signals vs waveforms

[michael.bielmann@gmx.ch]

Is there anywhere some information which relates to the advantages and disadvantages of using Signals or Waveforms? Are they essentially the same? Waveforms seem not appropriate for non-uniform X/Y-Data (variable aquisition rate). Does the same hold true for Signals? What is the most multipurpose way to represent non-uniform X/Y-Data? It all seems quite confusing and there seems no place where this is really elaborated.

Thanks in advance for you help to a newbie!

[parthabe]

Does this have anything related to LabVIEW?

Else, please do a Google search.

[michael.bielmann@gmx.ch]

I think it does: It's about the fundamental difference between Array based Signals, Waveforms and Signals like used in Express-VI's. Google was my first try, but to no avail.

[parthabe]

I think Waveforms will have Timestamp included in them by default, but Signals wont be having them generally.

Please correct me, if I m wrong.

[GerdW]

Hi,

you're talking about "dynamic datatype" (DDT) of ExpressVis? Those DDT are (more or less) an array of waveforms, so they have a timestamp included.

I prefer to work with simple arrays to keep xy-data...

[F._Schubert]

As far as my experience goes (I prefere the raw data of arrays, as most data in my apps are of xy-type), ddt is related to Express VIs.
So when prototyping with Express VIs, the DDT is really nice in terms of programming speed. But once the coding starts, using 'traditional'/'real' VIs all these conversions from/to DDT start polluting the Diagram. A DDT might be of different data types (similar to variant data), and polymorphic VIs (and controls) adapt to these. From that comes the advantage during prototyping, as you still can easily change the actual data type.
Waveforms as said before contain timing information. They are ok if you're only interested in a signal vs. time data (evenly spaced time!). But when I wanted to do more than just wire them to a graph, things quickly messed up. Such things as Waveform subset never worked the way I expected them to work (mainly a thing with the timestamp and absolute vs. relative), so they wasted more time than donated for the coding.
One thing thats performed better with Waveforms than arrays is to display ditigtal data, as the nice digital graph won't work with boolean arrays.
Arrays are the most clear, strict data type of all these. That's why I would do all real coding with these only.

Short:
* DDT for prototyping
* Waveform if signal vs. time is all
* Arrays for everything

Holds true for LV 7.1, don't know about the newer versions.
And also, I guess some fresh trained programmers will outperform me with DDT or waveforms where they are useful.

Felix

[michael.bielmann@gmx.ch]

Tanks for your excellent replies! See much clearer now! Special Thanks to Felix - very clear answer.

Michael