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Author Topic: Who has ever used the rigol 1000z delay trriger function?It can work?  (Read 1372 times)

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Offline Albert6186

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There is a very useful function on the rigol1000Z for me . The delay trigger function. In the user manual , the function description is beow:

In delay trigger, you need to set signal source A and signal source B. The oscilloscope triggers when the time difference (?T) between the specified edges of source A (Edge A) and source B (Edge B) meets the preset time limit, as shown in the figure below. Note: Edge A and Edge B must be neighbouring edges.

]I want to use this feature to monitor my system. There are 3 sensors , and each one has a AD. I want to know the synchronization difference among the 3 sensors. So I need this rigol oscilloscope feature to monitor the AD trigger clock  about every 250 us. But I found that function can't work. I set the condition is when the time between two edge bigger than 50 us trigger. But I got nothing. When I use edge trigger , I got too many wave. Most of them smaller than 50 us. But occasionally ?I noticed a long time interval. I need this delay trigger feature to make sure the sensor ad trigger synchronization less than 50 us. Or, I need watch the oscilloscope for very long time , and still not sure I solved that problem.   

Who can help me?  I misunderstand the oscilloscope? Or ,is there any other method I can use for my circumstance?

 

Offline ebastler

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Hi Albert,

In principle, you seem to have the right understanding of the delay trigger function. But from your post, I am not quite sure on what situation you want to trigger. Here's what I assume to be the case, and how to set up the trigger mode accordingly:
  • I assume that both sensor signals you want to monitor have the same polarity. So you need to select the same polarity for "Edge A" and "Edge B", respectively. (Different from the example graph you posted, which I believe is from Rigol's manual?

  • If you want to see how often the two edges are further apart than 50µs, you need to set the Delay Type to ">". Then, on the next page of the Trigger menu settings (after pressing the down arrow), set Lower Limit to "50 µs". Is that how you have set up your scope?

  • Set the trigger mode to "Normal", because you only want the scope to trigger when it sees a valid trigger event.
If everything is set up correctly, the scope should trigger every time it sees two edges which are more han 50µs apart. If nothing happens at all, try reducing the Lower Limit, until the scope begins to trigger. I hope this will work for you!

 
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Offline TurboTom

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@Albert6186:

Actually the scope works exactly as you suggested: I fed two square waveforms to CH1 and CH2, one at 1000Hz, the other at 1001Hz. Then I set up the trigger as shown in the two attached screenshots and got a trigger every second when the delay between the two traces was between 98 and 100µs -- spot on I would say  :)

Cheers,
Thomas
 
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Offline Electro Fan

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One way to confirm things are working and generally set right (if you have a sign gen with two outputs) is set the two channels on the sig gen for square waves with different frequencies (for example 1 MHz and 2 MHz).  Use your cursors to measure the difference between edges of interest (make note of the difference).  Also be sure to select the right measurement icon for delay (Dly 1->2; not sure on the Rigol 1k series, but on the Rigol 2k series there are 4 of these to select different edge to edge combinations.)  Then while both square waves are triggered on the screen set the trigger type for Delay.  Then adjust the delay Time and watch the square waves; when the time value passes the threshold you will see one of the square waves lose the trigger. On the 2k series I'm using the trigger begins to show the effect when it's within about 20ns of the expected threshold (you can see the persistence flicker on the waveform).  Not sure if I explained this quite right, hope it helps. 

- as eblaster said make sure to get the edge polarities correct (you should be able to do rising to rising, rising to falling, falling to rising or falling to falling), and as TurboTom said it's pretty close to spot on.
« Last Edit: May 10, 2017, 05:07:42 AM by Electro Fan »
 
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Offline Albert6186

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Thank you all. Thank you very much.

I'm not sure this problem has relation with the scope crack. My original scope is DS1054. I cracked it , and now it is  DS1104Z and all feature enabled.

@ebastler , yes, The pic I post is the picture on manual , not my product. In the real environment , all the sensor trigger signal are all falling edge. My setting is just same as you said , and tried many times.
    1 set different edge trigger source, and set each trigger level ;
    2 select time limit 50us? and > ,
    3 set normal trigger
    But ,nothing happened.

@TurboTom. I'll try your setting. Your setting is different from mine. You use "<>", and I use">". May be software bug , so your setting can work , and my setting not.

@Electro Fan. In my system , each sensor has the same trigger frequency. They are all isolated from each other . I think I can't use different trigger frequency.
@Electro Fan.I think watch "persistence flicker" is a good idea. I'm not sure I correctly understand what you said "persistence flicker". I think you mean I should increase the time base(maybe several seconds). If the waveform are correct, the waveform is continuous  and no flicker. Or ,I should notice some gap or flicker. It is useful. I think this method is  qualitative analysis ?not quantitative analysis. My understanding is right?

I still doubt maybe the 250us trigger interval is too fast , and the scope do not have enough time to action. My ad trigger signal is generated  every 250us and never stop.

Hope your reply . Thank you all.
 

Offline TurboTom

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Albert,

I checked the delay trigger with all four possible relations and got the expected result everytime. So I guess it is working okay. My scope is also an "improved" DS1054Z like yours, Software 04.04.03.02, hardware 0.1.1, boot 0.1.2, firmware 0.2.3.11. Basically, it's running the latest available update package, the scope itself is about two years old. Please check your software version since Rigol recently corrected quite some bugs that might have affected the older revisions.

Cheers and good luck,
Thomas

Edit: P.S. I did another test with short pulses, 1.0001kHz 10µs on ch2 and 1kHz 1µs on ch1 (hence a modulation frequency of 0.1Hz). Then I set up the trigger as you require for your test. I selected infinte persistance on the scope to show the relationship of possible trigger delays that actually will trigger the scope. with that configuration, I took a screen shot. Please make sure that you choose "normal" sweep on the page where you can enter the delay.
« Last Edit: May 11, 2017, 05:40:35 AM by TurboTom »
 
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Offline ebastler

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@ebastler , yes, The pic I post is the picture on manual , not my product. In the real environment , all the sensor trigger signal are all falling edge. My setting is just same as you said , and tried many times.
    1 set different edge trigger source, and set each trigger level ;
    2 select time limit 50us? and > ,
    3 set normal trigger
    But ,nothing happened.

Thank you for confirming your settings. So, are you sure that situations with the two falling edges further than 50µs do actually occur? You could try gradually reducing the delay time until you start to see trigger events. (Or increase it, starting from zero, until the scope stops triggering.)
 
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Offline Electro Fan

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@ebastler , yes, The pic I post is the picture on manual , not my product. In the real environment , all the sensor trigger signal are all falling edge. My setting is just same as you said , and tried many times.
    1 set different edge trigger source, and set each trigger level ;
    2 select time limit 50us? and > ,
    3 set normal trigger
    But ,nothing happened.

Thank you for confirming your settings. So, are you sure that situations with the two falling edges further than 50µs do actually occur? You could try gradually reducing the delay time until you start to see trigger events. (Or increase it, starting from zero, until the scope stops triggering.)

I tried a variety of settings, both to see how short a duration can be and how long it could be.  I didn't find the limits but as the image below shows it is definitely possible to trigger on a delay greater than 50us.  (I happened to use rising edge to rising edge for my tests.)

At the other (shorter end), fwiw, I found that it's possible to come within about 0.1us but not necessarily on a consistent basis.  What I found was that at the short end the Acquire setting can make a difference.  Generally on the short end Auto did not find the optimum setting - it took some trial and error to find the best performing memory depth.

But for this particular requirement (greater than 50us) the memory depth didn't seem to make a lot of difference, although you can see that the Auto setting happened to pick 280k pts and it triggered on a delay of 74.8us.  (This was on a 2k series, but I suspect the 1k series will be similar in performance for this use case.)

To do this test I used a sig gen with two channels and used the Run/Stop button.  (I only used the sig gen as a way to experiment.  I realize it's not what the OP was using but it's an easy way to see if the scope and the settings are behaving as expected.  Also, the same basic experiment could be done with one channel from a sig gen by selecting the delay between the rising and falling edge, or the falling and rising edge of the one signal, of course.)  Similar to what eblaster mentioned, I think it's a useful experiment to clear the screen and set a delay threshold well beyond what you expect to trigger on and then gradually adjust the Time setting at the bottom of the Delay menu items and wait to see where the actual trigger occurs.  It's important to start at the "wrong" side of the threshold when experimenting with the Time setting because once the scope triggers in Normal mode it won't retrigger until you clear the screen with a reset of the Run/Stop button.  (At the short end the persistence feature can help qualitatively indicate you are getting close but it's probably not as useful at the long end.)

Once you are comfortable that the scope and settings are doing what is expected you can apply the technique with the appropriate DUT and settings for your project, of course.  Good luck!  EF

PS, just a subtle thing, while you can test the delay function with the rising and falling edge of a single signal, if you want the Dly 1->2 menu items to display the measured delay (as in the lower left hand area of the image below with the 74.8us example) you need to use two channels.  However, you could pretty easily get the same measurements (and more) just using the cursor measurements as TurboTom did above.  You could also use the width measurements for a single signal.  Sorry if this stuff is obvious, just trying to be accurate and complete.  Most usefully for Delay measurements, gradually adjust the Time setting at the bottom of the Delay menu items and wait to see where the actual trigger occurs.
« Last Edit: May 11, 2017, 07:48:59 AM by Electro Fan »
 
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Offline Albert6186

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Thank you very much! Thank you all .

Sorry, I didn't exactly describe the problem. The problem is sometime no trigger and some time too many triggers.  At first I think this feature can't work . So I did not carefully think about it.

Now, I draw the conclusion:

1 The delay trigger function can work in the 1000z scope including cracked 1054z;

2 Why my previous setting can't work?
    (1).Most of time, the real signal is below pic 1 .  The falling edge of channel 1  is before the falling edge of ch2 in the green oval.
     
     
     At this moment , when use > setting , the trigger often can't happened  , because the gap between two falling edge less than the setting.
    (2) Another circumstance is pic 2. When triggered , the falling edge of channel 1  is the red arrow pointed not the green arrow pointed..
   
     At this moment, the trigger happened too many times, because the gap between the two edge connected by the green line is bigger than the setting.

    So, sometimes nothing happened ,and sometimes too many waves just like edge trigger effect.

3 How catch the signal I care
     Use the setting "<>" , just like what @TurboTom did.
     The lower limit is 50us , and the upper limit is 120us. So,I can catch the abnormal signal in the red oval in the pic 3.
     .
     The lower limit in the pic 3 is 80 us that is just for debug.

By the way ,this function is very rare in many scope.  When I suspected the 1000z , I waned to buy a cheap second hand scope to test my idea.   But after I checked old Agilent_54622D , HP 54645 and  Agilent-54845A , they all do not have this feature ? despite the fact that 54622D and 54645 were both equipped with digital analyzer . 

 
« Last Edit: May 14, 2017, 01:19:41 AM by Albert6186 »
 

Offline ebastler

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Hey, great to read that you solved this, and that the DS1000Z now works well for you.
Well done; you were persistent and got to the bottom of this. It certainly is one of the more complex trigger scenarios!

It's a nice little scope, isn't it?  :)
 
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