https://content.helpme-codesys.com/en/CODESYS%20CANbus/_can_f_j1939_diagnosis_application.html you need this : VAR J1939_ECU:j1939.J1939RemoteECUDiag; DM1_ :j1939.DM1_Read; DTCliste : J1939.idtchandlerList; DTCWriter : j1939.DTCBufferWriter; arDTC:ARRAY[0..MaxDTC]OF j1939.DTC; END_VAR VAR CONSTANT MaxDTC:UDINT :=100; END_VAR DM1_( xEnable:=TRUE, xDone=> , xBusy=> , xError=> , itfSourceECU:= J1939_ECU, //My CAN J1939 ECU itfDTCHandlerList=> DTCListe , udiDTCCount=> , MalfunctionIndicatorLamp=> , RedStopLamp=>...