Attention

IronPLC supports IEC 61131-3 Structured Text excluding I/O mapping.

VariablesΒΆ

Variables in IEC 61131-3 are declared in blocks within program organization units. This section covers the declaration syntax, qualifiers, and scoping rules.

Topic

Description

Variable Declarations

Variable declaration blocks

I/O Qualifiers

Direct addressing (%I, %Q, %M)

Variable Scope

Variable scope keywords

Retention

Retention and constant qualifiers

Initial Values

Variable initialization