Datatypes

Numeric types

A variety of numeric types exist with different sizes and properties complying with IEC61131.

Overview

When such a variable is declared without being initialized, it will be default-initialized with a value of 0 or 0.0 respectively.

A word on integer literals

Integer literals can be prefixed with either 2# (binary), 8# (octal) or 16# (hexadecimal). They will then be treated with regard to the respective number system.

Examples:

• i1 : DINT := 42; - declares and initializes a 32bit signed integer with value 42.
• i1 : DINT := 2#101010; - declares and initializes a 32bit signed integer with value 42.
• i1 : DINT := 8#52; - declares and initializes a 32bit signed integer with value 42.
• i1 : DINT := 16#2A; - declares and initializes a 32bit signed integer with value 42.

Strings

Overview

When such a variable is declared without being initialized, it will be default-initialized with a value of '' or "" respectively (empty strings).

STRING

RuSTy treats STRINGs as byte-arrays storing UTF-8 character bytes with a Null-terminator (0-byte) at the end. So a String of size n requres n+1 bytes to account for the Null-terminator. A STRING literal is surrounded by single-ticks '.

A String has a well defined length which can be defined similar to the array-syntax. A String-variable myVariable: STRING[20] declares a byte array of length 21, to store 20 utf8 character bytes. When declaring a STRING, the length-attribute is optional. The default length is 80.

Examples:

• s1 : STRING; - declares a String of length 80.
• s2 : STRING[20]; - declares a String of length 20.
• s3 : STRING := 'Hello World'; - declares and initializes a String of length 80, and initializes it with the utf8 characters and a null-terminator at the end.
• s4 : STRING[55] := 'Foo Baz'; - declares and initializes a String of length 55 and initializes it with the utf8 characters and a null-terminator at the end.

WSTRING (Wide Strings)

RuSTy treats WSTRINGs as byte-arrays storing UTF-16 character bytes with two Null-terminator bytes at the end. The bytes are stored in Little Endian encoding. A Wide-String of size n requres 2 * (n+1) bytes to account for the 2 byes per utf16 character and the Null-terminators. A WSTRING literal is surrounded by doubly-ticks ".

A WSTRING has a well defined length which can be defined similar to the array-syntax. A WSTRING-variable myVariable: WSTRING[20] declares a byte array of length 42, to store 20 utf16 character bytes. When declaring a WSTRING, the length-attribute is optional. The default length is 80.

Examples:

• ws1 : WSTRING; - declares a Wide-String of length 80.
• ws2 : WSTRING[20]; - declares a Wide-String of length 20.
• ws3 : WSTRING := "Hello World"; - declares and initializes a Wide-String of length 80, and initializes it with the utf16 characters and a utf16-null-terminator at the end.
• ws4 : WSTRING[55] := "Foo Baz"; - declares and initializes a Wide-String of length 55 and initializes it with the utf8 characters and a utf16-null-terminator at the end.

Date and Time

Overview

Note that RuSTy already treats TIME, TIME_OF_DAY, DATE and DATE_AND_TIME as 64 bit numbers. Therefore the long pendants LTIME, LTOD, LDATE and LDT are mere aliases to the original types.

DATE

The DATE datatype is used to represent a Date in the Gregorian Calendar. Such a value is stored as an i64 with a precision in nanoseconds and denotes the number of nanoseconds that have elapsed since January 1, 1970 UTC not counting leap seconds. DATE literals start with DATE# or D# followed by a date in the format of yyyy-mm-dd.

Examples:

• d1 : DATE := DATE#2021-05-02;
• d2 : DATE := DATE#1-12-24;
• d3 : DATE := D#2000-1-1;

DATE_AND_TIME

The DATE_AND_TIME datatype is used to represent a certain point in time in the Gregorian Calendar. Such a value is stored as an i64 with a precision in nanoseconds and denotes the number of nanoseconds that have elapsed since January 1, 1970 UTC not counting leap seconds. DATE_AND_TIME literals start with DATE_AND_TIME# or DT# followed by a date and time in the format of yyyy-mm-dd-hh:mm:ss.

Note that only the seconds-segment can have a fraction denoting the milliseconds.

Examples:

• d1 : DATE_AND_TIME := DATE_AND_TIME#2021-05-02-14:20:10.25;
• d2 : DATE_AND_TIME := DATE_AND_TIME#1-12-24-00:00:1;
• d3 : DATE_AND_TIME := DT#1999-12-31-23:59:59.999;

TIME_OF_DAY

The TIME_OF_DAY datatype is used to represent a specific moment in time in a day. Such a value is stored as an i64 value with a precision in nanoseconds and denotes the number of nanoseconds that have elapsed since January 1, 1970 UTC not counting leap seconds. Hence this value is stored as a DATE_AND_TIME with the day fixed to 1970-01-01. TIME_OF_DAY literals start with TIME_OF_DAY# or TOD# followed by a time in the format of hh:mm:ss.

Note that only the seconeds-segment can have a fraction denoting the milliseconds.

Examples:

• t1 : TIME_OF_DAY := TIME_OF_DAY#14:20:10.25;
• t2 : TIME_OF_DAY := TIME_OF_DY#0:00:1;
• t3 : TIME_OF_DAY := TOD#23:59:59.999;

TIME

The TIME datatype is used to represent a time-span. A TIME value is stored as an i64 value with a precision in nanoseconds. TIME literals start with TIME# or T# followed by the TIME segements.

Supported segements are:

• d ... f64 days
• h ... f64 hours
• m ... f64minutes
• s ... f64 seconds
• ms ... f64 milliseconds
• us ... f64 microseconds
• ns ... u32 nanaoseconds

Note that only the last segment of a TIME literal can have a fraction.

Examples:

• t1 : TIME := TIME#2d4h6m8s10ms;
• t2 : TIME := T#2d4.2h;
• t3 : TIME := T#-10s4ms16ns;

Other types

The BOOL type can either be assigned TRUE or FALSE. The type __VOID is the empty type and has an undefined size.

Bit datatypes are defined as follows: