Rigol DG4xxx Signal Generator - Burst mode BUG

[GonzoTheGreat]

I discovered two bugs in the burst mode of Rigol signal generators DG4062 and DG4102 and DG4162.

BUG #1:

Summary: When bursting 1-cycle square waveforms, the duty cycle of the output waveform suddenly changes from 0.01% to 99.99% between pulse widths 70µs and 200µs.

Steps to reproduce:
1) Set CH1 of your signal generator to the Square waveform (Period: 70µS, StartPhase: 0º, Duty Cycle: 50%)
2) Set the Burst mode of CH1 to (Type: N_Cycle, Cycles: 1, Burst Period: 1sec., StartPhase: 0º, Source: Internal, Delay: 0 ).

This will set your signal generator to output a 35µs positive pulse every 1 second (very low duty cycle).
(the pulse is 35µs wide because the duty cycle of the square wave was set to 50% and ½ of 70µs is 35µs)

Now, slowly increase the period from 70µs to 200µs using the Square waveform menu of CH1 (which I have highlighted above in green color) and observe on a scope how the polarity of that positive output pulse suddenly changes to a negative going pulse (the CH1 waveform inverts) 

Consequences:  If you had a PWM amplifier/load connected to the CH1 output of that generator, then it would blow up as the driving signal suddenly inverted its duty cycle.


BUG #2:  Several days later I have discovered another bug in the Burst mode.

Summary: When bursting 1-cycle square waveforms, the output signal suddenly disappears when the Burst mode Delay is rapidly decreased.

Steps to reproduce:
1) Set CH1 of your signal generator to the Square waveform (Period: 10mS, StartPhase: 0º, Duty Cycle: 50%)
2) Set the Burst mode of CH1 to (Type: N_Cycle, Cycles: 1, Burst Period: 100mS, StartPhase: 0º, Source: Internal, Delay: 89ms ).
3) Set CH2 of your signal generator to the same settings as CH1 was set above (it does not matter whether the output of CH2 is enabled).
4) Rapidly decrease the Burst mode Delay of CH1 from 89ms to 0ns (marked above in brown color) by using the numerical keypad + Enter and observe how the CH1 output pulses completely disappear for over 2 minutes.  Rapidly decreasing this Delay with the knob can have the same effect.
5) Watch how the CH1 output signal stays completely disabled, (even if the CH1 Burst Delay is increased to the previous value) until the CH1 output is cycled OFF and ON again, ...or the Burst mode is cycled OFF and ON again, ...or after ~138 seconds elapse.


Models affected (both bugs):
All DG4xxxx models running firmware up to v1.08 and v1.10.
I did not test these bugs on firmware v1.09 and above but other people did.

I would appreciate a confirmation of this bug from people running firmware 1.09 and above.

[OldNeurons]

I am on 00.01.09, and can not reproduce the bug you described.

[PA0PBZ]

This bug was not tested on firmware v1.09 and above, because these firmwares "downgrade" the 200MHz model DG4202 to the 60MHz model DG4062.

Please note that if you change the model to DG4162 before upgrading you will be fine. So it's either a DG4202 with the bug or a DG4162 without it.

[Teneyes]

I discovered a bug in the burst mode of Rigol signal generators DG4062 and DG4102 and DG4162.
Summary: When bursting 1-cycle square waveforms, the duty cycle of the output waveform suddenly changes from 0.01% to 99.99% between pulse widths 70us and 110us.

I can confirm this Bug on Software 1.08   Hard version 1.01  S/N <2000
Error occurs with any Number of Burst Cycles.
Error occurs with Burst period at least down to 400uS , could be lower.
Error occurs on Squarewave Period 73us or greater.

If on Square wave Frequency:
    No error Freq.  >=  13.87160718 KHz
     Error    Freq   <=  13.87160717 KHz
Any Ideas why the errors start at this boundary 

Below I show No error then flip at 73uS Square wave period.

Could this be related to the Npulse Bug reported Here

Shoud I go to FW 1.09??

[GonzoTheGreat]

If on Square wave Frequency:
    No error Freq.  >=  13.87160718 KHz
     Error    Freq   <=  13.87160717 KHz
Any Ideas why the errors start at this boundary 

I don't know why the bug starts at this boundary but I know that it happens at different boundaries for different models.
For example in the DG4062 model, the error starts around the 100us boundary.

[OldNeurons]

After my first reply to 'GonzoTheGreat' yesterday, I upgraded my DG4062 to firmware version 00.01.10 (previously 00.01.09), and tried again to reproduce this bug.
In my case, this occurs exactly when I go from square wave period of 196.6080µs to 196.6081µs.
This doesn't occur when using pulse as source signal, but rising and falling time of pulse on the DG4062 are much longer than square.

[GonzoTheGreat]

I upgraded my DG4062 to firmware version 00.01.10 (previously 00.01.09), and tried again to reproduce this bug.
In my case, this occurs exactly when I go from square wave period of 196.6080µs to 196.6081µs.

I appreciate your vigilance despite the initial negative result. 
I have edited my initial description of the bug to cover that pulse width.

[OldNeurons]

@GonzoTheGreat

Could you try to setup phase in the burst mode to 359.999° and let me know your findings?
In my case, from 40ns to 200ms time period, no change in polarity.

For sure, there is a bug, but if this could help ...

[GonzoTheGreat]

Could you try to setup phase in the burst mode to 359.999° and let me know your findings?

Yes, it is a workaround.
Using the SYNC output on the front panel is a workaround, too - if you do not care about the lack of amplitude adjustment.

[GonzoTheGreat]

I have discovered a second bug in Burst mode and I have added it in this post.

[OldNeurons]

I have discovered a second bug in Burst mode and I have added it in this post.

I received an e-mail this morning, from Rigol U.S. telling me that a new firmware release for the DG4XXX series in coming soon ...
By the way, I tried to reproduce this 'second' bug on my DG4062, FW 00.01.10, and cannot get it.
May be it's there, but will occur at different conditions that yours.

[GonzoTheGreat]

By the way, I tried to reproduce this 'second' bug on my DG4062, FW 00.01.10, and cannot get it.
May be it's there, but will occur at different conditions that yours.

I've updated the steps needed to reproduce the Bug #2. Please try it again with the new values.

[OldNeurons]

By the way, I tried to reproduce this 'second' bug on my DG4062, FW 00.01.10, and cannot get it.
May be it's there, but will occur at different conditions that yours.

I've updated the steps needed to reproduce the Bug #2. Please try it again with the new values.

I tried again with your conditions and various other conditions for wave period, burst period and delay.
Can't reproduce the bug...

[GonzoTheGreat]

I tried again with your conditions and various other conditions for wave period, burst period and delay.
Can't reproduce the bug...

Maybe it was fixed in your firmware version.  Let's wait and see if the user Teneyes can reproduce it.

[OldNeurons]

I tried again with your conditions and various other conditions for wave period, burst period and delay.
Can't reproduce the bug...

Maybe it was fixed in your firmware version.  Let's wait and see if the user Teneyes can reproduce it.

Here is a copy of Rigol DG4xxxx firmware revision list (latest one).
I don't see for the latest version anything related to the bug you are facing.

[GonzoTheGreat]

I have amended the steps to replicate Bug #2 again here.  Please verify it.

[OldNeurons]

I have amended the steps to replicate Bug #2 again here.  Please verify it.

Bingo !!!
Same here with firmware 00.01.10.
I also discovered another bug in the AM, FM, ... mode. I will come back later with the description but I think that this one was not present before I updated the FW some days ago.

Do you intend to report that to Rigol?

Edit: Not sure if it's a bug, but feel it's annoying. Try this:

- Preset -> Factory defaults
- Output channel 1 ON. You should have at this stage a 1kHz, 5 Vpp signal on your scope.
- Press Mod (default values are AM modulation, 100Hz, Sine, 100% modulation.
- Change Shape to any other shape (Square, Triangle, etc ...). The signal goes OFF.
- Press Mod 2 times, or press Output twice to get the signal back with the new shape.

[GonzoTheGreat]

Bingo !!!
Same here with firmware 00.01.10.

I applaud your patience.
Could you edit your older messages so new users skimming through this thread will immediately see that these bugs are replicateable ?

Do you intend to report that to Rigol?

No, I have difficulty communicating with them.

I also discovered another bug in the AM, FM, ... mode.

- Preset -> Factory defaults
- Output channel 1 ON. You should have at this stage a 1kHz, 5 Vpp signal on your scope.
- Press Mod (default values are AM modulation, 100Hz, Sine, 100% modulation.
- Change Shape to any other shape (Square, Triangle, etc ...). The signal goes OFF.
- Press Mod 2 times, or press Output twice to get the signal back with the new shape.

I'd say it's a bug, too.
My unit also behaves the same way as you described above.

[Teneyes]

I have amended the steps to replicate Bug #2 again here.  Please verify it.

Finally testing #2 bug
In order to better understand the Delay function in Burst Mode , I show below the Sync Out pulse on Ch. 2 of DSO
 Pix are:
    1. with 10ms Squarewave period and 100ms Burst Period
    2. with 10ms Sawtooth period and 100ms Burst Period 00 delay
    3. with 10ms Sawtooth period and 100ms Burst Period 20ms delay
    4. with 10ms Sawtooth period and 100ms Burst Period 50ms delay
    5. with 10ms Sawtooth period and 100ms Burst Period Maximum delay = 89.998ms

    6. with 10ms Squarewave period and 100ms Burst Period Maximum delay = 89.998ms,
        with Zoom to show 2ms reset time between bursts

    7. with 10ms Squarewave period and 100ms Burst Period 00 delay
         NO output on jump to 00 delay

Yes I can Confirmation the Bug #2 on FW 1.08

[Teneyes]

Do you intend to report that to Rigol?

No, I have difficulty communicating with them.

I think it is not possible to get any response on a report of a bug in FW that is not the Latest version of released FW

[Teneyes]

Same here with firmware 00.01.10.
I also discovered another bug in the AM, FM, ... mode.
Not sure if it's a bug, but feel it's annoying. Try this:
- Preset -> Factory defaults
- Output channel 1 ON. You should have at this stage a 1kHz, 5 Vpp signal on your scope.
- Press Mod (default values are AM modulation, 100Hz, Sine, 100% modulation.
- Change Shape to any other shape (Square, Triangle, etc ...). The signal goes OFF.
- Press Mod 2 times, or press Output twice to get the signal back with the new shape.

No confirmation for this Bug report on FW 1.08 , DG4202

[GonzoTheGreat]

Finally testing #2 bug
In order to better understand the Delay function in Burst Mode , I show below the Sync Out pulse on Ch. 2 of DSO

Why is CH2 even monitored?
It does not matter if CH2 output is enabled - see pt.3 in the replication instructions ...it only matters if the CH2 Burst mode is enabled.

[Teneyes]

testing #2 bug
In order to better understand the Delay function in Burst Mode , I show below the Sync Out pulse on Ch. 2 of DSO

Why is CH2 even monitored?
It does not matter if CH2 output is enabled - see pt.3 in the replication instructions ...it only matters if the CH2 Burst mode is enabled.

In order to be describe the second (blue) trace in the Display
"I show below the DG4000 Chan.1 Sync Out pulse on Ch. 2 of DSO. in order to show the delay time from sync output until the single pulse is Generated"

Yes I missed the #3 point, thanks
Yes I can Confirm the #2 Bug in the display below I show the loss of output as I set the delay to 0
I will modify my  previous post

I also observed that the Output comes back On after about 140 Seconds without any intervention
See display 2.
But again this is with Old Firmware 1.08

[GonzoTheGreat]

I also observed that the Output comes back On after about 140 Seconds without any intervention
See display 2.
But again this is with Old Firmware 1.08

Interesting, over 2 minutes....   
I have modified  the original description of the Bug #2 to reflect this.
I confirm this on my unit with firmware v1.08 but we still need to know if the output comes back after ~140sec with other firmware versions.

[OldNeurons]

I also observed that the Output comes back On after about 140 Seconds without any intervention
See display 2.
But again this is with Old Firmware 1.08

Interesting, over 2 minutes....   
I have modified  the original description of the Bug #2 to reflect this.
I confirm this on my unit with firmware v1.08 but we still need to know if the output comes back after ~140sec with other firmware versions.

Confirmed with firmware version 00.01.10.
Output comes back after a bit less than138s.

[GonzoTheGreat]

It would be good for Shahriar to show these bugs as a follow up on the DG4162 video that he did a while ago.  Maybe Rigol will take notice....
Is anyone here in contact with him?

[miguelvp]

It would be good for Shahriar to show these bugs as a follow up on the DG4162 video that he did a while ago.  Maybe Rigol will take notice....
Is anyone here in contact with him?

I believe member Hugoneus knows him well
https://www.eevblog.com/forum/profile/?u=8240

[OldNeurons]

Another bug.

Setup:
Rigol DG4062, firmware revision 00.01.10
Metrix MTX3293 connected to DG4062 channel 1 output.

All voltage measurements below are averaged values over 30s.

Steps to reproduce:
01- Let your DG4062 warm up for 30mn.
02- Reset it to factory defaults. 'Preset' / O.K.
03- Waveform / Arb / SelectWform / Builtin / Common / DC / Select / Arb
04- Switch ON Output Channel 1
05- At this stage, you should read someting close to zero on your DMM (60µV in my case).
06- Set 'Offset' value to 50mV. You should read something close to 50mV (50.033mV in my case).
07- Switch Waveform type from 'Arb' to 'Sine'
08- Switch Waveform type from 'Sine' to 'Arb'
09- Voltage, in my case, jumps to 55.555mV (5.5mV increase).
10- Set 'Offset' value to zero.
11- Switch Waveform type from 'Arb' to 'Sine'
12- Switch Waveform type from 'Sine' to 'Arb'
13- Voltage, in my case, goes back to zero (60µV in my case).

This "I don't know what" remains somewhere at 5.5mV for Offset values ranging from zero to 2.0000V.
From 2.0001V to 10.0000V, this "I don't know what" jumps to 30mV.
This jump corresponds to a relay status changing internally (you can here a click when going from 2.0000V to 2.0001V.

I am curious to read your findings.
Thanks for your feedback.

[Teneyes]

Another bug.
Setup:
Rigol DG4062, firmware revision 00.01.10

07- Switch Waveform type from 'Arb' to 'Sine'
08- Switch Waveform type from 'Sine' to 'Arb'

Let's Call this the Arb-Sine-Arb BUG
Yes I can Confirm it, FW 1.08
So Attached is Gif of these steps:
   1. Arb-> Sine -> Arb ,with Arb DC set =0.0mV. ,          frames 1-15
   2. ArbDC =1.0mV.                                                       frame. 16
   3  Arb -> Sine -> Arb BUT ArbDC comes back as 3.6mV.    frames. 17-45
   4. ArbDC = 0.0 mV  .causes a Step of -1mV to 2.6mv    Frame  37
   5 Arb-> Sine -> Arb  and offset back to 0 mv.                frames 38- 62

So it looks like the Sine Func corrupts the offset parameters for the Arb DC function.
Was it because my sine wave function changes DC relays?

[GonzoTheGreat]

I confirm the Arb-Sine-Arb bug with firmware v1.08

[GonzoTheGreat]

I noticed a fourth bug!

Namely, the SYNC output is not synchronized with the period of the waveform appearing on the OUT output generated with the "Harmonic" menu for certain 3rd order waveforms.

By "not synchronized" I do not mean a constant phase difference.  I mean a variable phase difference between the OUT and SYNCH outputs.  The phase fluctuates wildly - maybe even 100º   

Now, I am trying to figure out for what harmonic amplitudes this bug occurs...

[Tom D]

...The phase fluctuates wildly - maybe even 100º   

Maybe the climate of Antarctica is wreaking havoc on your unit? 

Tom

[GonzoTheGreat]

Maybe the climate of Antarctica is wreaking havoc on your unit? 

No, I have a good bon fire going.

Both of the bugs I have reported were replicated by others from warmer climates.
I'd wager the 3rd one will be replicated, too, once I post detailed replication instructions.

[Tom D]

Thanks, Gonzo. I was looking at buying one of these, so I've been following this thread with interest. Nevertheless, I'm somewhat perturbed by your findings - I'm sorry to hear that you are having issues. I hope that this is only a firmware issue that will be resolved fairly quickly.

Tom 

[Teneyes]

Thanks, Gonzo. - I'm sorry to hear that you are having issues. I hope that this is only a firmware issue that will be resolved fairly quickly.

It would be proper for Gonzo to modify the first post of this thread to indicate all bugs and in which Firmware revision the bugs exist and if the bug was corrected in later firmware . 

To be realistic, Rigol will evaluate a bug report and decide if it will be corrected.

I have report bugs, and only after 18 months and,
after the bug continued on to the next generation of devices and
Dave Jones highlighting the bug did Rigol correct it.

These bugs on this thread are small, so just but be aware of them.

[OldNeurons]

These bugs on this thread are small, so just but be aware of them.

I do not consider bug#1 as a minor one, but as a major one.

It would be proper for Gonzo to modify the first post of this thread to indicate all bugs and in which Firmware revision the bugs exist and if the bug was corrected in later firmware . 

Yes, good idea.
Gonzo, do you intend to do so?

To be realistic, Rigol will evaluate a bug report and decide if it will be corrected.

I have report bugs, and only after 18 months and,
after the bug continued on to the next generation of devices and
Dave Jones highlighting the bug did Rigol correct it.

Software is everywhere. In your car, your fridge, your oscilloscope ...
Testing and debugging a new software is time consumming and costs money.
Well, this is one of the reasons why some products are cheaper than other. They live factories before completion ... and final debugging is made by the end consumer.
O.K., in our case, I have no problem to live for a certain period of time with a product which is only 95% finished.
But, when end consumers take a part of their time to properly describe and report issues to the manufacturer, and when this go unanswered and without any corrective actions, then I start to have a problem, and this kind of situation will certainly affect my future equipments choices and recommendations ...

I also found on my side another bug, not a serious one, but too much for me ... At the end, I will need a kind of 'Warning list' attached to this device  .

I'll come later with a description.

[OldNeurons]

So, here it is ...

Description:
Signal modulation stops when modulation shape is changed.

Setup:
Rigol DG4062, firmware revision 00.01.10
Rigol DS2102A for signal monitoring.

Steps to reproduce:
01- Reset DG4062 to factory defaults. 'Preset' / O.K.
02- Switch ON Output Channel 1
03- Press MOD. At this stage, you should observe a sine signal with 100% AM.
04- Change SHAPE to SQUARE, TRIANGLE.. or whatever you want. At this stage the signal goes OFF.
06- To restore the signal, there are 3 solutions. Press MOD 2 times, or press OUTPUT OFF and ON, or change the AM Depth to a new value.

When AM Depth is different than 100% and SHAPE is changed, the signal freezes at low level of AM Depth value.

If carrier signal is PULSE, instead of any other, then when changing SHAPE or DutyDev in the MOD menu, PWM will stop. Same medecine than above applies to recover...

Still curious to get your feedback with same or different firmware version.
Thanks.

[GonzoTheGreat]

It would be proper for Gonzo to modify the first post of this thread to indicate all bugs and in which Firmware revision the bugs exist and if the bug was corrected in later firmware . 

Yes, good idea.  Gonzo, do you intend to do so?

I will do it.
I think all bugs replicable on firmware v1.08 and v1.10, correct?
I am a bit fuzzy about v1.09 though...

Also, do you want me to add the Arb-Sine-Arb bug to the first post ?

[OldNeurons]

Also, do you want me to add the Arb-Sine-Arb bug to the first post ?

Yes, sure, and also the last one "Signal modulation stops when modulation shape is changed."

[GonzoTheGreat]

Description:
Signal modulation stops when modulation shape is changed.

Setup:
Rigol DG4062, firmware revision 00.01.10
Rigol DS2102A for signal monitoring.

Steps to reproduce:
01- Reset DG4062 to factory defaults. 'Preset' / O.K.
02- Switch ON Output Channel 1
03- Press MOD. At this stage, you should observe a sine signal with 100% AM.
04- Change SHAPE to SQUARE, TRIANGLE.. or whatever you want. At this stage the signal goes OFF.
06- To restore the signal, there are 3 solutions. Press MOD 2 times, or press OUTPUT OFF and ON, or change the AM Depth to a new value.

When AM Depth is different than 100% and SHAPE is changed, the signal freezes at low level of AM Depth value.

If carrier signal is PULSE, instead of any other, then when changing SHAPE or DutyDev in the MOD menu, PWM will stop. Same medicine than above applies to recover...

I was not able to reproduce any part of this bug on firmware v 1.08.

[GonzoTheGreat]

I noticed a fourth bug!

Namely, the SYNC output is not synchronized with the period of the waveform appearing on the OUT output generated with the "Harmonic" menu for certain 3rd order waveforms.

By "not synchronized" I do not mean a constant phase difference.  I mean a variable phase difference between the OUT and SYNCH outputs.  The phase fluctuates wildly - maybe even 100º   

Now, I am trying to figure out for what harmonic amplitudes this bug occurs...

Here we go ...this behavior turns out to be a feature -  not a bug
Below are the steps needed to replicate this behavior:

1) Set the Rigol DG4xxx to factory defaults using the "Preset" button.
2) Enable the Ch1 SYNC output on the front panel using the "Utility" button
3) Enable Ch1 Output
4) Set Ch1 to the Harmonic mode using the "Harmonic" button (Frequency: 100kHz, Amplitude: 5.0Vpp, Offset: 0.0VDC, Start Phase: 0.000º, Order: 2, Type: Even,  SN: 2, Amplitude of the 2nd harmonic: 3Vpp, Phase of the 2nd harmonic: 0.000º)
5) Set your scope to display Ch1 output and SYNC1 output, while triggering on the SYNC1 output.
6) Slowly increase the Amplitude of the 2nd harmonic (shown in green color in pt.4) to 6.0Vpp and observe the loss of synchronization on your scope.

CONCLUSION:  The period of the rectangular signal at the SYNCH1 output is not related to the period of the harmonic waveform on CH1 output, unless you set the CH1 "SyncMode" to "Carrier" using the "Utility" button.

[Tom D]

Thank you for the updates, Gonzo - your time and efforts are much appreciated.

Tom

[OldNeurons]

I received an e-mail from Rigol U.S. one hour ago.
A new firmware is available (00.01.11) and I am waiting for it ...
It is supposed to be fully automated and should take a few minutes according the e-mail.
I followed step by step the procedure and ... nothing yet after more than one hour now. I am not very surprised since previously, I had to ask Rigol US and Germany several times before I got something.

If someone is more lucky than me, please let me know, and share ...

Thanks !!!

Edit : Link to the Rigol Web site
http://beyondmeasure.rigoltech.com/acton/form/1579/0012:d-0001/1/index.htm?id=0012