TwinCat3 how to efficiently setup the EventLogger in an OOP?

I'm still very new to OOP and TwinCat so please bear with me. I'm currently developing the software for a small machine that will be used combined with the TF2000 HMI. Because the Event Grid takes away a lot of work I want to set up the TC3 EventLogger. I understand how you create alarms etc. and I can display them in the HMI Event Grid.

It works great with single events, but now I want to take it further and add the errors of every function block. For example FB_TemperatureController can report overheat, FB_Motor can report a stop error and so on.

How do I setup the event logger so I can send the same error from every instantiated FB?

I thought of creating a FB_FaultHandler:

FUNCTION_BLOCK FB_FaultHandler
VAR
    fbEventLogger       : FB_TcEventLogger;
    aMessages           : ARRAY [0..100] OF Fb_TcMessage;
    aAlarms             : ARRAY [0..100] OF Fb_TcAlarm;
END_VAR

METHOD init
VAR_INPUT
END_VAR

aAlarms[0].CreateEx(Tc_Events.AlarmEvents.Error_Overtemp, TRUE, 0);
aAlarms[1].CreateEx(Error2, TRUE, 0);
aAlarms[2].CreateEx(Error3, TRUE, 0);
aAlarms[3].CreateEx(Error4, TRUE, 0);
aAlarms[4].CreateEx(, TRUE, 0);
aAlarms[5].CreateEx(, TRUE, 0);
aAlarms[6].CreateEx(, TRUE, 0);

There's a few things I don't like about this tho:

The source of the event would always be FB_FaultHandler but I want it to display the concerning FB
I'm not sure how to raise an alarm from different instances twice. For example: fbTemp1 and fbTemp 2 are both instances of FB_TemperatureController. Now if I create a "SetFault" Method in the FB_FaultHandler, which raises and confirms an alarm it would raise the same error twice without me knowing the source.

METHOD setError
VAR_INPUT
  nErrorId: INT;
  bErrorActive: BOOL;
END_VAR

I'd prefer if the array would be set up with the id of an event. So "Error_Overtemp" has id 96 and the FB_FaultHandler will put it in aAlarms[96]

I haven't really found any real samples about this anywhere. I watched the Webinar but it honestly is described very poorly. I'd be thankful for any help, input or examples of a good event logger.

Solution

Off the top of my head with some help of the internet. Don't have a system for compiling at hand. But you could do something like this code below.

Essential there is a baseclass for logging (your FB_FaultHandler). From this all classes with logging functionality can be derived from. It uses reflection for the instance path. I never used reflection in twincat as I usually solve this kind of problem a little different. But it is the most generic solution I guess.
An example for the final class is FB_MyClassesWithLoggingFunctionality.

There is also a small stub for the initialization code in MAIN. You have to initialize and trigger the setting of Info Class FB_SourceInfo. It sets the instance information in the FB_SourceInfo. That is a class that you can handover to the CreateEx Method and should provide the source of the instance information.

In the below example of MAIN the source info would be like -project-.MAIN.fbClass

// -------------- Base class for all classes with logging
{attribute 'reflection'}
FUNCTION_BLOCK FB_FaultHandler
VAR
    {attribute 'instance-path'}
    {attribute 'noinit'}
    sErrorSource : STRING; // make sure that this variable is large enough to hold the path

    fbFaultInfo : FB_SourceInfo;

    fbEventLogger       : FB_TcEventLogger;
    aMessages           : ARRAY [0..100] OF Fb_TcMessage;
    aAlarms             : ARRAY [0..100] OF Fb_TcAlarm;
END_VAR


METHOD InitInfo
fbFaultInfo.InitInfo(sErrorSource);
// example: use faultInfo
aAlarms[0].CreateEx(Tc_Events.AlarmEvents.Error_Overtemp, TRUE, fbFaultInfo);
END_METHOD

METHOD logError
VAR_INPUT
    errorId : INT;
END_VAR
END_METHOD
   // Raise error
END_FUNCTION_BLOCK


// ------------ FB for source Info
FUNCTION_BLOCK FB_SourceInfo IMPLEMENTS I_TcSourceInfo 
VAR
    sSourceInfo : STRING
METHOD InitInfo
VAR_INPUT
    source : STRING
END_VAR
sSourceInfo := source;

END_METHOD


END_FUNCTION_BLOCK

// ------------------  Final class that has logging functions
FUNCTION_BLOCK FB_MyClassesWithLoggingFunctionality EXTENDS FB_FaultHandler

METHOD DoSomething
VAR_INPUT

END_VAR

IF bError then
    logError(id);
END_IF
END_METHOD


// Usage
PROGRAM MAIN
VAR
    fbClass : FB_MyClassesWithLoggingFunctionality;
    bInit : BOOL;
END_VAR
IF NOT bInit THEN
    fbClass.InitInfo();
    bInit := FALSE;
END_IF

END_PROGRAM