Attribute 'init_on_onlchange'

The pragma causes the variable, to which the pragma is applied, to be initialized with each online change.

	Fast online change For small changes (e.g. in the implementation section, with no shifting of variables required), a "fast online change" is performed. In this case, only the modified function block is compiled and reloaded. In particular, no initialization code is generated in this case. This also means that no code for initializing variables with the attribute 'init_on_onlchange' is generated. This usually has no effect, as the attribute is usually used to initialize variables with addresses. However, a fast online change does not result in variable address changes. To ensure the init_on_onlchange attribute is applied to the entire application code, disable fast online change for the PLC project using the no_fast_online_change compiler definition. To this end, insert the definition in the Compile category of the PLC project properties.

	The attribute 'init_on_onlchange' has no effect for individual FB variables The Attribute 'init_on_onlchange' only applies to global variables, program variables and local static variables of function blocks. To reinitialize a function block during an online change, the function block instance must be declared with the attribute. The attribute is not evaluated for a single variable in a function block.

Syntax: {attribute 'init_on_onlchange'}

Insert location: Line above the declaration line of a variable

Sample

VAR_GLOBAL
    {attribute 'init_on_onlchange'}
    bFastOnlineChange : BOOL := FALSE;
END_VAR

{attribute 'call_after_online_change_slot' := '4567'}
FUNCTION OnlineChangeDetection : BOOL
VAR_INPUT
END_VAR
VAR
END_VAR

IF GVL_OnlineChangeDetection.bFastOnlineChange THEN
    // here you know that you are inside a FastOnlineChange
END_IF
// reset for next detection
GVL_OnlineChangeDetection.bFastOnlineChange := TRUE;