We can start a project from scratch or we can start from any existing sample (to save time)

=> We pick an existing sample (because this will be extended for other purposes)

=> Let’s download the sample from https://www.hemelix.com/plc/state-machine-in-structured-text/  (Down the sample project (HistoricalData_Hemelix.zip))

=> If we notice there is no event-related implementation there, we are going to add there.

=> Download EventLogger Nuget package

Now switch to the PLC program

=> Right Click on Type System | Add New Item | YardGateEvents

=> Double-click on YardGateEvents

=> Right click on the empty space | New |  rename the NewEventClass as YardGateAlarm

=> Rename Event as ObstacleDetected and add another one ContactorFault according to our specification

=> ObstacleDetected_DisplayText is the key which is an identifier of a localizable text, Our two alarms have added

Now let’s add the messages

=> We have 5 messages according to our specifications (DoorCloseTime, DoorOpenTime, YardGateStarting, YardGateDoorOpened, YardGateClosed)

=> Press on the empty space | New | Name it as YardGateMessage | Add the above Events

=> DoorCloseTime_DisplayText can be formatted as Door close time = {0}, we shall display closing time so we need {}

=> We add the following code to FN_MAINYARDGATE function block

    tDelta, tStart, tEnd : TIME;  //For counting time, closing/opening time
    contactorAlarm : BOOL := FALSE; //We shall have a button in HMI for setting true or false just to simulate it
    fbLogger        :FB_TcEventlogger;
    fbAlarm         :FB_TcAlarm;
    fbSource        :FB_TcSourceInfo;
    fbArgument      :FB_TcArguments;

=> We add a new state YARD_ALARM

TYPE YARDGATESTATE :
(
    YARD_UNINIT := 0,
    YARD_INIT,
    YARD_CLOSED,
    YARD_OPENING,
    YARD_OPENED ,
    YARD_CLOSING,
    YARD_BLOCKED,
    YARD_ALARM //New
);
END_TYPE

When the contactorAlarm is TRUE the gate goes to YARD_ALARM  state. We raise the alarm and clear the alarm in the following way.

YARD_ALARM :
IF NOT stateInit THEN
stateInit:= TRUE;
fbSource.Clear();
fbSource.sName := 'Contactor fault';
fbAlarm.CreateEx(TC_Events.YardGateAlarm.ContactorFault, TRUE, fbSource);
fbAlarm.Raise(0);
END_IF	
IF NOT contactorAlarm  THEN		
	state :=YARD_UNINIT;
	tStart := TIME();
	stateInit:= FALSE;	
	fbAlarm.Clear(0, TRUE);
END_IF	

We need to display the time taken when opening or closing the yard. It can take varying amount of time (for example there were obstacle in front of yard). We shall record the time and display it in the event logger in the following way.

DoorCloseTime_DisplayText    Door close time = {0}  // See the YardGateMessage, DoorCloseTime and translation

fbArgument.Clear();
fbArgument.AddString('Yard Gate Closed');
fbLogger.SendMessageEx(TC_Events.YardGateMessage.YardGateStarting,fbSource,0,fbArgument);	
tEnd := TIME();
tDelta := tEnd - tStart;			
fbArgument.Clear();		
fbArgument.AddInt(TIME_TO_INT(tDelta));
fbLogger.SendMessageEx(TC_Events.YardGateMessage.DoorCloseTime,fbSource,0,fbArgument);	

For more see the YouTube Video, the same example has been explained step by step.