This operator is an extension of the IEC 61131-3 standard.
Instead of the INDEXOF operator, the ADR operator is provided in CODESYS V3 for obtaining a pointer at the index of a block. 
See also
This operator is an extension of the IEC 61131-3 standard.
Instead of the INDEXOF operator, the ADR operator is provided in CODESYS V3 for obtaining a pointer at the index of a block. 
See also