Changing Ring Strings and Values in Strict TypeDefs Possible

[hfettig]

I was taught (and am teaching to my students) that in a Strict TypeDef the only things that are different from instance to instance are the Label, the Caption, the Description, and the TipStrip. Everything else is controlled by the typedef.

Now in LV 8.5.1 to some degree and in LV 8.6 to a higher degree I am able to change the strings of a strict typedef ring control from instance to instance:

In both LV 8.5.1 and 8.6 I can do the following:

• Create a Strict Typedef Ring Control (STRC)
  
• Drop a constant of that STRC onto a block diagram
  
• Right click the constant and select Edit Items
  
• You can now change the strings AND values if the items
  
• Close the dialog
  
• Right click on the STRC and select open typedef
  
• The typedef is unchanged but the constant has the new values
  
• If you change the constant to a control or indicator all the strings and values revert to the typedef settings
  

In LV 8.6 there is another related bug:

• Drop a control of that STRC onto a front panel
  
• Right click the constant and select Properties
  
• You get the full range of tabs displayed
  
• Representation shows up as EXT and is settable, although none of the settings are accepted
  
• Data Entry shows up with 0, 0, 0 limits which are settable, although none of the values are accepted
  
• Display Format shows up in advance editing mode
  
• Edit Items shows up with an empty list that is changable, although none of the new items are persistent
  
• Those tabs do not exist in LV 8.5.1 (and probably should not exist in 8.6 either)
  

Can anybody veryfy the constant bug earlier than 8.5?

[ned]

This is not a bug, it's a longstanding quirk in the way rings work. If you search through the Info-LabVIEW archives or NI Forums you'll find multiple explanations - try searching for strict typedef ring. In general your strict type definitions should always be enumerations, not rings.

EDIT: added this link from Info-LabVIEW which is the most thorough explanation I've seen.

http://sthmac.magnet.fsu.edu/infolabview/I...-10-26_015.html