PLC Programming

Constants
(see also Appendix C: Datentypen, Time Data Types)
DATE_AND_TIME Constants
Date constants and the time of day can also be combined to form so-called DATE_AND_TIME
constants. DATE_AND_TIME constants begin with "dt#", "DT#", "DATE_AND_TIME#" or
"date_and_time#". Place a hyphen after the date followed by the time.
Examples:
DATE_AND_TIME#1996-05-06-15:36:30
dt#1972-03-29-00:00:00
(see also Appendix C: Datentypen, Time Data Types)
Number Constants
Number values can appear as binary numbers, octal numbers, decimal numbers and hexadecimal
numbers. If an integer value is not a decimal number, you must write its base followed by the number
sign (#) in front of the integer constant. The values for the numbers 10-15 in hexadecimal numbers will
be represented as always by the letters A-F.
You may include the underscore character within the number.
Examples:
14 (decimal number)
2#1001_0011 (dual number)
8#67 (octal number)
16#A (hexadecimal number)
These number values can be from the variable types BYTE, WORD, DWORD, SINT, USINT, INT,
UINT, DINT, UDINT, REAL or LREAL.
Implicit conversions from "larger" to "smaller" variable types are not permitted. This means that a
DINT variable cannot simply be used as an INT variable. You must use the type conversion.
REAL/LREAL Constants
REAL and LREAL constants can be given as decimal fractions and represented exponentially. Use
the standard American format with the decimal point to do this.
Example:
7.4 instead of 7,4
1.64e+009 instead of 1,64e+009
STRING Constants
A string is a sequence of characters. STRING constants are preceded and followed by single
quotation marks. You may also enter blank spaces and special characters (umlauts for instance).
They will be treated just like all other characters.
In character sequences, the combination of the dollar sign ($) followed by two hexadecimal numbers
is interpreted as a hexadecimal representation of the eight bit character code. In addition, the
combination of two characters that begin with the dollar sign are interpreted as shown below when
they appear in a character sequence:
$$ Dollar signs
$'
$L or $l Line feed
$N or $n New line
Single quotation mark
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