# Timestamp problem DAQmx waveform

I have a program that reads analog signals multiple DAQmx using a PFI trigger from a DIO card to start the acquisition.   It uses a registry to offset and Boolean logic to stop the DAQmx read the loop when the trigger is low.  I traced the result to a curve of waveform.  I have a 1000 S/s scanning speed.  I traced the data to a graph of waveform and eye on the individual data points and it is perfect.  Exactly 1 S/s.  The problem: when I increase my 5000 S/s scan rate... I see exactly 1 S/s, but the displayed duration of my test data is 5 x more time.  That tells me that my graph of the waveform is plotted in fact each data point individual 1ms apart.  So basically, there a 1ms all dt in the waveform, and it does not change.  How can I get the real dt of the analysis of data here instead of this arbitrary constant?  When I look at a text of my waveform data file, I see the timestamp below where I'm expecting something ending like that...  0,0010, 0,0017, 0.0025, etc..  Any help would be appreciated.  I'll post the VI if necessary, but other than the trigger power, is a fairly straightforward HERE DAQms read.  Thank you in advance.

The time of LV start date is January 1, 1904 midnight GMT.  Since your shows up to 6 hours before that, he must be GMT - 6.  My horodateurs base are 19:00 31/12/1903, which is GMT - 5.  Eastern time zone.

Are you any error coming out after your Subvi waveforms?

You empty an array of waveform data to add.  The default waveform has a T0 zero and a detachment of the 1.  In the Sub - VI of waveform append inside your Subvi if dt' it does not raise an error, (in fact a caveat being the 1802 error code is positive.).  But she proceeds to add data and use the dt and T0 the first waveform which is initially as the default data in the initial iteration.  I think that if you start with an array of wavefrom that has the number of channels of the need, an empty array of Y, but a correct dt.  Then the dt should be correct.  That, or you can put in your Subvi a case structure where the first call, or if the incoming waveform is empty, it is not add and uses only the 2nd waveform.

You have also a little a Rube Goldberg enters your Subvi.  It could be simplified as shown in the picture as an attachment.

Tags: NI Software

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I am pleased that you have something that can work even if it is not ideal.
I close this service request, but I thought that I'll let you know that
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http://digital.NI.com/public.nsf/allkb/5D42CCB17A70A06686256DBA007C5EEA?OpenDocument

Concerning

Vince Methot
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