How do i change the item in the drop down list, and furthermore update the constant

[mexaviesta]

I have a drop down list Control that is full of items. I would like to change the lables on these items at runtime, as i knew, i should use the Ring but not Enum, because we can't change values of enum at runtime.

Furthermore i want to creat a Constant from this Control (drop down list ) on the block diagram, but if i edit the item list of the Ring control, LabVIEW does not automatically update the constant to which it is linked.

how can I solve it?

Thx and Best regards

Di

[GerdW]

Hi mexa,

- to automatically update constants on the BD when "their" control changes you need to make the control a typedef and create a typedef'd constant from it

- BUT: a ring constant will still not adapt to the changes of the control as that's not part of the typedef! To have it adapt you would need to use an Enum - which can't be changed at runtime…

Conclusion: you need to update the ring constant whenever you make changes to your BD…

[mexaviesta]

thanks a lot!!

[JensG69]

There is a trick to update "ring controls" from a type definition.

You have to:

- open the type def of the ring control.

- edit the items of the ring control.

- then you have to change the data type of the ring control (e.g. from U16 to U32).

- click on File -> Apply changes.

- undo the change of the data type of the ring control.

Done.

Crosspost to german LVF

[crossrulz]

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@jg69 wrote:

There is a trick to update "ring controls" from a type definition.

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Or just make it a Strict Type Def.  But then you can't programmatically update the items in the ring.  They will be set at design time.  This is pretty much required if you are going to have a constant anyways.