To add to this conversation a bit, here is what I've found:

This link explains how to use methods to capture user events. It builds a bit on the codesys store example for visualization events.
https://product-help.schneider-electric.com/Machine%20Expert/V1.1/en/core_visualization/index.htm?#t=topics%2F_visu_hook_user_input_events.htm%23CSH_195

While this explanation and the store example might be used to accomplish an automatic action with a user variable change.. it seems to have some very cumbersome requirements. For example, in order to discover which variable was changed by the event, the code has a long series of if statements which compare the pointer address of the changed variable to each and every pointer address you might be interested in. If it matches, then you could decide to do some action in that moment.

I suppose a function could be written to create a list of pointers that are of interest, and build a bit more functionality to it with a structured data type...

IF pbVarPointer <> 0 THEN
    IF pbVarPointer = ADR(PLC_PRG.xVar) THEN
    GetVariableName := 'PLC_PRG.xVar';
ELSIF pbVarPointer = ADR(PLC_PRG.xVar1) THEN
    GetVariableName := 'PLC_PRG.xVar1';
ELSIF pbVarPointer = ADR(PLC_PRG.xVar2) THEN
    GetVariableName := 'PLC_PRG.xVar2';
ELSIF pbVarPointer = ADR(PLC_PRG.iVar) THEN
    GetVariableName := 'PLC_PRG.iVar';
ELSIF pbVarPointer = ADR(PLC_PRG.iVar1) THEN
    GetVariableName := 'PLC_PRG.iVar1';
ELSIF pbVarPointer = ADR(PLC_PRG.iVar2) THEN
    GetVariableName := 'PLC_PRG.iVar2';
END_IF ///ETC... keep listing until you got them all

IF eTypeClass = __SYSTEM.TYPE_CLASS.TYPE_LINT AND dwVarSize = SIZEOF(LINT) THEN
    plInt := pbOldValue;
    sOut := CONCAT('LInt variable ', sVarName);
    sOut := CONCAT(sOut, ' changed from: ');
    sOut := CONCAT(sOut, LINT_TO_STRING(plInt^));
    plInt := pbNewValue;
    sOut := CONCAT(sOut, ' to: ');
    sOut := CONCAT(sOut, LINT_TO_STRING(plInt^));
    VisuElems.Visu_Output(sOut, VisuElems.LogClass.LOG_INFO);
END_IF

It then sets up a pointer to the value that changed (need one for each type of value that changes).

A question:
If i have a data structure with several elements, and the user changes one of the elements (perhaps an integer).. would this function return the pointer of the data structure or of the individual element that was changed?

Here is the normal 'write a variable' entry. The standard numberpad returns a string of "OK" with the close dialog action.

Is there any way to call a function with a pointer to the variable being changed with this close dialog option? I see no obvious reference to the variable...

Instead of write Variable, can use execute ST-Code which opens the dialog, and then continues on to do some other ST code after the dialog is closed?

I found a very cool possibility that uses custom implicit checks which seems as though they can be used to call functions based on things like variable changes and knowledge if the variable was read or written [Machine Control Studio].

One example project I found which was part of a customized codesys application set up to automatically call functions to read/write to variables to external components when used normally in code when they had special tags

{attribute 'get_access' := 'callafunctiontoReadData()'}
{attribute 'write_access' := fbToSendNetworkMessage()'}
myVariable: DINT;

Around their variable declarations. I did not fully understand the mechanism making this happen but found it to be awesomely useful. Variables without these attributes weren't affected by the code...

I thought using those tags around visualization variables could call an action similarly when written to as a possible solution.

I hope to start a bit of a discussion about this where:

if variable <> lastVariable then
    doSomething();
end_if
lastVariable := variable;

isn't sufficient for the situation.

How about using the OnDialogClosed feature from the Input Configuration. Viewable if you put the properties tab into expert/advanced mode. You can have structured text that toggles a variable then you can have logic somewhere that do something and reset that variable. Or have the ST do something else.

You could also just monitor that variable for any changes and then do something if it does change. In ladder logic I would use the EQ or NE function block possibly followed by R_Trig or F_Trig.

An example of that would be having a whole page with settings and then a DONE button. When you push the Done button it taps a variable that then write the name of a different visualization to the current visualization variable changing the screen to something else or allowing something to happen.

Edit: You definitely seem more capable than me so I'm not sure if what I said is helpful.

Morberis,

I think your suggestion to use OnDialogClosed makes a lot of sense, and I did a quick test and it does seem to work. The only real issue is that the dialog closes with the escape/cancel or ok. So this code would execute in either case i believe.

Maybe combining OnDialogClosed with a check of previous value to current value..