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

implementation-dependent parameter
. The actual number of inputs effective in a formal call of an
extensible function is determined by the formal input name with the highest position in the sequence of
parameter names.
EXAMPLE 1
The statement
X := ADD(Y1,Y2,Y3);
is equivalent to
X := ADD(IN1 := Y1, IN2 := Y2, IN3 := Y3);
EXAMPLE 2
The following statements are equivalent:
I := MUX_INT(K:=3,IN0 := 1, IN2 := 2, IN4 := 3);
I := 0;
2.5.1.5.1 Type conversion functions
As shown in table 22, type conversion functions shall have the form *_TO_**, where “*” is the type of
the input variable IN, and “**” the type of the output variable OUT, for example, INT_TO_REAL. The
effects of type conversions on accuracy, and the types of errors that may arise during execution of
type conversion operations, are implementation-dependent parameters.
Table 22 - Type conversion function features
No.
Graphical form
Usage example
1
a,b,e
+---------+
* ---| *_TO_** |--- **
+---------+
(*) - Input data type, e.g., INT
(**) - Output data type, e.g., REAL
(*_TO_**) - Function name, e.g., INT_TO_REAL
A := INT_TO_REAL(B) ;
2
c
+-------+
ANY_REAL---| TRUNC |---ANY_INT
+-------+
A := TRUNC(B) ;
3
d
+-------------+
*--| *_BCD_TO_** |---**
+-------------+
A := WORD_BCD_TO_INT(B);
4
d
+-------------+
**--| **_TO_BCD_* |---*
+-------------+
A := INT_TO_BCD_WORD(B);
NOTE Usage examples are given in the ST language defined in 3.3.
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61131-3 
 IEC:2003(E)