The following section describes the generic MDISDigitalInstrumentObjectType structure and defines the properties associated with it. Additional sections define a subtype MDISDigitalOutObjectType that allows updates to the digital value. This is in general a vendor and operator independent description, but all users of the MDISDigitalInstrumentObjectType or MDISDigitalOutObjectType can add vendor specific data. The vendor specific data should be defined as part of a subtype of the MDISDigitalInstrumentObjectType or MDISDigitalOutObjectType defined in this document. It is assumed that the subsea system is the Server and host of the instance of MDISDigitalInstrumentObjectType or MDISDigitalOutObjectType. The DCS based system is the Client in the system. It is assumed that all interactions with the instance of the MDISDigitalInstrumentObjectType are initiated by the Client and are directed to the Server.
The following section details the MDIS generic properties for the MDISDigitalInstrumentObjectType; implementation shall ensure adherence to Mandatory [M] aspects in order to comply with the MDIS interface standardisation. Optional [O] may or may not be implemented within a project.
Figure 12 provides an overview of the MDISDigitalInstrumentObjectType as defined by MDIS, including some nested types. This figure includes all items that are inherited from the MDISBaseObjectType.
Figure 12 – MDISDigitalInstrumentObjectType & MDISDigitalOutObjectType & MDISDigitalArbitrationObjectType
Table 19 defines the structure of an MDISDigitalInstrumentObjectType. 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 MDISDigitalInstrumentObjectType.
Table 19 – MDISDigitalInstrumentObjectType Definition
|
Attribute |
Value |
||||
|
BrowseName |
MDISDigitalInstrumentObjectType |
||||
|
IsAbstract |
False |
||||
|
References |
Node Class |
BrowseName |
DataType |
TypeDefinition |
Other |
|
Subtype of the MDISBaseObjectType (see section 6.1.1) |
|
||||
|
0:HasComponent |
Variable |
State |
0:Boolean |
0:BaseDataVariableType |
M, RO |
|
0:HasSubtype |
ObjectType |
MDISDigitalOutObjectType |
|
||
|
0:HasSubtype |
ObjectType |
MDISDigitalArbitrationObjectType |
|
||
|
ConformanceUnits |
|||||
|
MDIS Digital Instrument Base |
|||||
State – The state of the instance of MDISDigitalInstrumentObjectType. This state is represented as a Boolean, where true indicates on and false indicates off.
The MDISDigitalInstrumentObjectType is a subtype of MDISBaseObjectType and inherit the FaultCode Variable. The MDISDigitalInstrumentObjectType defines the standard FaultCodes (for bits 0-15 as defined in 6.2.2) in Table 8. All subtypes of this the MDISDigitalInstrumentObjectType will inherit all FaultCodes defined in this table. Subtypes may define additional FaultCodes in their own table.
Table 20 – MDISDigitalInstrumentObjectType FaultCode Values
|
Value |
Bit no. |
Description |
|
IOFault |
0 |
Instrument has no usable value, there is an I/O fault. |
The MDISDigitalInstrumentObjectType defines the standard WarningCodes (for bits 0-15 as defined in 6.2.2) in Table 9. All subtypes of this the MDISDigitalInstrumentObjectType will inherit all WarningCodes defined in this table. Subtypes may define additional WarningCodes in their own table.
Table 21 – MDISDigitalInstrumentObjectType WarningCode Values
|
Value |
Bit no. |
Description |
|
SideAProblem |
0 |
There is an issue with the A side of this instrument [note this only applies to instrument that are arbitrated] |
|
SideBProblem |
1 |
There is an issue with the B side of this instrument [note this only applies to instrument that are arbitrated] |
|
Discrepancy |
2 |
The values differ [note this only applies to instrument that are arbitrated] |
Table 22 defines the structure of an MDISDigitalOutObjectType. 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 MDISDigitalOutObjectType.
Table 22 – MDISDigitalOutObjectType Definition
|
Attribute |
Value |
||||
|
BrowseName |
MDISDigitalOutObjectType |
||||
|
IsAbstract |
False |
||||
|
References |
Node Class |
BrowseName |
DataType |
TypeDefinition |
Other |
|
Subtype of the MDISDigitalInstrumentObjectType |
|
||||
|
0:HasComponent |
Method |
WriteState |
See 6.4.5 |
M |
|
|
ConformanceUnits |
|||||
|
MDIS Digital Out Base |
|||||
WriteState – This Method allows a Client to change the value of State on an instance of MDISDigitalOutObjectType. The Method will return any errors that occurred on setting the value. The Client shall verify that the State actually changed to confirm the update. If the instrument is disabled, an error Bad_InvalidState shall be returned.
WriteState Method (defined in Table 23) is used to change the state of the State Variable in an instance of MDISDigitalOutObjectType. The WriteState operation applies to the object in the subsea system. The value of the State Variable shall only be updated once the subsea system has provided a new value. For Objects that are used as a command, the value of the State Variable shall be updated directly to the value provided by the State parameter of the Method. Some systems will be able to report any errors immediately others will only be able to report that the operation was not refused. Clients are expected to monitor the State and ensure that the operation completed. If an error occurs after the Method has returned, a Fault flag shall be set and an appropriate FaultCode will be returned. The Fault (and FaultCode) will reset on the next successful WriteState Method invocation.
Signature:
WriteState (
[in] 0:Boolean State);
Table 23 – WriteState Method parameters
|
Argument |
Description |
|
State |
Boolean indicator of the target state of the variable |
Method result codes are defined as part of the Call Service (see OPC 10000-4). They are described in Table 124 for ease of reference.
Comments
The WriteState Method will result in a change the state of the State Variable. The Method will report if any error occurs while writing the state of the Object. Table 24 specifies the AddressSpace representation for the WriteState Method.
Table 24 – WriteState Method AddressSpace Definition
|
Attribute |
Value |
||||
|
BrowseName |
WriteState |
||||
|
References |
Node Class |
BrowseName |
DataType |
TypeDefinition |
Other |
|
0:HasProperty |
Variable |
0:InputArguments |
0:Argument[] |
0:PropertyType |
M |
|
ConformanceUnits |
|||||
|
MDIS Digital Out Base |
|||||
Table 25 defines the structure of an MDISDigitalArbitrationObjectType. 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 MDISDigitalArbitrationObjectType.
Table 25 – MDISDigitalArbitrationObjectType Definition
|
Attribute |
Value |
||||
|
BrowseName |
MDISDigitalArbitrationObjectType |
||||
|
IsAbstract |
False |
||||
|
References |
Node Class |
BrowseName |
DataType |
TypeDefinition |
Other |
|
Subtype of the MDISDigitalInstrumentObjectType |
|
||||
|
0:HasComponent |
Variable |
SourceA |
0:Boolean |
0:BaseDataVariableType |
M, RO |
|
0:HasComponent |
Variable |
SourceB |
0:Boolean |
0:BaseDataVariableType |
M, RO |
|
0:HasComponent |
Variable |
ArbitrationMode |
ArbitrationModeEnum |
0:BaseDataVariableType |
M, RO |
|
0:HasComponent |
Method |
SetArbitrationMode |
Defined in 6.3.7 |
O |
|
|
ConformanceUnits |
|||||
|
MDIS Digital Arbitration |
|||||
The MDISDigitalArbitrationObjectType handles the Selection of two analog sources, SourceA and SourceB. The result of the arbitration is shown in the State. The result can be either a selection of one source as default or forcing of one source (see ArbitrationModeEnum for additional details). The arbitration object will select which instrument is healthy and report it.
SourceA – a Variable that represents the value of the first source of a MDISDigitalArbitrationObjectType.
SourceB – a Variable that represents the value of the second source of a MDISDigitalArbitrationObjectType.
ArbitrationMode – This enumeration provides information about the arbitration mode that is currently used (see section 8.1.10). For a MDISDigitalArbitrationObjectType, the average value does not apply and the High value indicates an “Or” of the two values while a low value indicates an “And’ of the two values.
The MDISDigitalArbitrationObjectType is a subtype of MDISDigitalInstrumentObjectType and inherits the FaultCode Variable. The MDISDigitalArbitrationObjectType defines the standard FaultCodes (for bits 0-15 as defined in 6.2.2) in Table 26 (currently empty, no additional fault codes defined). All subtypes of this the MDISDigitalArbitrationObjectType will inherit all FaultCodes defined in this table. Subtypes may define additional FaultCodes in their own table.
Table 26 – MDISDigitalArbitrationObjectType FaultCode Values
|
Value |
Bit no. |
Description |
|
|
|
|
The MDISDigitalArbitrationObjectType defines the standard WarningCodes (for bits 0-15 as defined in 6.2.2) in Table 27 (currently empty, no additional warning codes defined). All subtypes of this the MDISDigitalArbitrationObjectType will inherit all WarningCodes defined in this table. Subtypes may define additional WarningCodes in their own table.
Table 27 – MDISDigitalArbitrationObjectType WarningCode Values
|
Value |
Bit no. |
Description |
|
|
|
|