There are facilities in diagnostics to observe unresolved references. However, it is recommended that you establish and verify dynamic references in SFC pulse/assignment type actions. If a dynamic reference is used, you should make sure that it is bound (that is, a value is assigned) before continuing the step. This can be done using pulse action confirmation or a transition condition.
To establish and verify dynamic references, the SFC expression could be written as follows:
The action expression resolves the dynamic reference path and assigns it to the .$REF field of the dynamic reference parameter at the module level or phase level.
The confirmation expression tests that the value of the .CST field is equal to 0 (connected) and the .$REF field is not blank: ('PARAMETER.$REF' <> "") AND ('PARAMETER.CST' = 0) .
Subsequent expressions should test the .CST field of the individual dynamic reference parameters to guide the SFC execution if the algorithm is going to handle missing or IGNORE connections.