Technical data

Appendix
27.3 Data Types and Parameter Types
Programming with STEP 7
624 Manual, 05/2010, A5E02789666-01
27.3.4.8 Permitted Data Types when Transferring Parameters
Rules for Transferring Parameters Between Blocks
When you assign actual parameters to formal parameters, you can specify either an absolute
address, a symbolic name, or a constant. STEP 7 restricts the valid assignments for the various
parameters. Output and in/out parameters, for example, cannot be assigned a constant value
(since the purpose of an output or an in/out parameter is to change its value). These restrictions
apply particularly to parameters with complex data types to which neither an absolute address nor
a constant can be assigned.
The following tables illustrate the restrictions (--) involving the data types of actual parameters that
are assigned to formal parameters.
The valid assignments are shown by the z symbol.
Elementary Data Types
Declaration
Type
Absolute
Address
Symbolic Name
(in the Symbol Table)
Temporary Local
Symbol
Constant
Input
z z z z
Output
z z z
--
In/out
z z z
--
Complex Data Types
Declaration
Type
Absolute
Address
Symbolic Name of the DB
Element
(in the Symbol Table)
Temporary Local
Symbol
Constant
Input --
z z
--
Output --
z z
--
In/out --
z z
--