An instance of this Function Block type provides an implementation of
the Auto/Manual Mode state machine defined in Annex F.3.2 of the
NORSOK I-005 Standard for System Control Diagrams.
The Operator Station Select (OSS) and LOCK/UNLOCK functions are
implemented identically as in the
SCDModeIX state machine. This resolves the
following ambiguities in NORSOK I-005:
Figure F.5 of NORSOK I-005 does not show the input and output
signals on the left and right side of the block, respectively.
Some of the state transition arrows in Figure F.5 do not have
arrowheads indicating the direction of the transition.
None of the acronyms defined in Table F.1 are used in Figure
F.5.
The term "Block Safeguarding State" is shown in Table F.1 and
is used without further definition in the text of F.3.2.2, but is not
used in Figure F.5, nor is it defined anywhere else in the Standard.
The influence of the Safeguarding and Outside modes on
Auto/Manual operation is ambiguous. This could be resolved through
the use of an external event-driven block such as SCDModeAMLock to derive appropriate
values and timing for the LOCK, UNLK and LA signals of the SCDModeAM
block.
Enter data for the input variables.
Exercise the FB by clicking on the event inputs.