Iec 61131-3 Second edition 2003-01 Programmable controllers – Part 3: Programming languages

Figure 7 - Examples of explicit type conversion with overloaded functions
Type declaration
(ST language - see 3.3)
Usage
(FBD language - see 4.3)
(ST language - see 3.3)
VAR
A : INT ;
B : INT ;
C : INT ;
END_VAR
+---------+
A---| ADD_INT |---C
B---| |
+---------+
C := ADD_INT(A,B);
NOTE Type conversion is not required in the example shown above.
VAR
A : INT ;
B : REAL ;
C : REAL;
END_VAR
+-----------+ +----------+
A---|INT_TO_REAL|---| ADD_REAL |---C
+-----------+ | |
B-------------------| |
+----------+
C := ADD_REAL(INT_TO_REAL(A),B);
VAR
A : INT ;
B : INT ;
C : REAL;
END_VAR
+---------+ +-----------+
A---| ADD_INT |---|INT_TO_REAL|---C
| | +-----------+
B---| |
+---------+
C := INT_TO_REAL(ADD_INT(A,B));
Figure 8 - Examples of explicit type conversion with typed functions
IEC 2477/02
IEC 2478/02
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61131-3 
 IEC:2003(E)
– 55 –
2.5.1.5 Standard functions
Definitions of functions common to all programmable controller programming languages are given in
this subclause. Where graphical representations of standard functions are shown in this subclause,
equivalent textual declarations may be written as specified in 2.5.1.3.
A standard function specified in this subclause to be extensible is allowed to have two or more inputs
to which the indicated operation is to be applied, for example, extensible addition shall give as its
output the sum of all its inputs. The maximum number of inputs of an extensible function is an