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ps2000_set_trigger

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ps2000_set_trigger

Postby KennyM » Wed Sep 30, 2009 8:20 pm

I have a query about the ps2000_set_trigger SDK Method.

The SDK document describes the 'delay' parameter thus :

delay, the delay, as a percentage of the requested number of
data points, between the trigger event and the start of the block. It should be in the range -100% to +100%. Thus, 0% means that the trigger event is at the first data value in the block, and -50% means that it is in the middle of the block. If you wish to specify the delay as a floating-point value, use ps2000_set_trigger2()
instead.


This does not make sense! If the range is -100 to +100, then -50 would be one-quarter of the way into the block, not half way, and 0% would be the middle not the start!

Can we have some calrification on the actual value to be entered here please!

For reference I looked at what PicoScope 6 does - and the range it lets you specify is 0% to +100%.[/b][/quote]
-Kenny M.
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Postby Erik » Thu Oct 01, 2009 8:11 am

Hi Kenny,

The delay is the time from the trigger point until the capture starts.

If the delay is positive the trigger point will have past when the capture starts and will not be seen in the data.

If the delay is negative the trigger point will be inside the capture.

If the delay is 0% the whole capture will be just after the trigger point.
i.e. the trigger point is at the beginning of the data.

If the delay is -100% the trigger point is at the very end of the captured data.

If the delay is -50% the trigger point is centered in the captured data.

The time of your capture can be calculated according to [capture_time = capture_rate * capture_count].
Your trigger delay in time is the [delay_time = delay_percent * capture_time].
Last edited by Erik on Thu Oct 01, 2009 8:31 am, edited 1 time in total.
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Postby KennyM » Thu Oct 01, 2009 8:19 am

Thanks for the clarification.
It makes sense now :-)
-Kenny M.
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Postby KennyM » Thu Oct 01, 2009 8:57 am

Thanks - I understand that now :-)

I had been thrown of course a little because PicoScope 6 only allows values between 0 and 100% .

Thanks again.
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