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LabVIEW programming topics - elements in arrays

Using arrays (1)

The following vi demonstrates how to intialize and change the elements of a 20x20 array.

The following steps describe how to create this vi.

  • Open a new vi.
  • Go to the block diagram and add a sequence structure.
  • Use frame 0 (at this stage actually without number) to initialize the array. Here an array with 20 rows and 20 columns is filled with 1's.
    • Put a 'Initialize Array' node inside the frame. Pop up on the 'Initialize Array' node and select 'Create'/'Indicator'. This will create an array indicator on the front panel, which can be renamed to 'initialized array'. Reposition the terminal of this indicator outside the sequence structure.
    • Pop up on the terminal and select 'Create'/'Local Variable'. Position the local variable node inside frame 0. Next connect the output of the 'Initialize Array' node to the local variable node.
    • Connect the desired constant values to the 'Initalize Array' node. Pop up on it's connectors and select 'Create'/'Constant' to create the right numerical constants.

    • Add a frame after this frame.
  • Use frame 1 to fill the array with random values.
    • Add two nested 'For Loops' that both will count to 20.
    • Add a 'Replace Array Subset' node.
    • Add a 'Random number (0-1)' node.
    • Add a 'Multiplication' node.
    • Add two local variables for 'initialized array'. Use one to read from - pop up on one of the local variables node and select 'Change to read'- by wiring it to the 'Replace Array Subset' input. Use one to write to by wiring it to the 'Replace Array Subset' output.


    • Add a frame after this frame.
  • Use frame 2 to put the array data in an intensity graph.
    • From the 'Controls' palette put a intensity graph on the front panel.
    • In the diagram place the terminal of the intensity graph inside frame 2.
    • Add a local variable for 'initialized array', enable reading from it, and connect it to the intensity graph terminal.

The vi as described in the text.

See also...

- How to do basic array calculations.
- How to use arrays in 'for loops'.

Bart Boshuizen, 2005/02/02

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