WagoAppCanLayer2 is not providing all the CAN messages received by the 750-658 CANBUS gateway

CODESYS
1

Hello,
I am trying to receive a NMEA2000 fast-packet message, meaning that the entire message is sendt in multiple frames right after each other. In WAGO -IO-CHECK-3 I have verified that all the frames in the message are received by the 750-658 can-bus gateway. However, when I try to process the messages in CODEYS 3.5.19 by using the state-machine in the code below I sometimes seam to get the same message twice. I use the wCounter in the FbCanRx29BitFrame to check if there are any new messages, based on this I trigger the _xRXTrigger to receive a new message which I then process. However, when I process the message, I often get the same data in the message twice, regardless that the wCounter has increased (which I assume is the truth).

First off, is it ok to use the wCounter as and indicator that there is a new message to receive? Is it just that I am handling this wrong, or are there any known issues about processing messages from the CANbus gateway in CODESYS?

Any tips to help me be able to process all the messages received by the CANBUS-gateway in CODESYS, will be appreciated!


//This must be runned every cycle, regardless of the processing afterwards
FbCanL2Open(
	xEnable:= TRUE, 
	I_Port:= _750_658_24, 
	udiBaudrate:= 250000, 
	dwFlags:= 2#00000000_00000000_00000000_01010011, 
	dwPara:= , 
	xValid=> , 
	xBusy=> , 
	xError=> , 
	oStatus=> );
	
currentTime := TIME(); // Get current time

CASE state OF 
	
	INIT:
		//initialisation state
		state := COMMUNICATING;
	RESET:
		// Reset the communication, in case of hold-ups when communicating or as a fall-back in an error state
	
	COMMUNICATING: 
		IF FbCanL2Open.xValid AND NOT FbCanL2Open.xError THEN
			state:= LISTENING;
		ELSE
			STATE:= ERROR;
		END_IF	
		
	
	LISTENING:
		// call the WAGO CANBUS FB to get the updated wCounter;
		
			_FbCanRx29BitFrame(
				xEnable		:= _xEnable, 
				I_Port		:= _750_658_24, 
				xBufferMode	:= _xBufferMode, 
				dwCanId		:= _wCanId, 
				xBufferMode	:= _xBufferMode, 
				xRxTrigger	:= _xRxTrigger, 
				xValid		=> _xValid, 
				xError		=> _xError, 
				xBusy		=> _xBusy, 
				oStatus		=> oStatus, 
				wCounter		=> _wCounter, 
				wFrames		=> _wFrames, 
				//xRtrFrame	=> _xRtrFrame, 
				bRxNBytes	=> _bRxNBytes, 
				aRxBuffer	=> _aRxBuffer);
		
		IF 	_wCounter > fetchedMsgCnt  THEN
			IF _xBufferMode THEN
				lastwCount:= lastwCount +1; //count one by one upwards
			ELSE
				lastwCount := 	_wCounter; //Skipping whichever msg we missed
			END_IF
			
			state:= FETCHING_MSG;
			_xRxTrigger:= TRUE; //Set the trigger to true to avoide the need to handle this in fetching			
		END_IF
		
	FETCHING_MSG:		
		_FbCanRx29BitFrame(
				xEnable		:= _xEnable, 
				I_Port		:= _750_658_24, 
				xBufferMode	:= _xBufferMode, 
				dwCanId		:= _wCanId, 
				xBufferMode	:= _xBufferMode, 
				xRxTrigger	:= _xRxTrigger, 
				xValid		=> _xValid, 
				xError		=> _xError, 
				xBusy		=> _xBusy, 
				oStatus		=> oStatus, 
				wCounter		=> _wCounter, 
				wFrames		=> _wFrames, 
				//xRtrFrame	=> _xRtrFrame, 
				bRxNBytes	=> _bRxNBytes, 
				aRxBuffer	=> _aRxBuffer);
			
			IF NOT _xRxTrigger AND NOT _xBusy AND NOT _xError AND _xValid THEN
					
				fetchedMsgCnt:= fetchedMsgCnt+1;
				frame := _aRxBuffer;
				

				(* Shift existing frames down *)
				FOR i := 100 TO 1 BY -1 DO
					arrayOfFrames[i] := arrayOfFrames[i - 1];
				END_FOR
				
				(* Insert new frame at the top *)
				arrayOfFrames[0] := frame;

				state := PROCESSING_MSG;
				
			END_IF

		
	PROCESSING_MSG:
		firstByte := frame[0];
		sequenceNumber := SHR(firstByte,5) ;
		frameCounter := TO_UINT(firstByte AND 16#07);
		
		loc := TO_UINT(frame[5] AND 16#0F); 
		
		IF frameCounter = 0  THEN
			firstFrameProcessing:= firstFrameProcessing +1;
			lastSequenceNumber:= sequenceNumber;
			IF loc = 1 THEN
				nBowMsgs := nBowMsgs+ 1 ;
			END_IF
			
			IF loc = 2 THEN
				nSternMsgs:= nSternMsgs +1;
			END_IF		
		
		END_IF
		processedMsgCnt:=processedMsgCnt+1;
		
		IF _wFrames>0 THEN
			IF max_nBufferedMsgs <_wFrames THEN
				max_nBufferedMsgs := _wFrames;
			END_IF
		END_IF
			
		state := COMMUNICATING;
		
	
	DROPPING_MSG:
		droppedMsgCnt:= droppedMsgCnt+1;
		state:= COMMUNICATING;
		
	ERROR:
		IF previousState <> state THEN
            errorCount := errorCount + 1;
            errorStart := currentTime;
		END_IF			
			errorTimer:= currentTime - errorStart;
		state := COMMUNICATING;
END_CASE

previousState := state;