A structure (STRUCT) is a complex data type that can be nested in up to eight levels. The elements of a structure can be of any valid data type (except parameter types). The STRUCT data type must consist of at least two components, which must be located between STRUCT and END_STRUCT. A structure can be declared in the variable declaration table of a logic block or in a user-defined data type (UDT).

Using you can access the individual variables of a structure in the user program. A structure within another structure only counts as a component.