This is a short tutorial on relative tag path referencing for multiple levels. The Ignition help has a page labeled Tag Paths but it only shows relative referencing for the current folder, or all the way back to the tag provider at its root. Maybe this will help those who want to reference tags that are one or more levels above the current level.
For this tutorial, I have built three levels, named Parent, Child, and Grandchild. In the Parent folder is a simple string type memory tag named ParentTag. Its text is ‘This is the ParentTag text’. In the Child folder is another simple string type memory tag named ChildTag whose text is ‘This is the ChildTag text’. Here is a snip from the browser showing that much.
In the Grandchild folder are two simple string type expression tags named ChildTagText and ParentTagText. These two tags will reference the memory tags in the folders above them using relative tag path expressions. The expression for ChildTagText, which references ChildTag, a level up from it, is shown below.
Notice that the expression is within curly braces and begins with [.] which is a reference to the current folder. Next is … which means move up a level. And finally is a / and the tag name in the Child folder.
The expression for ParentTagText, which references ParentTag, two levels up is shown below.
Again, within the curly braces we start with [.] to reference the current folder, then …/… which means move up two levels, then a / and the tag name in the Parent folder. To show the results, below is a snip from the fully expanded area in the SQL tags browser. Notice that the text in ChildTagText is the same as the text in ChildTag, and the text in ParentTagText is the same as the text in ParentTag.
I hope this helps.