Hi,
I did not try it with the Beckhoff driver, but I guess it will stay the same within the Drivers.
So may you Can try "DrvConfig.Options.SymbVarName" as your dynamic property path. This was used in zenon 7.60. In zenon 7.11, you may do not Need the "Options" part.
Btw, you Can check the dynamic properties name with the function "getDynamicPropertyEnum", which returns a string[] with all dynamic properties for a certain zenon item.
Manual -> Programming
Interfaces -> Objectmodel -> Driver -> Driver-Methods ->
DynPropertiesEnum[GET]
BR
Christian