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

Table 22 - Type conversion function features
a
A statement of conformance to feature 1 of this table shall include a list of the specific type
conversions supported, and a statement of the effects of performing each conversion.
b
Conversion from type REAL or LREAL to SINT, INT, DINT or LINT shall round according to
the convention of IEC 60559, according to which, if the two nearest integers are equally
near, the result shall be the nearest even integer, e.g.:
REAL_TO_INT(1.6) is equivalent to 2
REAL_TO_INT(-1.6) is equivalent to -2
REAL_TO_INT(1.5) is equivalent to 2
REAL_TO_INT(-1.5) is equivalent to -2
REAL_TO_INT(1.4) is equivalent to 1
REAL_TO_INT(-1.4) is equivalent to -1
REAL_TO_INT(2.5) is equivalent to 2
REAL_TO_INT(-2.5) is equivalent to –2
c
The function TRUNC shall be used for truncation toward zero of a REAL or LREAL, yielding
one of the integer types, for instance,
TRUNC(1.6) is equivalent to 1
TRUNC(-1.6) is equivalent to -1
TRUNC(1.4) is equivalent to 1
TRUNC(-1.4) is equivalent to -1
d
The conversion functions *_BCD_TO_** and **_TO_BCD_* shall perform conversions
between variables of type BYTE, WORD, DWORD, and LWORD and variables of type
USINT, UINT, UDINT and ULINT (represented by "*" and "**" respectively), when the
corresponding bit-string variables contain data encoded in BCD format. For example, the
value of USINT_TO_BCD_BYTE(25) would be 2#0010_0101, and the value of
WORD_BCD_TO_UINT (2#0011_0110_1001) would be 369.
e
When an input or output of a type conversion function is of type STRING or
WSTRING, the character string data shall conform to the external representation
of the corresponding data, as specified in 2.2, in the character set defined in
2.1.1.
2.5.1.5.2 Numerical functions
The standard graphical representation, function names, input and output variable types, and function
descriptions of functions of a single numeric variable shall be as defined in table 23. These functions
shall be overloaded on the defined generic types, and can be typed as defined in 2.5.1.4. For these
functions, the types of the input and output shall be the same.
The standard graphical representation, function names and symbols, and descriptions of arithmetic
functions of two or more variables shall be as shown in table 24. These functions shall be overloaded
on all numeric types, and can be typed as defined in 2.5.1.4.
The accuracy of numerical functions shall be expressed in terms of one or more implementation-