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| GW Instek MDO-2302A delayed trigger bug? |
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| evgus:
Hi everyone! I encountered a problem using delayed trigger in GW-Instek MDO-2302A. Sometimes it works as intended, but sometimes wrong. For example, if I want to trigger on the second pulse in a packet, I use delayed trigger mode with event count set to 1 and it works fine. But then I change event count to 2, and it triggers randomly on the first, second or third pulse. If I set event count to 3 it works correctly again, and so on. The same problem in ‘Delay time length’ mode. At some ‘delay times’ it works correctly, at some – just triggers on the first edge with no delay at all. Here is video demonstration: https://youtu.be/JL_RYlNBuN0 Have someone encountered issues like that? Is it a problem of exact device, or is it a firmware bug (latest firmware installed)? May be I’m doing something wrong? Any ideas? Thanks Eugene |
| tautech:
Welcome to the forum. For simple trigger timeout on datastreams a simple mistake is to use a timeout not quite long enough and a longer packet comes along and mucks it all up. :rant: The remedy of course is dead simple; increase the trigger timeout. |
| 2N3055:
--- Quote from: evgus on March 08, 2021, 07:42:59 am ---Hi everyone! I encountered a problem using delayed trigger in GW-Instek MDO-2302A. Sometimes it works as intended, but sometimes wrong. For example, if I want to trigger on the second pulse in a packet, I use delayed trigger mode with event count set to 1 and it works fine. But then I change event count to 2, and it triggers randomly on the first, second or third pulse. If I set event count to 3 it works correctly again, and so on. The same problem in ‘Delay time length’ mode. At some ‘delay times’ it works correctly, at some – just triggers on the first edge with no delay at all. Here is video demonstration: https://youtu.be/JL_RYlNBuN0 Have someone encountered issues like that? Is it a problem of exact device, or is it a firmware bug (latest firmware installed)? May be I’m doing something wrong? Any ideas? Thanks Eugene --- End quote --- Are you in Auto or Normal trigger mode? >:D You need to change to Normal trigger mode. EDIT: I apologize, I saw the video and you did change to Normal mode. Disregard my question. You shouldn't have such a large holdoff value. Try setting holdoff to time just bigger than pulse burst , say 12-15 usec. With pulse trigger you use you shouldn't need holdoff at all. Also you use rising pulse as trigger start, you should use falling edge, so it's not triggering on first falling pulse and count from there but from somewhere else. I don't have that scope, but it seems to me that this particular trigger works a bit different than you''re trying to use it. |
| evgus:
--- Quote from: tautech on March 08, 2021, 07:48:21 am ---Welcome to the forum. --- End quote --- Thanks! --- Quote from: tautech on March 08, 2021, 07:48:21 am ---For simple trigger timeout on datastreams a simple mistake is to use a timeout not quite long enough and a longer packet comes along and mucks it all up. :rant: The remedy of course is dead simple; increase the trigger timeout. --- End quote --- I mean "trigger timeout" is the same as "Holdoff time", am I correct? The problem shows up even on short test packet of just 8 pulses. Even if holdoff time is much longer than packet duration. |
| tautech:
--- Quote from: evgus on March 08, 2021, 08:48:03 pm --- --- Quote from: tautech on March 08, 2021, 07:48:21 am ---For simple trigger timeout on datastreams a simple mistake is to use a timeout not quite long enough and a longer packet comes along and mucks it all up. :rant: The remedy of course is dead simple; increase the trigger timeout. --- End quote --- I mean "trigger timeout" is the same as "Holdoff time", am I correct? --- End quote --- Yes. Try a falling edge trigger which is more normal for simple decoding. |
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