Best way to pass an array of waveforms inbetween VIs

In my VI I am developing I have multiple data sources that output a single waveform. I group these waveforms togeather to make a wave form array. The user selects which waveform they would like to display and they are displayed on a graph on a different form. Right now I have each different graph VI generating the whole array and displaying the selected element.
My question is, this seems to be not efficent because I am generating data in 3 spots. I would think it would be better to generate it in one spot and then pass only the need data to the three graph VIs. What is the best way todo this? A global variable? Queue? Any suggestions?

You're probably tired of hearing me say this, but the global function idea is the best.
A global variable makes a COPY of the data each time you read it. That takes time, and memory. If each of 3 window reads the global, and picks out a channel, then you've made 3 copies of the original data. Depending on your data size, that may or may not be a problem.
A queue means that once you read the data, it's lost from the queue. If window A reads from the queue, that data chunk is not in the queue any longer, so Window B can't read that same data.
If the main window generates the data and deposits it in a global function, then each window can ask the global function for a specific channel to display.
DATA STORAGE.vi:
Inputs:
WRITE/read (bool
ean)
DATA IN (2-D array of DBL, for example)
Channel Index (I32)
Outputs:
DATA OUT: 1-D array of DBL (or waveform, maybe).
Code:
WHILE
If WRITE/read
Store DATA IN in a shift reg.
else
Pass Shift reg IN to Shift reg Out.
Pick out channel via CHANNEL INDEX
Pass selected data to DATA OUT.
Loop NEVER.
The purpose of the loop is just to have a shift reg. It doesn't really loop - it executes once per call.
Steve Bird
Culverson Software - Elegant software that is a pleasure to use.
Culverson.com
Blog for (mostly LabVIEW) programmers: Tips And Tricks

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Message Edited by Christian L on 01-31-2007 12:00 PM
Christian Loew, CLA
Principal Systems Engineer, National Instruments
Please tip your answer providers with kudos.
Any attached Code is provided As Is. It has not been tested or validated as a product, for use in a deployed application or system,
or for use in hazardous environments. You assume all risks for use of the Code and use of the Code is subject
to the Sample Code License Terms which can be found at: http://ni.com/samplecodelicense
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Best way to pass an array of waveforms inbetween VIs

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