E0017: a VAR_EXTERNAL that matches no VAR_GLOBAL

VAR_EXTERNAL names a global variable declared in a VAR_GLOBAL block of the configuration, a resource, or a global variable list, with the same type (Ed.3 6.5.2.2). A global declared CONSTANT must be VAR_EXTERNAL CONSTANT where it is used (Ed.2 Table E.1).

VAR_GLOBAL counter : INT; END_VAR
PROGRAM p
VAR_EXTERNAL count : INT; END_VAR    (* E0017: no global named count *)
END_PROGRAM