Applies To:
  • CitectSCADA 7.0
Summary:
I am trying to use TagInfoEx with nType parameter 0 or 18 in CitectSCADA 7.0 to determine if a particular Variable Tag exists. However, it does not return an empty string if the Variable Tag does not exist, as TagInfo did in previous versions of CitectSCADA. Why is this and what can I do to resolve this? 

Solution:
Unfortunately, the behaviour of the TagInfoEx Cicode function is slightly different to the TagInfo function. Modes 0 and 18 will simply return the value that is passed into the sName parameter so it can be used with other Cicode functions, even if the specified Variable Tag does not exist. It is recommended to use a different nType parameter value such as 10 to determine if a particular Variable Tag Exists.

The Help in CitectSCADA 7.10 has been updated to ensure that the end user is not misled into thinking that it will return an empty string if the specified Variable Tag does not exist.

 
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