Write and Read from Arrays (.lvm) in LabVIEW

[mareva]

Description

Description-Separate-1

Overview

This VI exemplifies how to write and read from a .lvm file.

Description

This VI allows the user to write and read from a .lvm file. It is possible to use a custom file name and the code verifies if the generated path is valid or not. This could be useful to easily write and read a file that could stop measurement data with additional information that describes it.

You could find more information about the .lvm file format in the following document:
Specification for the LabVIEW Measurement File (.lvm)

Requirements
LabVIEW Base Development System.

Steps to Implement or Execute Code
1. Open the attached VI " Write - Read lvm Files LV 2012 - NI verified.vi".
2. Run the VI.
3. Select a valid file name.
    3.1 In case the file name is incorrect to select a valid one.
4. Click the “Save button” to save the File.
5. You can also process the read it data by pressing the “Process Data” button.

Additional Information or References

 

**This document has been updated to meet the current required format for the NI Code Exchange.**

Description-Separate-2

[altenbach]

This code is 10 times (!) more complicated that it needs to be and contains many mistakes.

• Overuse of local variables
• Sequences that can be replaced by proper dataflow.
• Greedy loops.
• No main loop.
• latch action booleans outside their event structure (they don't reset when clicked).
• Incorrect representations. Why convert to I32 when everything is coerced back to DBL a nanosecond later?
• Indexing with the iteration terminal instead of autoindexing.
• "Index array" can be resized for multiple outputs
• No diagram comments
• complicated loop implementations of existing LabVIEW primitives (Array min/max, writee to spreadsheet file).
• You don't need a formula express VI to see if an integer is odd or even, besides, you should never used this with DBL.

Here is a quick comparison of parts of your code with suggested alternatives.

(see also this discussion) My suggestions are just rough drafts. You might need to tweak a little bit for correct functionality.

(1) To zero all odd elements, you could do one of the following alternatives instead of your code monster (top):

(how many times do you possibly need to read from a different local variable of the same array! They all contain the same data! Don't be afraid to branch a wire)

(2) To get the minimum of each row of a 2D array and write it to a file, you could do it your way (above) or the easy way (below):