Siglent SDS1104X-E and SDS1204X-E Mixed Signal Oscilloscopes

[Rerouter]

Some more command Info,

To dump the full decode memory use the command "DCLR", you have 2 options, "DCLR? HEAD" which looks to scrape the length of the decode table, and "DCLR? DATA" which dumps exactly what you see on the decode list (whitespace and all), with the entry number and timestamps.

I've dug furthur into the DeCo_PAram Command, It has keywords (BUS,LIST,FOMT,LSSC,B1LSFN,B2LSFN,LSMN) but not yet clear on what data should be passed for each.

Next up, the decoder commands, these commands are used to setup a decoder via SCPI, they have query's but they are set to return 1, so my best guess is the queries are "To be developed later",
B1:DCCN (Can Decoder for Bus 1), has the Keywords (DIS,CANH,CANHT,CANL,CANLT,SRC,BAUD)
B1:DCIC (I2C Decoder for Bus 1), has the Keywords (DIS,SCL,SCLT,SDA,SDAT,RW)
B1:DCLN (Lin Decoder for Bus 1), has the Keywords (DIS,SRC,SRCT,BAUD)
B1:DCSP (SPI Decoder for Bus 1), has the Keywords (DIS,CLK,CLKT,EDGE,MISO,MISOT,MOSI,MOSIT,CSTP,CS,CST,NCS,NCST,LMT,BTOD,DTLG)
B1:DCUT (Uart Decoder for Bus 1), has the Keywords (DIS,RX,RXT,TX,TXT,BAUD,DTLG,PRCK,STOP,IDLE,BTOD)

Now my feeling is for the Pairs, e.g. RX / RXT, RX is the input that channel is on, RXT is the trigger threshold for that channel. as for its full documentation, that may come later, just felt I would raise this as the decode buffer is something people have been after

[gamerpaddy]

Just fixed a bug i thought it wasnt a bug until i accidentally fixed it..
My scope was unusable under 10mv/div at 1x, lots of noise. i tought its a smps going full retard somewhere in my house, but i turned everything off and even put the scope on a USV.. still this weird noise
it consisted of 20khz and 30khz peaks, some more in the upper band at around -50..40dB
I tried calibrating, but it did not solve anything.   
Even shorting the probes didnt help much.
it looked like this:

I did this production mode hack back then, so i didnt wanted to do a firmware update.
But now i tried updating to the latest firmware since meh what could happen, it updated without problems, and even kept the hack active (the firmware from Aug/Sept 2018)
And the noise issue was gone, i was now able to go below 1mv/div and have a useable line on my screen. 

[mroek]

I have ordered a 1104X-E, hoping to get it next week. However, I have a question: This model has no real on/off switch, which I'm not a huge fan of. I guess it's because they want it to properly shut down every time (hence only a soft button), but an additional physical switch to remove power could still have been there. Just like the switch on a computer power supply.

So, what do you guys do? Leave it plugged in, or do you unplug it after use? Or do you add some external switch to cut power?

[tautech]

I have ordered a 1104X-E, hoping to get it next week. However, I have a question: This model has no real on/off switch, which I'm not a huge fan of. I guess it's because they want it to properly shut down every time (hence only a soft button), but an additional physical switch to remove power could still have been there. Just like the switch on a computer power supply.

So, what do you guys do? Leave it plugged in, or do you unplug it after use? Or do you add some external switch to cut power?

Welcome to the forum.

You certainly can add an external switch but use scopes soft button to turn it OFF first.....it needs a second or two to shut down its OS correctly.
If I'm not at my bench using test equipment it's OFF at the wall.

[mroek]

I have ordered a 1104X-E, hoping to get it next week. However, I have a question: This model has no real on/off switch, which I'm not a huge fan of. I guess it's because they want it to properly shut down every time (hence only a soft button), but an additional physical switch to remove power could still have been there. Just like the switch on a computer power supply.

So, what do you guys do? Leave it plugged in, or do you unplug it after use? Or do you add some external switch to cut power?

Welcome to the forum.

You certainly can add an external switch but use scopes soft button to turn it OFF first.....it needs a second or two to shut down its OS correctly.
If I'm not at my bench using test equipment it's OFF at the wall.

Thanks! Having the power properly cut when unused is obviously the best strategy, so I guess I'll just have to add an external switch, just to be on the safe side.

And thanks for the welcome as well! I'm an electronics engineer that hasn't really done any electronics in a great many years, but suddenly I got the urge to order a new oscilloscope. My TDS210 still works, but the data record length is laughable by today's standards. And only 2 channels as well. I also have an old Goldstar OS9020G, but it hasn't seen any use for at least 15 years. It just takes up space, and has no real purpose any more.

[tautech]

And thanks for the welcome as well! I'm an electronics engineer that hasn't really done any electronics in a great many years, but suddenly I got the urge to order a new oscilloscope. My TDS210 still works, but the data record length is laughable by today's standards. And only 2 channels as well.

Massive step up from a TDS210 and great you already have DSO experience. 
I'm sure you'll love your new X-E.

[Gege34]

M'y scope (1104) is on power strip with a switch. And I switch it off when I doesn't need it for a long time.

[Martin72]

I didn´t care that much of it, although I never understand why using a soft-button for power on/off....

[Rerouter]

Follow up on the SAG1021, Its Capable of a 6V amplitude, with a +-7V offset range, sadly its limited by the output op amp (u8), to +-4V max output before it clips, If one wanted to, they could replace the output op amp to get to +-5V, or replace and increase the supply rails to get the output to +-10V range with the same 6V amplitude limit. with no significant software changes being required, apart from the XML tag on the scope that tells the UI the min and max offset limits.

Also there is a 16 bit 1MHz Texas Instruments on the board that I cannot understand the purpose of, just generates a 7.5KHz square wave that drops off in amplitude when set to DC output.

[tinhead]

Follow up on the SAG1021

after deeper look one can see, it is SDG1010/25/50,  but with one channel and yeah different FPGA.

Also there is a 16 bit 1MHz Texas Instruments on the board that I cannot understand the purpose of, just generates a 7.5KHz square wave that drops off in amplitude when set to DC output.

on SDG1010/25/50 that TI DAC is connected to 4051 common input and from there "everywhere", all 8 outputs are used. On SAG1021 however exact the same, TI DAC to 4051, but only two outputs are used, both then buffered by TP1272 and then middle of the relais field. Whatever this circuit id doing - and there are other interesting things like resistor-jumpers here and there, i'm to lazy to reverse it, for now i think i will dump everything first.

[mroek]

I initally assumed that it would be possible to use all four channels to get two "poor mans differential probes", but after some research, I discovered that there is only one maths channel. That's a bummer, as I had hoped to use this technique to measure both H-bridges of a stepper driver simultaneously. I know this technique isn't exactly stellar on a modern DSO (as Performa01's review shows), but I think it would have been sufficent for this purpose.

Doing advanced math (like multiple FFTs or such) is clearly way too demanding, but something as simple as adding/subtracting two channel pairs would be entirely feasible. However, I doubt Siglent will be inclined to add something like this to the firmware. It isn't something that is often needed, I guess.

[mroek]

My 1104X-E arrived this week, and I've just played around a little with it. First impression is quite good, it was surprisingly heavy and appears quite well built. The probes doesn't have the same quality feel as the scope itself, though. The fan is unfortunately louder than I had hoped. It has no whine or anything (thankfully), it's just that it is quite loud.

I still wish it had two maths channels though, since that would allow usage of all four channels to function as two "poor mans differential probes". Adding that to the frmware would clearly be possible, but Siglent probably doesn't care.

[Martin72]

Adding that to the frmware would clearly be possible, but Siglent probably doesn't care.

Find it out...

Ask them about it, if nobody ask for it....

[mroek]

@Martin72: I've posted the question to the thread that Siglent support supposedly monitors.

But now I have a different question: On my brand new scope (SDS1104X-E) , if I short the probes and look at the measured DC voltage, it appears that especially on the 2V/div range there is a DC offset that is higher than I'd expect. On channel 1 for instance, it is around -125 mV, which I think is a bit too much. It is enough that you can clearly see that the trace is offset from the vertical position markers. The other channels are a little better, but all have a negative offset of more than 80 mV.

The other ranges seems to be a lot better, so why is the 2V/div range so "bad"? On my old Tek TDS210 I'm seeing around 15-20 mV (in this range), which is more in line with what I'd expect.

I've also tried running a self calibration, (which actually did improve the situation, because before doing that it was even worse). Am I just expecting too much here?

[Rerouter]

Did you run the self calibration with the probes unplugged. The self calibration works by setting the channel offset dac. Measuring the voltage and using that to figure out the 0 point and gain for all gain and attenuation steps. If you have probes plugged in at the time that will cause some errors.

Equally is the offset the same on different ranges. E.g the 500uV range.

[mroek]

Yes, I unplugged all the probes before running the self calibration. I'll run it again and see if it changes anything.

Not sure I understood your last sentence. Did you mean that the offset should read about the same on all ranges?

[tautech]

@Martin72: I've posted the question to the thread that Siglent support supposedly monitors.

But now I have a different question: On my brand new scope (SDS1104X-E) , if I short the probes and look at the measured DC voltage, it appears that especially on the 2V/div range there is a DC offset that is higher than I'd expect. On channel 1 for instance, it is around -125 mV, which I think is a bit too much. It is enough that you can clearly see that the trace is offset from the vertical position markers. The other channels are a little better, but all have a negative offset of more than 80 mV.

The other ranges seems to be a lot better, so why is the 2V/div range so "bad"? On my old Tek TDS210 I'm seeing around 15-20 mV (in this range), which is more in line with what I'd expect.

I've also tried running a self calibration, (which actually did improve the situation, because before doing that it was even worse). Am I just expecting too much here?

What Rerouter said plus be sure to have it running for ~30 minutes before Self Cal. After which if running latest FW you can have the Quick Cal turned ON to take care of any little temp drift issues.

Let us know if all that works as it should for you please.

[mroek]

I've had it running for more than an hour now:

Code: [Select]

/ # uptime
 01:12:12 up  1:12,  0 users,  load average: 2.13, 1.53, 1.41
And I've ran the self calibration twice in the last 10 minutes. Seems to change a little between each run, but still quite a bit more offset than I'm happy with. The "Quick Cal" is on by default, and the scope came with the latest firmware (and it's hardware version 04). It was calibrated at the factory in December 2018.

After the last self calibration, it still shows an offset of around -120 mV, as can be seen here:



I'm using averaging (in the Acquire menu) to more cleanly show the offset here.

[tautech]

I've had it running for more than an hour now:

Code: [Select]

/ # uptime
 01:12:12 up  1:12,  0 users,  load average: 2.13, 1.53, 1.41
And I've ran the self calibration twice in the last 10 minutes. Seems to change a little between each run, but still quite a bit more offset than I'm happy with. The "Quick Cal" is on by default, and the scope came with the latest firmware (and it's hardware version 04). It was calibrated at the factory in December 2018.

After the last self calibration, it still shows an offset of around -120 mV, as can be seen here:



I'm using averaging (in the Acquire menu) to more cleanly show the offset here.

OK, thanks.
I'll shoot tech support an email to make them aware of this.....maybe they have a new firmware in the making to address this offset.

One other thing, is your lab low on EMI noise.....just in case it's effecting the Self Cal could you run it again in another room please ?

[Rerouter]

Ok. Now i understand better. Your running up against the limitations of the ADC in the scope. 2V/div is 16V over 256 steps is 62.5mV per step. Or about 2 steps offset.

I did not yet work out the exact mapping of the offset dac. It should be able to trim in better than that

For curiousity open the web interface and send the query C1:DACC? You will get a 4 or 5 digit number back. Add about 30 to the number and send back the command "C1:DACC number" and see if you can trim it back to be dead on the 0 line.

Equally does the offset change between scope probe connected and disconnected.

[mroek]

@tautech: My lab has a few cellular units running that can cause some EMI, but if that was it, shouldn't the other ranges be affected as well? It seems only the 2V/div range has serious issues. I will however rerun the self cal in a different room and report back, as you requested.

@Rerouter: The number I got back from the DACC command was 9811, and by changing it to 9807, I got the offset to become around +7 mV instead of -120 mV, so a massive improvement. The value doesn't stick, though. If I change to a different range and then back to 2V/div, the DACC value also returns to what it was.

I guess that means the self calibration routine might not do a good enough job?

[Rerouter]

The only exact way i can phrase it is later firmware versions may tweak it.

The offset should be fairly consistant between attenuator relay steps. As that is when the offset dac changes range aswell

There is already some quirks on the fine gain. This may just be related. I suspect its using an immidiate value and not a average for the offset calibration steps.

Any change with the pribe plugged vs unplugged

[mroek]

No change between no probe and with (shorted) probe connected.
And I've also re-run the self cal in a different room now, but nothing changed.

[Rerouter]

And lastly. With the coupling set to ground. Do they read better or worse (suspicious procedure may have changed)

[tautech]

@tautech: My lab has a few cellular units running that can cause some EMI, but if that was it, shouldn't the other ranges be affected as well?

Dunno, we will hand it over to the product manager at the factory soon.

It seems only the 2V/div range has serious issues. I will however rerun the self cal in a different room and report back, as you requested.

Thanks

And I've also re-run the self cal in a different room now, but nothing changed.

Thanks again.

I guess that means the self calibration routine might not do a good enough job?

Maybe, the firmware of the Self Cal has been optimized before in an older FW version. A component change or something minor may have mucked the Self Cal up, they can have a look at it and find a solution.

Look, by bringing this up you are effectively on record as having reported it so if there is a problem with just your unit it will get sorted sooner or later, one way or another.
For now just use it and lets see what the factory works out about it.


Thanks Rerouter for helping us dig deeper into this.