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

Table 27 - Standard selection functions
d
No.
Graphical form
Explanation/example
1
+-----+
| SEL |
BOOL--|G |--ANY
ANY---|IN0 |
ANY---|IN1 |
+-----+
Binary selection
c
:
OUT := IN0 if G = 0
OUT := IN1 if G = 1
EXAMPLE:
A := SEL(G:=0,IN0:=X,IN1:=5) ;
2a
+-----+
| MAX |
ANY_ELEMENTARY--| |--ANY_ELEMENTARY
: ---| |
ANY_ELEMENTARY--| |
+-----+
Extensible maximum function:
OUT := MAX (IN1,IN2, ...,INn)
EXAMPLE:
A := MAX(B,C,D) ;
2b
+-----+
| MIN |
ANY_ELEMENTARY--| |--ANY_ELEMENTARY
: ---| |
ANY_ELEMENTARY--| |
+-----+
Extensible minimum function:
OUT := MIN (IN1,IN2, ...,INn)
EXAMPLE:
A := MIN(B,C,D) ;
3
+-------+
| LIMIT |
ANY_ELEMENTARY--|MN |--ANY_ELEMENTARY
ANY_ELEMENTARY--|IN |
ANY_ELEMENTARY--|MX |
+-------+
Limiter:
OUT := MIN(MAX(IN,MN),MX)
EXAMPLE:
A := LIMIT(IN:=B,MN:=0,MX:=5);
4
e
+-----+
| MUX |
ANY_INT--|K |----ANY
ANY------| |
: ------| |
ANY------| |
+-----+
Extensible multiplexer 
a, b, c
:
Select one of N inputs
depending on input K
EXAMPLE:
A := MUX(0, B, C, D);
would have the same effect as
A := B ;
NOTE 1
The notations IN1, IN2, ..., INn refer to the inputs in top-to-bottom order; OUT refers
to the output.
NOTE 2
Usage examples and descriptions are given in the ST language defined in 3.3.
a 
The unnamed inputs in the MUX function shall have the default names IN0, IN1,...,INn-1 in
top-to-bottom order, where n is the total number of these inputs. These names may, but need not,
be shown in the graphical representation.
b 
The MUX function can be typed as defined in 2.5.1.4 in the form MUX_*_**, where * is the type
of the K input and ** is the type of the other inputs and the output.
c 
It is allowed, but not required, that the manufacturer support selection among variables of derived
data types,
as defined in 2.3.3, in order to claim compliance with this feature.
d
It is an error if the inputs and the outputs to one of these functions are not all of the same actual
data type, with the exception of the G input of the SEL function and the K input of the MUX function.
e
It is an error if the actual value of the K input of the MUX function is not within the range {0..n-1}.
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– 62 –
61131-3 
 IEC:2003(E)