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Calling Functions and Function Blocks
16.3.2
Input Assignment (FC)
Basic Principle
Input assignments assign values (actual parameters) to the formal input
parameters of the called FC. The FC can work with these actual parameters
but cannot change them. In contrast to an FB call, this assignment is not
optional with an FC call. Input assignments have the follwing syntax:
Input Assignment
Actual parameters
Expression
TIMER
IDENTIFIER
:=
IDENTIFIER
Parameter name of the
input parameter
(formal parameter)
Figure 16-12
Actual Parameters
in Input
Assignments
COUNTER
IDENTIFIER
BLOCK
IDENTIFIER
Syntax of an Input Assignment
The following actual parameters can be assigned in input assignments:
Table 16-4
Actual Parameters in Input Assignments
Explanation
Actual Parameter
Expression
An expression represents a value and consists of addresses
and operators. The following types of expression are
possible:
Mathematical, logical or comparative expressions
Constants
Extended variables
Special
Consideration
16-16
TIMER/COUNTER
Identifier
Defines a specific timer or counter to be used when a block is
processed (see also Chapter 17).
BLOCK
Identifier
Defines a specific block to be used as an input parameter. The
block type (FB, FC or DB) is specified in the declaration of
the input parameter. When assigning parameters, you specify
the block address. You can use either the absolute or the
symbolic address (see also Chapter 9).
Note that FB in/out parameters and FC parameters are not permissible as
actual parameters for formal FC input parameters of a non-elementary data
type.
Structured Control Language (SCL) for S7-300/S7-400, Programming
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