How can i capture these two scenarios using Siglent 1104X-E - Page 1
Forum section: electronics / beginners

author: sairfan1
author_rank: Frequent Contributor
timestamp: August 17, 2021, 04:42:07 pm
content: I recently bought Siglent 1104X-E i want to capture some events, configurations are as followingSCENARIO 1:1. uC pin A goes low for a time and then gets back high, it is connected with trigger connector 4 on scope2. Trigger is set to fire on falling edge3. uC pin B is connected to scope connector 1 (or also named X)I want to observe what happens to the signal on pin B while pin A was low,it start reading on falling edge trigger but it happens so quickly that i could not stop and capture that event, (unfortunately it captures only those readings what i can see in the screen? i can only navigate time span that was on screen)Q: My question is just like i can trigger start on falling edge how can i trigger stop on rising edge?SCENARIO 2:1. uC pin A is connected to trigger connector on scope2. Trigger is set to on falling edgeI want to to capture first 100ms after the trigger firedI'll appreciate if someone can explain what other triggers are available on this scope and any other methods to deal with such situations

author: jmelson
author_rank: Super Contributor
timestamp: August 17, 2021, 05:46:37 pm
content: Not familiar with that model, but isn't there a single capture button? Set it to single, start and wait for the desired event to trigger it.It will only capture the first event that triggers it.

author: bdunham7
author_rank: Super Contributor
timestamp: August 17, 2021, 06:14:31 pm
content: You need to learn about and use the ZOOM (press your horizontal timebase knob) and SINGLE features before you go for advanced triggering techniques.

author: sairfan1
author_rank: Frequent Contributor
timestamp: August 17, 2021, 07:36:12 pm
content: QuoteThat's what I'm already trying, i set trigger on falling edge it starts sampling when trigger happens, but it keep sampling unless i stop it by stop button, but by that time, time span that i want to capture has gone out of screen (capture able area)QuoteYes I'm already using zoom functionality, problem is that what data i want to capture, happens right after trigger, within 100ms, by the time i press stop huge data has already sampled and that starting part that i want to capture has already out from buffer.let me explain it again.1. i set the trigger on falling edge2. now scope is waiting for the falling edge event3. scope got falling edge signal and start capture triggers4. scope start sampling5. i stop the scope, so that i can review the captured datafor example scope can capture a window of 500msby the time i press stop button 1000ms has elapsedi wanted to review first 100ms but they are not in the window/captured bufferthat's why what solution i was thinking of, could be:1. scope automatically start sampling on falling edge and automatically stop sampling on raising edge2. i can set some function in the scope that after the falling edge signal it should capture only first 100ms long data sample and then stop automaticallyif i can stop scope automatically by a raising edge signal or by time that can help me, I have no idea if some other method is used for same.

author: bdunham7
author_rank: Super Contributor
timestamp: August 17, 2021, 08:13:23 pm
content: You shouldn't need to stop the scope with a button push. Try things in this order:1. Get your signal up on the screen so that you can see it clearly and trigger on the first event that you want to trigger on. Don't worry about seeing the full 100ms or whatever at this stage, just get a clean, triggered, viewable signal. Note the timebase setting that gives you a good closeup view.2. Set the timebase (horizontal) knob to 20ms/div. You should see an indication in the upper right corner saying "50MSa/s" and "14 Mpts". Don't worry about what the signal looks like, it will probably be all mashed together.3. Press the horizontal knob in momentarily (you don't need to hold it), then adjust the zoom timebase to whatever you noted in step 1.4. Press the RUN/STOP button to freeze the scope. Then press the SINGLE button.The next time the trigger event happens, the scope will capture a full 140ms of data after the trigger event (as well as before) and display it all in what will probably be an unviewable mess on the top half of the screen. On the bottom half you will have a viewable waveform and you can scroll through it with the small horizontal position knob, as well as expanding/contracting it with the larger horizontal timebase knob.

author: tautech
author_rank: Super Contributor
timestamp: August 18, 2021, 03:02:27 am
content: Quote from: sairfan1 on August 17, 2021, 07:36:12 pmThe Trigger settings along with timebase settings are the strengths for this sort of work.bdunham7 has given good tips to point you in the right direction however rather than focus on what you want to see/capture instead practice with a totally unrelated repetitive waveform to master how to set the scope and particularly use the more advanced triggers.A few screenshots follow of a signal bus (SCPI I think but that doesn't matter) that should give you a few tips to follow to help you on the way to getting the hang of using something other than a normal edge trigger.For the specific trigger for your use either Pulse or Interval with the appropriate edge should do what you want although it may need to be combined with a Single trigger.You can either capture long (slow timebase) then zoom in or use Zoom to see both slow and fast timebase waveforms in the dual window.Another tip for when you can't get rock solid stable triggering is to increase trigger Holdoff especially when dealing with the likes of a data packet so to prohibit the trigger to fire again until after the packet.Anyways, careful study of the below screenshots below should give you all the pointers you need and get you on the right track where you best to learn from experimentation rather than be handed the answer straight off.Come back with screenshots showing settings and menus if you have no luck and we'll give some more pointers.

author: sairfan1
author_rank: Frequent Contributor
timestamp: August 19, 2021, 07:02:53 pm
content: Sorry for later reply, i had to setup everything again and played a little bit before reverting back on answer.I was able to view the captured data what i was looking for, but still have some questionsQ 1:Please refer to picture 1, there is 0v in a red box what is this referring to?Q 2:In picture 1 we can see Channel 4 which was pulled up to 3.3v by 10K resistor, when uC sends 0 on it why it shows voltage level below zero on scale? sounds like -3.3vPlease Refer to Picture 2 Channel 1 (in Yellow) is pulled down by 10K resistor can be seen at zero even channel 1 also goes below zero, am i misunderstanding the concept here? or there is something with the setup?Q 3:Please refer to Picture 3, I zoomed in a captured pulse, I had to do lots of struggle by scrolling a lot to reach it, even its not visible in Picture 2, how can we view such unexpected things? like, every time do i have to scroll all way captured area?Q 4: how can i save parameters for later easy setting up the scopeThough i was able to capture what i wanted but still curious, is it possible to use an other trigger (or something like that) to stop capturing? just like i asked in my postFor example what if i want to start capturing when Channel 4 goes low but stop capturing when channel 1 goes up?

author: bdunham7
author_rank: Super Contributor
timestamp: August 19, 2021, 07:22:35 pm
content: 1) 0.00V refers to the position of the trace on the screen, which in this case means that a 0 volt signal should give you a line across the very center of the screen. This is indicated by the channel reference marker, which you have denoted with an arrow an the words 'ZERO VOLTS'.2) What you are showing indicates that the input signals are indeed below zero volts at those points. So the tip of the probe is 3-ish volts below the ground shell. However you have that setup is another story--if you think this is an error, we need details showing how you are connected.3) It's not easy and there are advanced triggering options to help, but it can be very difficult to spot these sorts of weird things if you don't have a good idea of roughly what you are looking for. Having a capture you can scroll through makes it about as easy as it is going to get if you have no advance knowledge of what might be there.4) There is a setting somewhere in the utility menu, I believe.Quote from: sairfan1 on August 19, 2021, 07:02:53 pmYou are misunderstanding the basic operation of the DSO. There can't be two triggers, the 'capture' is defined by the available memory length, the sample rate and one trigger point. The scope is actuallyalwayscapturing into a buffer. When a trigger event occurs, it designates 7 divisions worth of data, at whatever the current sampling rate is, as the 7 divisions displayed before the trigger point. It then captures another 7 divisions of data and then stops. The combination of the two is what you see on the screen. It can't go further because it will be out of memory (sort of--the details are more complex) and there would be little point in stopping sooner.

author: tautech
author_rank: Super Contributor
timestamp: August 19, 2021, 09:24:57 pm
content: sairfan1Some of your confusion seems to come from the levels you see which are directly related to the reference level, that is where you have the probe reference lead connected.For all scopes (other than isolated channel versions) the reference lead is at mains ground potential which introduces problems when/if connected to any part of a circuit that has a mains ground reference.When you have zero mains reference on a DUT you can safely connect the probe reference most anywhere however for sanity sake to understand what is displayed DUT circuit ground (0V) is the best place to connect.About your screenshots......all show the same trigger level which indicates you have not made any adjustments to its level.Stable triggering is very important to get proper results and if you see a horizontally moving waveform and the trigger level is not where it should be press the level encoder and the level will be set to 50% of the amplitude.Same with most other encoders...press and 0V/0s/50% is returned.For settings, the scope will remember last settings at reboot but if you have a preferred setup you wish to recall you can save one as your Default in the Save/Recall menu.Best advice is to use a factory Default first then make all the scope settings you wish to save and then select User Default from the menu. Factory Default can easily be returned from the Save/Recall menu.