Table 38 defines the structure of an MDISElectricChokeObjectType. Any vendor specified properties that have been implemented within a project should be documented within a similar format and supplied to the DCS vendor. The addition of vendor specific properties will result in a subtype of the MDISElectricChokeObjectType. When an MDISElectricChokeObjectType Instance is disabled the MDISBaseObjectType defaults are followed.

Table 48 – MDISElectricChokeObjectType Definition

Attribute	Value
BrowseName	MDISElectricChokeObjectType
IsAbstract	False
References	Node Class	BrowseName	DataType	TypeDefinition	Other
Subtype of the MDISBaseObjectType
0:HasComponent	Variable	ActualPosition	0:Float	0:BaseDataVariableType	M, RO
0:HasComponent	Variable	Moving	ChokeMoveEnum	0:BaseDataVariableType	M, RO
0:HasComponent	Variable	CommandRejected	0:Boolean	0:BaseDataVariableType	O, RO
0:HasComponent	Method	Move	See 6.6.4		M
0:HasComponent	Method	Abort	See 6.6.6		M
0:HasComponent	Variable	NonDefeatableOpenInterlock	0:Boolean	0:BaseDataVariableType	O, RO
0:HasComponent	Variable	DefeatableOpenInterlock	0:Boolean	0:BaseDataVariableType	O, RO
0:HasComponent	Variable	NonDefeatableCloseInterlock	0:Boolean	0:BaseDataVariableType	O, RO
0:HasComponent	Variable	DefeatableCloseInterlock	0:Boolean	0:BaseDataVariableType	O, RO
HasInterlock	Variable	<InterlockPlaceholder>	0:Boolean	InterlockVariableType	OP
ConformanceUnits
MDIS Electric Choke Base

ActualPosition – A floating point number that represents the percent open of the choke.

CommandRejected – A flag that, if set to True, indicates that the choke has rejected the last command issued to it. The command could be rejected for a number of reasons. Possible reasons for rejecting a command include:

• Loss of subsea communication reported by the SPCS.
• An active interlock.
• The choke is in the disabled state

Enabled – This Boolean reflects if the choke is available for control. The behaviour follows the MDISBaseObjectType.

Moving – An enumeration indicating the confirmed operation of the choke, (confirmed by SPCS Vendor). Possible status for a choke is moving and stopped.

Move – This Method allows an operator to increase or decrease the size of the opening in the choke. This command moves the choke to the percent value provided as part of the command.

Abort – This Method allows an operator to cancel any currently active move command.

EnableDisable – The choke, when disabled, places a non-defeatable interlock set on Move functionality, in addition to the functionality described in the MDISBaseObjectType.

<InterlockPlaceholder > – The number of interlock Variables will change based on the project and even choke instance. The Variables shall be of InterlockVariableType or a subtype of it. They will be referenced by a HasInterlock Reference and will contain an InterlockFor Reference. Clients can use this information to categorise the interlocks appropriately.

The following Variables indicate that an interlock is set (TRUE) or is not set (FALSE). The Variable shall be the target of an InterlockFor Reference from an instance of an InterlockVariableType that describes the actual interlock.

NonDefeatableOpenInterlock – The open choke command is interlocked and cannot be overridden.

DefeatableOpenInterlock – The open choke command is interlocked and can be overridden.

NonDefeatableCloseInterlock – The close choke command is interlocked and cannot be overridden.

DefeatableCloseInterlock – The close choke command is interlocked and can be overridden.

The MDISElectricChokeObjectType is a subtype of MDISBaseObjectType and inherit the FaultCode Variable. The MDISElectricChokeObjectType defines the standard FaultCodes (for bits 0-15 as defined in 6.2.2) in Table 49. All subtypes of this the MDISElectricChokeObjectType will inherit all FaultCodes defined in this table. Subtypes may define additional FaultCodes in their own table.

Table 49 – MDISElectricChokeObjectType FaultCode Values

Value	Bit no.	Description
FailedToMove	0	The Choke failed to move in response to a command.
CommunicationFault	1	Not possible to operate the choke.

The MDISElectricChokeObjectType defines the standard WarningCodes (for bits 0-15 as defined in 6.2.2) in Table 50. All subtypes of this the MDISElectricChokeObjectType will inherit all WarningCodes defined in this table. Subtypes may define additional WarningCodes in their own table.

Table 50 – MDISElectricChokeObjectType WarningCode Values

Value	Bit no.	Description
SideAProblem	0	There is an issue with the A side of the choke.
SideBProblem	1	There is an issue with the B side of the choke.
UncommandedChange	3	The choke position changed without a command.
CalibrationRequired	4	The choke requires calibration