Logic Trigger

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d_davis
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Logic Trigger

Post by d_davis » Thu Mar 05, 2009 9:02 am

Hello,
I'm using a 2205 with V6.2.2.2. I've tried to use the advanced logic trigger on some simple signals but I'm experiencing lots of problems. Even triggering with Above/Below thresholds on a single trace seems to not work correctly. In particular, if I trigger a simple logic level pulse train (Trigger = Below 2.6V) the resulting trigger is the rising edge (at T=0) and not the falling edge as I would expect. Even if I change to Above 2.6V the trigger point remains the same. Is this a known issue or am I doing something completely wrong?

Robin
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Post by Robin » Thu Mar 05, 2009 9:45 am

Hi

I have just checked this and it appears to be working correctly.

Can you post your settings file, so I can see exactly which settings you have?

('file | save current waveform as' and save as a .pssettings file)

Robin

d_davis
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Post by d_davis » Thu Mar 05, 2009 10:05 am

Hi,

Attachment as requested.

Regards,
Darren
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logic_trigger.zip
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Robin
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Post by Robin » Thu Mar 05, 2009 10:14 am

Hi Darren

This appears to be OK. What conditions are you trying to trigger on?

Robin

d_davis
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Post by d_davis » Thu Mar 05, 2009 10:27 am

CH_A set to Not Used. Triggering on CH_B as [Level below 2.6V]. With this configuration I would expect the trigger point to be the falling edge of the pulse i.e. as it transitions from above 2.6V to below 2.6V. However, it triggers on the rising edge instead. If I change the trigger to [Above 2.6V] it triggers on the rising edge as expected. If I change the trigger to [Falling below 2.6V] then it triggers correctly. When I introduce CH_A in the logic I get even more unexpected results. It's as though the trigger point is when the requested condition is no longer met?

Regards,
Darren

Robin
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Post by Robin » Thu Mar 05, 2009 3:16 pm

You're right, there does appear to be a problem with the 'falling' option in logic triggering. We will look in to this further.

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