Literals

A literal is a constant value written directly in the source. logiccloud supports the IEC 61131-3 literal forms described below.

Numeric literals

Integers

Decimal integers may use _ as a digit separator for readability.

1000
1_000_000

A literal can be typed by prefixing it with a type name and #:

INT#42
SINT#-5
UDINT#1_000

Number bases

Bit-string and integer literals can be written in other bases with a base prefix and #. Digits may be grouped with _.

Prefix	Base	Example
`16#`	Hexadecimal	`16#FF`, `16#DEAD_BEEF`
`8#`	Octal	`8#777`
`2#`	Binary	`2#1010_0001`

mask  := 16#00FF;
flags := 2#1010_1010;

Real literals

Real literals contain a decimal point and may carry an exponent. They can be typed with REAL# / LREAL#.

3.14159
1.0E-9
-2.5E3
LREAL#6.022E23

Boolean literals

TRUE
FALSE
BOOL#TRUE

0 and 1 are also accepted as boolean values where a BOOL is expected.

Character and string literals

Single-byte strings (STRING) are written in single quotes; double-byte strings (WSTRING) in double quotes. Single characters use the CHAR# / WCHAR# prefix.

'Hello, world'      // STRING
"Grüße"             // WSTRING
CHAR#'A'            // single CHAR
WCHAR#"Ω"           // single WCHAR

Escape sequences

The dollar sign $ introduces an escape inside a string or character literal:

Escape	Meaning
`$$`	A literal dollar sign `$`
`$'`	Single quote (in single-byte strings)
`$"`	Double quote (in double-byte strings)
`$L` / `$l`	Line feed
`$N` / `$n`	Newline
`$P` / `$p`	Form feed (page)
`$R` / `$r`	Carriage return
`$T` / `$t`	Tab
`$<hh>`	Single-byte character by hex code (two hex digits)
`$<hhhh>`	Double-byte character by hex code (four hex digits, `WSTRING`)

line := 'Name:$TValue';      // tab between Name: and Value
quote := 'It$'s ready';      // embedded single quote
nul := '$00';                // a NUL character by hex code

Time and duration literals

A duration literal starts with T# (or TIME#) and combines day/hour/minute/ second/millisecond/microsecond/nanosecond components. LTIME# (or LT#) denotes a long duration.

Unit	Suffix
Days	`d`
Hours	`h`
Minutes	`m`
Seconds	`s`
Milliseconds	`ms`
Microseconds	`us`
Nanoseconds	`ns`

T#500ms
T#1h30m
T#2d4h30m15s
LTIME#10s500ms
T#-100ms          // durations may be negative

Components must appear in descending order of magnitude and a fractional value is allowed on a component (e.g. T#1.5h).

Date and time-of-day literals

Kind	Prefix(es)	Example
Date	`D#`, `DATE#`	`D#2026-06-08`
Long date	`LD#`, `LDATE#`	`LD#2026-06-08`
Time of day	`TOD#`, `TIME_OF_DAY#`	`TOD#14:30:00`, `TOD#14:30:00.250`
Long time of day	`LTOD#`, `LTIME_OF_DAY#`	`LTOD#23:59:59.999`
Date and time	`DT#`, `DATE_AND_TIME#`	`DT#2026-06-08-14:30:00`
Long date and time	`LDT#`, `LDATE_AND_TIME#`	`LDT#2026-06-08-14:30:00.500`

start  := DT#2026-06-08-08:00:00;
midday := TOD#12:00:00;
today  := D#2026-06-08;