Displaying absolute Time of a waveform channel

[yledieu]

Hello,

I would like to display absolute timestamps on the x-axis of a 2D graph in the VIEW window from waveform channels in a TDMS File. The timestamp of the first sample is stored in the wf_start_time property.

I have found this article but i don't want to generate a time channel because the benefit of waveforms is to avoid storing the x part of the signal in the files.

Is there another solution since 2007 ?

I'm using DIAdem 2011 and LV 2011.

Thanks in advance

[Brad_Turpin · Accepted solution]

Hi Yohann,

The only way to display datetime values on the X axis of graphs in VIEW, and the only standard way to do so for graphs in REPORT, is to create a DateTime channel.  In DIAdem 2011 this is much easier to do, since you can use the standard ANALYSIS function "Generate Numeric Channel", selecting the radio buttons "Values from x-part of a waveform channel" and "Create time channel (absolute time reference)".  You can also use the standard ANALYSIS function "Numeric Channels <==> Waveform Channels".

Brad Turpin

DIAdem Product Support Engineer

National Instruments

[yledieu]

Thank you for your help Brad,

So, can you tell me what is the effect of the "wf_time_pref" property in a TDMS waveform channel ?

Don't you think it could be a good idea to post in the Diadem Idea Exchange forum to have Diadem automatically displaying datetime values of a waveform when wf_time_pref is "Absolute" ?

[Brad_Turpin]

Hi Yohann,

 The "wf_time"pref" property has the expected effect in LabVIEW, but currently DIAdem ignores this property completely.  I agree that DIAdem should add functionality to easily display the absolute date/time component of waveform channels.  Please feel free to add this request at the DIAdem Idea Exchange if it's not already there.  This is already on my personal short list of requests for DIAdem R&D.

Brad Turpin

DIAdem Product Support Engineer

National Instruments