With leakage / bias currents there may be some offset involved.

I looks a little like the SDM3055 seem to have an analog filter. When enabling the fitler one may have to call something like Azero once, to compensate for at least some of the offsets.
Ideally there should be not change in offset - but there is a potential for errors, e.g. from bias currents or a not so good calibration (e.g. wrong correction of a jump that is there in HW).
It is a bit surprising to find a switchable analog filter in such a more low cost meter.  Ideally the manual should explain what type of filter is implemented and what effect to expect.
With a SD ADC I would not not expect a very low frequency filter, so the settling time to the new value looks surprisingly long. An analog fitler would be more helpful with a classical MS-ADC or even more the recirculating reminder ADC (a sampling ADC) in some old Fluke meters. Because of the added costs and the settling time extra analog filtering is not very popular anymore, excepts for the more EMI part that is definitely needed.

[Ringmodulator]

The SDM3045X has a filter function for the DC ranges too.
It is not mentioned in the manual and probably came with a later FW update(?).

[CDN_Torsten]

Kleinstein - I agree this looks like a very analog filter.

I've done a few more tests at 100mV and 0V (input shorted).  In both cases there is an offset, and more noise with the filter enabled.

Is anyone else seeing this on their SDM3055??

[maxspb69]

SDM3065X, last firmware V3.01.01.08R1.

A bar meter,  that refreshes  1-2 times per second is completely useless! It must either be removed completely or it must be refreshed at least 15-20 times per second.

The "Power On - Last" option still does not work normally. The device sometimes turns on with default settings. Regardless of the state of the "Power On" option.
In fact, sometimes it works, sometimes it doesn't. And sometimes the device boots and immediately freezes (several times this happened in the continuity test mode)

And since Siglent copied the Agilent  interface, it would be good to copy the "Continuity test" function from Fluke. The minimum length of the beep sound should be fixed (0.25 sec for example) even if the circuit was closed for a very short time (a few milliseconds), as in many Fluke multimeters. The problem with the continuity test is not a low refresh rate, but that the duration of the beep signal is equal to the duration of the circuit closure. And it doesn't always work well. In my humble opinion, of course 

[maxspb69]

I seem to have found a way to solve most of the meter slowness issues. Try switching to an external trigger and applying pulses (positive, 100-500uS length),  frequency, for example, 15-20Hz, to the external trigger input. Switch on the continuity check mode and... you will not recognize your meter:  the response  will be instant and stable!

https://youtu.be/l6XR-P07voM

I think most of the slowness problems are due to serious bugs in the internal trigger signal generation. It is constantly interrupted, this can be clearly seen on the oscilloscope in the continuity mode and other modes with fast synchronization.
It is also worth noting that the bar meter in the EasyDMM program works very quickly, as it should. And on the meter screen  it is very slow, which is unacceptable!

There are also serious bugs in the "Trigger Delay" option  in "Acquisition" screen. The sampling intervals do not correspond to the  delay which setted and vary within 1 sec. If you set a delay of 1sec, then the real measurement interval will be 1.65 sec.
If you perform the same operations through the EasyDMM, then everything works correctly, because the trigger signal is most likely generated by a computer.

Everything above has been tested on SDM3065X, but I'm pretty sure it will work the same on 3055 and 3045X.

I believe that Siglent should solve this problem (unstable internal trigger  generation) in the first place, this will greatly improved all aspects of working with the meter.

upd: the screenshot shows the "ragged" internal trigger signal in the "Continuity" mode

[maxwell3e10]

It seems the resolution in statistics mode is only 5.5 digits. Most DMMs calculate statistics average to a higher resolution. Even switching the meter to relative mode does not improve it, even when the trend chart shows many digits.

[tautech]

Maybe you can get better results in EasyDMM IDK.

[maxspb69]

EasyDMM = +1digit No more.

[maxwell3e10]

Direct read over USB gives plenty of digits. So if EasyDMM doesn't show them, it's really a shame

[maxspb69]

About the so-called firmware "error correction" in SDM30XX: One gets the impression that no one at all deals with these devices in Siglent. The Chinese programmer sat down at the computer, corrected something in an hour, and posted it without testing at all. Because those "changes and bug fixes" that are announced in the new firmware are complete evil! Correcting something one, breaking something else. There are no real fixes. Global problems of this meters remain in them for years. And there is no longer any hope that someone will actually fix something, and will not issue a "new" firmware in a year, which does not fix or add anything.
Siglent has great oscilloscopes and AWG lately, but meters are crap, sorry. And nobody is worried about it in Siglent. 

I bought the SDM3065X a few weeks ago and am ready to throw it out the window for just freezing when working with a USB-drive. Not to mention the poor implementation of the registration function in general, the fantastic slow continuity test and the useless super-slow graphical bar meter. It can take a long time to list fatal errors...

Miser pays twice. There are no exceptions to this rule!

[CDN_Torsten]

maxspb69 - I think you hit the nail on the head.  This feels like an abandoned product line.... such a shame... it has/had potential.

[maxspb69]

A well-known problem with most Chinese equipment: good hardware, terrible software. This applies fully to Siglent meters. These would be excellent devices, if the firmware was made by professionals.

[CDN_Torsten]

Siglent has professional software teams - their other products show this.  This feels more like a business decision/resourcing issue.
Enough said...

[2N3055]

And since Siglent copied the Agilent  interface, it would be good to copy the "Continuity test" function from Fluke. The minimum length of the beep sound should be fixed (0.25 sec for example) even if the circuit was closed for a very short time (a few milliseconds), as in many Fluke multimeters. The problem with the continuity test is not a low refresh rate, but that the duration of the beep signal is equal to the duration of the circuit closure. And it doesn't always work well. In my humble opinion, of course 

That is funny how different people are different.

I absolutely hate Fluke latched continuity. I like real time, analog tone, that will be scratchy if contact is not good.
That gives me additional information of intermittent contact.. As they say, to each it's own...
Funny part is that meter could be made that could do both and have it user selectable.

[tautech]

Siglent has professional software teams - their other products show this.  This feels more like a business decision/resourcing issue.

Or a weak product manager.
It is the current topic of some discussion.

I bought the SDM3065X a few weeks ago and am ready to throw it out the window for just freezing when working with a USB-drive.

Please inform us of drive brand and size.

Your previous reports have been sent to Siglent just a few days ago as they have been on break for CNY.

[maxspb69]

USB drives: Transcend USB2.0 8Gb, Transcend USB2.0 16Gb.

Most often freezes occur when I trying to load a custom temperature sensor profile from a USB drive. And if the file is not in the root directory, but in some folder -  freezing occurs almost always.

Addendum: why does a 6.5-digit meter in "U-disk register" mode" write only 5 decimal places in 0.00000 format? Is this normal? 23.4654mV will be written as 0.02346V. On the contrary, the previous firmware recorded too many extra (false?)  digits, but did not record time stamps.

Interestingly, does anyone check this before publishing?

[Bad_Driver]

I'm following this topic for about 1 year because I'm looking for a new 6.5 digit bench DMM.
I have an old but very reliable FLUKE 45 but for tracking reference voltages of OCXOs the resolution is to low.

I'm pretty happy with my SIGENT SDS2000x+ and my SDG2042. So the SIGLENT SDM 3065 should have be a logic decision, if I wouldn't
have found this topic.

Possible alternatives I thought about were the Keithley DMM6500.
I appreciate the new approach with the UI but I think that I do not need all the possibilities and it is very very long and I have limited space
on my bench. The Keysight "original" 34461 is out of range for me, I set my limit for a DMM at a max. of 1k€.

The SDM 3065 is now about 6 years on the market and it seems to be from the hardware perspective ok but all what I read here with
the so easy to fix software problems let me hesitate.

In the meantime I bought a 20y+ old HP 34401a - rock solid, in spec and all what I need for long term logging I get with free software. And no boot delay! So I could spend some money for a second one and both together would be cheaper than one SDM3065...

It seems that Siglent does not take enough care of this product family and for that what I now get the device is overpriced (800€ in GER).
OK I can wait another year but if another affordable 34401a comes around I'll left the market as potential DMM buyer.

[tautech]

The SDM 3065 is now about 6 years on the market

From P1 in this thread:
SDM3065X Released April 2017

I understand your comments and yes it has been far too long to have these DMM's bug free however we are getting some quality feedback from buyers to help with this and you can be well assured tautech is pressuring Siglent to finish polishing these products. When they arrived back from CNY there was already mails from me waiting for them which if there is no action soon I will take to the highest levels. 

[Bad_Driver]

Hi Tautech,

I know that you are fighting everywhere to satisfy Siglent's customers. And I appreciate this! Sorry for making the SDM3065 older than it is but you got my point.

It's sad to see that such a good designed product (from HW perspective) suffers from insufficient efforts in software fixes. We all are happy with the quarterly fixes and improvements
with the SDS2000X+ series and many hobbyist are very loyal to Siglent (I'm going to buy a SAA this year). And a lot of people like me are keen to get a good affordable (new) DMM.

So thanks for your hard work but someone at Siglent should decide what the future of the SDM family shall be.

B.D.