It looks that the "Formula Data Reference" is not working when we use attribute of type "string". At least, the PI AF System Explorer is displaying an error message.
I have created a single-element with 2 attributes model to demonstrate :
attribute1 is a static attribute of type string, the contents of which is a simpe string "MyString"
attribute2 is a Forumal Data Reference that should simply refer to the value of attribute1.
PI AF System Explorer displays a strange error message : "Data was not available for attribute 'Attribute1': myString"
It Looks like the system is accessing properly the value but with a status stating that there is an error !
Any explanation from AF experimented users ? Thanks in advance....