Basic data types

Below are the available basic data types:

(*) Some of those data types may be not supported by all targets.

Structures

A structure is a complex data type defined as a set of members. Members of a structure may have various data types. A member of a structure may have dimensions or may be an instance of another structure.

When a structure is defined, it may be used as other data types to declare variables.

Members of a structure may have an initial value. In that case, corresponding members of all declared variable having this structure type will be initialized with the initial value of the member.

For specifying a member of a structured variable in languages, use the following notation:

    VariableName.MemberName

Enumerated data types

You can define some new data types that are enumaration of named values. For example:

type: LIGHT

values: GREEN, ORANGE, RED

Then in programs, you can use one of the enumerated values, prefixed by the type name:

Light1 := LIGHT#RED;

Variables having enumerated data types can only be used for assignment, comparison, and SEL/MUX functions.

UNIONs

A kind of user defined Data types. As structures, a UNION is defined as a set of data members, each member having a name and a data type.

But unlike for structures, all members of a UNION are implemented at the same location in the memory and thus overlap.

In languages, access to a member of a UNION is done the same way as for structures, using the “.” separator: variable_name.member_name

Hint: The option Store complex variables in a separate segment must be enabled.

Restrictions:

A UNION cannot:

• contain STRING members
• have an initial value
• work with the Soft Scope

"Bit fields" data types

You can define new data types derived from integer data types, that have some readable names for some of their bits. Thus you can use VarName.BitName notations in programs. Such data types cannot be derived from the LINT type.

Arbitrary grouping of bits into evaluable integer values

You can configurate bits groups inside a bit field for the bit field types:

• BYTE
• WORD
• DWORD
• LWORD

The bit fields are shown in the Spylist view too.

When typing the same „symbol“ in consecutive lines of the value field, the binary values (sum of the single bits) is displayed on that symbol in the IEC program.

This, essentially, works starting from only 1 single bit to the maximum number of bits of integer values. In this way, the source value can be grouped accordingly into several groups of 1 to n-bits.

Hint: Extended bit filds (more than one bit) are not supported for 64bit datatypes.

Example: An 16 bit integer value is split up into:

• Single Bit (bit 0), with name “AlarmActive”
• Group of 4 Bits (bit 1 to 4), with name “AlarmCode” representing value 0 to 15
• Group of 3 Bits (bit 5 to 7), with name “AlarmLocationID” representing value 0 to 7

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