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LabVIEW
How can I programmatically remove a selection of plots from a waveform graph?
I have a waveform graph to display a number of plots, which I need to programmatically add and delete to as selections of data are chosen by the user for display.
I've looked under the VI Server Property node and cannot see anything suitable for adding extra plots, or removing existing plots. I expected to see a Plot Data array variable, with each element containing the data for each of the plots on the graph. There is such an array for the annotations, which I can easily edit by Removing Subset for Array, or Insert into Array, but nothing for the plot data. The Value property is a Variant, which I'm unsure how to handle. Should I be working with this perhaps? Can this be done by creating a Local Variable read node? Or am I missing something simple here??
I've looked under the VI Server Property node and cannot see anything suitable for adding extra plots, or removing existing plots. I expected to see a Plot Data array variable, with each element containing the data for each of the plots on the graph. There is such an array for the annotations, which I can easily edit by Removing Subset for Array, or Insert into Array, but nothing for the plot data. The Value property is a Variant, which I'm unsure how to handle. Should I be working with this perhaps? Can this be done by creating a Local Variable read node? Or am I missing something simple here??
Hi Mike,
I was trying to use the Property Node (Value) to read the waveform graph, but I was getting a Variant type back, not a 2D array of DBLs as I expected. Turns out I was passing the graph control reference to a subvi whose control refnum had the Include Type flag unchecked. As a result of this explicit definition, Value was of an uncertain (undefined) type and couldn't be natively provided. It would have had to have been cast into a more specific type to work. Have solved the problem by ensuring all my references are of a strict type, and now (as you recommend) the Property Node (Value) is useful
Many thanks for the response!
And many thanks for the demo too! You put that together remarkably quickly!
I was trying to use the Property Node (Value) to read the waveform graph, but I was getting a Variant type back, not a 2D array of DBLs as I expected. Turns out I was passing the graph control reference to a subvi whose control refnum had the Include Type flag unchecked. As a result of this explicit definition, Value was of an uncertain (undefined) type and couldn't be natively provided. It would have had to have been cast into a more specific type to work. Have solved the problem by ensuring all my references are of a strict type, and now (as you recommend) the Property Node (Value) is useful
Many thanks for the response!
And many thanks for the demo too! You put that together remarkably quickly!
