An instance of this type provides a time-stamped log for diagnostic events by event name and source, in reverse chronological order. Its input and output variables are defined by the following declarations:

VAR_INPUT
    QI : BOOL; (* Input event qualifier (see FB_TABLE for usage) *)
    SRC : WSTRING; (* Source of event being logged *)
    COND : WSTRING; (* Condition being logged *)
END_VAR
VAR_OUTPUT
    QO : BOOL; (* Output qualifier, (see FB_TABLE for usage) *)
    STATUS : UINT; (* 0=OK,2=TYPE_CONVERSION_ERROR,4=INHIBITED,13=ARRAY_SIZE_ERROR *)
END_VAR

See DRILL_MVCDL for an example of the application of this type.