Data type __SYSTEM.ExceptionCode

An IEC variable for an exception has the data type __SYSTEM.ExceptionCode. Exceptions such as these are caught, for example, by __TRY, __CATCH, __FINALLY, __ENDTRY, which is used for targeted exception handling.

You can also use the ExceptionCode data type to classify errors or exceptions that occur in the application code itself and then log them, for example. An example can be found at the bottom of this page.

In addition, the Tc2_System library contains the F_RaiseException function, which enables a specific exception code to be thrown.

If you use the F_RaiseException() function outside a __TRY block, the exception is caught by TwinCAT Exception Handling and the execution of the controller is stopped.

Data type  __SYSTEM.ExceptionCode:

TYPE ExceptionCode :
(
    RTSEXCPT_UNKNOWN                                := 16#FFFFFFFF,
    RTSEXCPT_NOEXCEPTION                            := 16#00000000,
    RTSEXCPT_WATCHDOG                               := 16#00000010,
    RTSEXCPT_HARDWAREWATCHDOG                       := 16#00000011,
    RTSEXCPT_IO_CONFIG_ERROR                        := 16#00000012,
    RTSEXCPT_PROGRAMCHECKSUM                        := 16#00000013,
    RTSEXCPT_FIELDBUS_ERROR                         := 16#00000014,
    RTSEXCPT_IOUPDATE_ERROR                         := 16#00000015,
    RTSEXCPT_CYCLE_TIME_EXCEED                      := 16#00000016,
    RTSEXCPT_ONLCHANGE_PROGRAM_EXCEEDED             := 16#00000017,
    RTSEXCPT_UNRESOLVED_EXTREFS                     := 16#00000018,
    RTSEXCPT_DOWNLOAD_REJECTED                      := 16#00000019,
    RTSEXCPT_BOOTPROJECT_REJECTED_DUE_RETAIN_ERROR  := 16#0000001A,
    RTSEXCPT_LOADBOOTPROJECT_FAILED                 := 16#0000001B,
    RTSEXCPT_OUT_OF_MEMORY                          := 16#0000001C,
    RTSEXCPT_RETAIN_MEMORY_ERROR                    := 16#0000001D,
    RTSEXCPT_BOOTPROJECT_CRASH                      := 16#0000001E,
    RTSEXCPT_BOOTPROJECTTARGETMISMATCH              := 16#00000021,
    RTSEXCPT_SCHEDULEERROR                          := 16#00000022,
    RTSEXCPT_FILE_CHECKSUM_ERR                      := 16#00000023,
    RTSEXCPT_RETAIN_IDENTITY_MISMATCH               := 16#00000024,
    RTSEXCPT_IEC_TASK_CONFIG_ERROR                  := 16#00000025,
    RTSEXCPT_APP_TARGET_MISMATCH                    := 16#00000026,
    RTSEXCPT_ILLEGAL_INSTRUCTION                    := 16#00000050,
    RTSEXCPT_ACCESS_VIOLATION                       := 16#00000051,
    RTSEXCPT_PRIV_INSTRUCTION                       := 16#00000052,
    RTSEXCPT_IN_PAGE_ERROR                          := 16#00000053,
    RTSEXCPT_STACK_OVERFLOW                         := 16#00000054,
    RTSEXCPT_INVALID_DISPOSITION                    := 16#00000055,
    RTSEXCPT_INVALID_HANDLE                         := 16#00000056,
    RTSEXCPT_GUARD_PAGE                             := 16#00000057,
    RTSEXCPT_DOUBLE_FAULT                           := 16#00000058,
    RTSEXCPT_INVALID_OPCODE                         := 16#00000059,
    RTSEXCPT_MISALIGNMENT                           := 16#00000100,
    RTSEXCPT_ARRAYBOUNDS                            := 16#00000101,
    RTSEXCPT_DIVIDEBYZERO                           := 16#00000102,
    RTSEXCPT_OVERFLOW                               := 16#00000103,
    RTSEXCPT_NONCONTINUABLE                         := 16#00000104,
    RTSEXCPT_PROCESSORLOAD_WATCHDOG                 := 16#00000105,
    RTSEXCPT_FPU_ERROR                              := 16#00000150,
    RTSEXCPT_FPU_DENORMAL_OPERAND                   := 16#00000151,
    RTSEXCPT_FPU_DIVIDEBYZERO                       := 16#00000152,
    RTSEXCPT_FPU_INEXACT_RESULT                     := 16#00000153,
    RTSEXCPT_FPU_INVALID_OPERATION                  := 16#00000154,
    RTSEXCPT_FPU_OVERFLOW                           := 16#00000155,
    RTSEXCPT_FPU_STACK_CHECK                        := 16#00000156,
    RTSEXCPT_FPU_UNDERFLOW                          := 16#00000157,
    RTSEXCPT_VENDOR_EXCEPTION_BASE                  := 16#00002000,
    RTSEXCPT_USER_EXCEPTION_BASE                    := 16#00010000
) UDINT ;
END_TYPE

VAR_GLOBAL
    nCheckBounds              : INT;
    nCheckBounds_OutOfBounds  : INT;
    myException               : __SYSTEM.ExceptionCode;
END_VAR

// Implicitly generated code : DO NOT EDIT
FUNCTION CheckBounds : DINT
VAR_INPUT
    index, lower, upper       : DINT;
END_VAR

// Only an implementation suggestion
{noflow}
GVL_Exc.nCheckBounds := GVL_Exc.nCheckBounds + 1;

// Index too low
IF index < lower THEN
    CheckBounds                      := lower;
 
    // Option 1: Log exception code in global exception variable
    GVL_Exc.myException              := __SYSTEM.ExceptionCode.RTSEXCPT_ARRAYBOUNDS;
 
    // Option 2: Increment global "out of bounds" counter
    GVL_Exc.nCheckBounds_OutOfBounds := GVL_Exc.nCheckBounds_OutOfBounds + 1;
 
    // Option 3: Raise exception
    // Please note: To avoid a runtime exception and thus a runtime stop, F_RaiseException could be used within __TRY / __CATCH.
    F_RaiseException(__SYSTEM.ExceptionCode.RTSEXCPT_ARRAYBOUNDS);
 
// Index too high
ELSIF index > upper THEN
    CheckBounds                      := upper;
 
    // Option 1: Log exception code in global exception variable
    GVL_Exc.myException              := __SYSTEM.ExceptionCode.RTSEXCPT_ARRAYBOUNDS;
 
    // Option 2: Increment global "out of bounds" counter
    GVL_Exc.nCheckBounds_OutOfBounds := GVL_Exc.nCheckBounds_OutOfBounds + 1;
 
    // Option 3: Raise exception
    // Please note: To avoid a runtime exception and thus a runtime stop, F_RaiseException could be used within __TRY / __CATCH.
    F_RaiseException(__SYSTEM.ExceptionCode.RTSEXCPT_ARRAYBOUNDS);
 
// Index OK
ELSE 
    CheckBounds := index;
END_IF

See also:

• Bound Checks (POU CheckBounds)