Variable: RETAIN

Retain variables are declared by the keyword ‎RETAIN‎ is added in programming objects in the scope ‎VAR‎, ‎VAR_INPUT‎, ‎VAR_OUTPUT‎, ‎VAR_IN_OUT‎, ‎VAR_STAT‎, or ‎VAR_GLOBAL‎.

Syntax for the declaration

<scope> RETAIN
    <identifier>: <data type> ( := <initialization> )? // ( ... )? : Optional
END_VAR
<scope> : VAR | VAR_INPUT | VAR_OUTPUT | VAR_IN_OUT | VAR_STAT | VAR_GLOBAL

An assignment of inputs, outputs, or memory addresses with the ‎AT‎ keyword is not permitted.

Example

In a POU

VAR RETAIN
        iVarRetain: INT;
END_VAR

In a GVL

VAR_GLOBAL RETAIN
        g_iVarRetain: INT;
END_VAR