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ThresholdDirection Above/Rising issues

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ThresholdDirection Above/Rising issues

Postby Sigge83 » Mon Mar 14, 2016 10:10 am

Hi
I'm currently writing my own application, and I'm noticing that I encounter the same problem when I use the PicoScope 6 software. Which is when I want to use the "Trigger type", i.e. ThresholdDirection, Above instead of Rising the oscilloscope won't trigger. I'm measuring a DC signal with a little ripple, and I would wan't the Oscilloscope to trigger if the DC signal is above say 1 Volt but it won't trigger. It works fine though if I use the Above trigger type and place the threshold at the middle of the ripple (6,5 volts). But then it's exactly as using the rising edge trigger type. Have I misunderstood how to use the different trigger types?

above1.png


above6.png
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Re: ThresholdDirection Above/Rising issues

Postby Martyn » Mon Mar 14, 2016 1:38 pm

In the PicoScope pictures you have a logic trigger, this is intended for when you want to look at a triggering on something happening on two or more channels at a the same time. If you use this trigger with only one channel active, it is the same as a simple rising edge trigger, so it is correct that it only triggers when the threshold is within the signal range.

The little pictures in the trigger window for the other trigger types should enable you to select the correct trigger for your purpose.
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Re: ThresholdDirection Above/Rising issues

Postby Sigge83 » Tue Mar 15, 2016 8:20 am

Ok, but what I want is for the oscilloscope to trigger on a signal that is above a certain value, how do I do it?

Because based on what you wrote the Logic trigger would work if channel A & B was measuring the same signal and both had the "above 1 volt" condition, but as you see in the image below, I get the same results.

aboveab.png
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Re: ThresholdDirection Above/Rising issues

Postby Martyn » Tue Mar 15, 2016 9:14 am

I have just tested here and with both A and B set to above, and using an AND logic trigger it appears to be functioning correctly for me.

Can you post the details from Help->About so that I can then check that I am using the same setup as you, additionally if you post the psdata file, File->Save, I can run with your exact settings.
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Re: ThresholdDirection Above/Rising issues

Postby Sigge83 » Tue Mar 15, 2016 10:10 am

Hi
I had not even considered the logic AND/OR statments. And the strange thing with them is that the seem to be working in the opposite way than what they should. Because if I change one of the signals (it does not matter which of them) to trigger above 6.5 volts the oscilloscope triggers even though I use the AND logic. But if I, on the other hand, use the OR logic, I must set the level to 6.5 on both signals to get a trigger!
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20160315-0002.pssettings
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picoabout.png
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Re: ThresholdDirection Above/Rising issues

Postby Sigge83 » Tue Mar 15, 2016 10:13 am

By the way did you also measure on a DC signal? Because I get the same result as you do if measure on a sine wave (or any signal that doesn't have a DC offset i.e. it has a zero crossing). And then the logical operators AND/OR also behaves the way the should.

Kind Regards
Sixten
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Re: ThresholdDirection Above/Rising issues

Postby Martyn » Wed Mar 16, 2016 8:50 am

My signal had started below the threshold. I will perform some additional tests and then discuss this with the development team.
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Re: ThresholdDirection Above/Rising issues

Postby Sigge83 » Tue Mar 22, 2016 8:08 am

Hello Martyn,
I do not want to seem impatient, but have you had a chance to discuss it with your development team?

Best Regards
Sixten
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Re: ThresholdDirection Above/Rising issues

Postby Martyn » Tue Mar 22, 2016 10:59 am

Had an interesting discussion with the development team, the behaviour was as defined, however they agreed that it was incorrect. We now have an updated driver which will allow this to work correctly in your application, PicoScope 6 will not currently support this, and will require a future upgrade.

Please email support@picotech.com and I will supply the driver and details on how to implement the additional functionality, released documentation will take a while to catch up.
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