Error when calling Top Row property of a listbox passed as reference

[Nokaroa]

I have a listbox that I want to scroll down when data is added to it, so users can always see the bottom of the queue. In the VI with the listbox, I set the Top Row property to (NumRows -  # rows) and it works fine. But I moved this to a subVI and passed a reference to the listbox control. The subVI uses a LstBox (strict) control, but when I call the Top Row property node for the reference, it throws up Error 1077: Invalid property value. 

Attached is a snippet of the VI. Labview 2020

[billko]

I think it is because the reference is a strictly typed one.  Certain properties are not allowed to be changed when the reference is strictly typed.

[UliB]

Is your property node 'Height' a 'Size:Height' property node? If yes you subtract a value in pixels from 'Number of Rows' which results very likely in a negative value, an invalid property value for 'TopRow'.

Instead of Height you need the number of 'ItemNames' in your calculation.

[Emna20]

Hi,

you could use this solution :

Best Regards.

Thank you (kudos )

[Nokaroa]

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@Emna20 wrote:

Hi,

you could use this solution :

Best Regards.

Thank you (kudos )

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I don't see any difference between your solution and my code.

[UliB · Accepted solution]

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@Nokaroa wrote:

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@Emna20 wrote:

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I don't see any difference between your solution and my code.

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Obviously there is a difference. You use 'Height' in your calculations, Emna20 uses the size of the array.

But be careful. If NumRows is greater than the size of the array, the difference can be negative, which is not a valid input for TopRow.

You have to limit the value for TopRow to be greater or equal to 0. Look at the attached VI.

[Nokaroa]

I understand. This solved it. Thank you everyone