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How Can I Acquire Pretrigger Samples with NI-SCOPE?

Primary Software:
Primary Software Version: 3.0
Primary Software Fixed Version: N/A
Secondary Software: N/A

I am using the NI-SCOPE driver and I would like to acquire pretrigger samples, how can this be done?

With NI-SCOPE, you can specify how many pretrigger samples you want to acquire using the reference position input of the niScope Configure Horizontal in LabVIEW, or the refPosition argument of the niScope_ConfigureHorizontalTiming function in a text-based programming language.

The reference position (refPosition) input specifies the position of the Reference Event in the waveform record as a percentage of the record. This percentage can range from 0-100%, and will represent the number of pretrigger versus posttrigger points that are stored.

For example, a 0% reference position means that all of the points stored in the record will have arrived immediately after the trigger, while the 100% reference position means that the record will consist entirely of points that occurred immediately prior to the trigger. Similarly, a 50% reference position means that half of the record will be pretrigger samples and half will be posttrigger samples.

ni_Scope Configure Horizontal Timing VI, reference position highlighted
NI-SCOPE Configure Horizontal Timing with a reference position of 50%

Related Links:
NI High-Speed Digitizers Help: Horizontal:Reference Position Property
NI High-Speed Digitizers Help: Coercions of Horizontal Parameters


Report Date: 03/27/2007
Last Updated: 06/08/2012
Document ID: 47QC624G

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