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pulse width triggering

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pulse width triggering

Postby jswanson » Thu Mar 07, 2013 10:04 am

I have a 2205MSO running 6.6.50.3

I cant get the pulse width trigger to work. The signal is about 12khz square wave @ 5V.

Pulse direction = Pos or Neg
condition = Greater than
Threshold 2V
Hysteresis = 0
I can't get the scope to trigger id the time is greater than 0s. ( At 0s it triggers all the time.)

I'm sure this used to work!

Jeremy.
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Re: pulse width triggering

Postby ziko » Thu Mar 07, 2013 3:05 pm

HI Jeremy it should work perfectly fine, could you send me your psdata file?
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Re: pulse width triggering

Postby jswanson » Thu Mar 07, 2013 3:49 pm

001 shows the waveform (DMX512)
002 is triggering from CH A pulse width > 80us. (anythig > 0s and it doesn't trigger)
Attachments
20130307-0002.psdata
Triggering off CHA
(10.28 KiB) Downloaded 100 times
20130307-0001.psdata
Triggering off CHB
(17.78 KiB) Downloaded 100 times
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Re: pulse width triggering

Postby ziko » Thu Mar 07, 2013 5:01 pm

Hi,

You have the probe on x10, the actual trigger will be on the raw value rather than the scaled value. Reduce your trigger value to be say 200mV.

Hope this helps.
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Re: pulse width triggering

Postby ziko » Thu Mar 07, 2013 5:24 pm

Correction! The scaling now also works with the triggering! So that might not be your problem! I know older versions of PicoScope did not scale the trigger values. Are the settings you created from an older version of the software or did you create them from scratch?
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Re: pulse width triggering

Postby jswanson » Thu Mar 07, 2013 5:42 pm

The settings are created from scratch. The trigger point looks to be in the correct place. If I adjust the time to 0 seconds the waveform triggers, but anything larger than that (like 300ns) then it doesn't.
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Re: pulse width triggering

Postby Martyn » Fri Mar 08, 2013 7:19 am

You should be using a window dropout trigger with threshold 1 set to 4.0V, threshold 2 set to -2.0V, and the time set to 80us

as shown in the top left picture when selecting that trigger type.
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Re: pulse width triggering

Postby jswanson » Fri Mar 08, 2013 9:20 am

Nope. Still doesn't work. Look at this:http://i.imgur.com/MqOkkjt.gif
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Re: pulse width triggering

Postby jswanson » Fri Mar 08, 2013 9:28 am

This is the waveform triggering from CHB, so it should trigger: http://i.imgur.com/3bD8EBa.png. Is there a reason why this wouldn't work with pulse width triggering?
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Re: pulse width triggering

Postby ziko » Fri Mar 08, 2013 10:11 am

Hi,

The pulse width should work, we both tried it so your problem is a bit of a strange one! What I would say is try reset the start up settings and then load the start up settings and then reconfigure your settings. Let me know how you get on.
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Re: pulse width triggering

Postby ziko » Fri Mar 08, 2013 10:29 am

What I would also say is try removing the probe settings and just have your raw readings. Also could you get the driver version from help-> about.
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Re: pulse width triggering

Postby jswanson » Fri Mar 08, 2013 10:32 am

I tried resetting the startup settings and restarting the application but I am still having the same problem.

I can't get it to trigger on any value >0. http://i.imgur.com/wo6CC1v.gif
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Re: pulse width triggering

Postby ziko » Fri Mar 08, 2013 11:08 am

AHAAAAAAAAAA! I figured out the problem! I was using a 2205, not a 2205MSO! I can recreate your problem on 6.50.3, however the latest beta version and the latest standard version seem to work. So 6.6.57.18 and beta 6.7.15. 6.6.57 can be found on the normal download whilst the beta can be found in the following link:

http://labs.picotech.com/#psw6

Let me know how you get on.
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Re: pulse width triggering

Postby jswanson » Fri Mar 08, 2013 11:17 am

Hi,

The beta works fine now thanks.

Jeremy.
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