The AnalogSignalVariableType is used for analog variables representing temperature, flow, pressure, etc.. The AnalogSignalVariableType is a subtype of the AnalogUnitRangeType and adds the optional components ActualValue, SimulationValue and Damping. The model and its subtypes are illustrated in Figure 13.

Figure 13 – AnalogSignal and Signal Object Model

The AnalogSignalVariableType can be used to model any analog signal type. It extends the AnalogUnitRangeType defined in OPC 10000-8 to add additional information such as values for simulation and damping as well as dictionary references.

The ActualValue contains the unsimulated value during a simulation and SimulationValue contains the value to be used during simulation, as illustrated in Figure 14. The Value attribute always represents what is being reported by the Variable.

Figure 14 – Simulation

AnalogSignalVariableType is formally defined in Table 165.

Table 165 – AnalogSignalVariableType definition

Attribute	Value
BrowseName	AnalogSignalVariableType
IsAbstract	False
ValueRank	−2 (−2 = ‘Any’)
DataType	Number
References	NodeClass	BrowseName	DataType	TypeDefinition	Other
Subtype of 0:AnalogUnitRangeType defined in OPC 10000-8, i.e. inheriting the InstanceDeclarations of that Node
0:HasProperty	Variable	0:EngineeringUnits	0:EUInformation	0:PropertyType	M
0:HasComponent	Variable	ActualValue	0:Number{Any}	0:BaseDataVariableType	O
0:HasComponent	Variable	SimulationValue	0:Number{Any}	0:BaseDataVariableType	O
0:HasComponent	Variable	SimulationState	0:Boolean	0:BaseDataVariableType	O
0:HasProperty	Variable	Damping	0:Float	0:PropertyType	O
0:HasDictionaryEntry	Object	3:0112/2///61987#ABN634#001		0:IrdiDictionaryEntryType
Conformance Units
PA-DIM AnalogSignalVariableType
PA-DIM AnalogSignalVariable Simulation
PA-DIM AnalogSignalVariable Damping

AnalogSignalVariableType also extends AnalogUnitRangeType by providing additional references. These references provide dictionary entries for all of the variables defined by this addition as well as dictionary references for fields in the parent AnalogUnitRangeType. See Table 166 for a complete definition.

The VariableType is extended in this definition to include the dictionary reference. The dictionary provides an additional description of Value which is copied here for clarity – “ABN634#001 defines parameter indicating the input or output value of a device using the units of measure of the process variable.”

EngineeringUnits is the engineering unit associated with the value attribute of AnalogSignalVariableType, and as well with ActualValue and SimulationValue. It overwrites the EngineeringUnits property inherited from AnalogUnitRangeType.

ActualValue reflects the measured value independent of the simulation state. It is further described by dictionary entry ABN644#001 which defines “parameter indicating the value of the not simulated process variable of a device using the units of measure of the process variable”.

SimulationValue provides a value that substitutes Value if the simulation is enabled. It is further described by dictionary entry ABN613#001 which defines “parameter indicating the simulated value of a variable using the units of measure of the simulated variable”.

Damping provides a value in seconds that is used to flatten changes in the value. It is further described by dictionary entry ABH526#001 which defines “for the output of a first-order system forced by a step or an impulse, the time required to complete 63.2% of the total rise or decay at any instant during the process”.

SimulationState is defined by IRDI as ABN611#001 which defines “parameter indicating the state of simulation”. The value true means ‘Simulation enabled’, and false means ‘Simulation disabled’.

The components of AnalogSignalVariableType have additional references which are defined in Table 166.

Table 166 – AnalogSignalVariableType additional References

SourceBrowsePath	Reference Type	Is Forward	TargetBrowsePath
0:EngineeringUnits	0:HasDictionaryEntry	True	3:0112/2///61987#ABA968#002
ActualValue	0:HasDictionaryEntry	True	3:0112/2///61987#ABN644#001
SimulationValue	0:HasDictionaryEntry	True	3:0112/2///61987#ABN613#001
Damping	0:HasDictionaryEntry	True	3:0112/2///61987#ABH526#002
SimulationState	0:HasDictionaryEntry	True	3:0112/2///61987#ABN611#001

The child Nodes of the AnalogSignalVariableType have additional Attribute values defined in Table 167.

Table 167 – AnalogSignalVariableType Attribute values for child Nodes

BrowsePath	Value Attribute
SimulationState	False
Damping	1.0

The Property EngineeringUnits – inherited from AnalogUnitRangeType (see OPC 10000-8 Amendment 1) – shall be used to define the unit for the AnalogSignalVariableType instance and also for its ActualValue and SimulationValue component Variables.

In addition, each EngineeringUnits Property shall provide a HasDictionaryEntry reference to the IEC Common Data Dictionary entry for "unit of measure" which is 3:0112/2///61987#ABA968#002. Figure 15 illustrates this with an example.

Figure 15 – EngineeringUnits Property with HasDictionaryEntry Reference

If MultiStateDictionaryEntryDiscreteType Variables reference an IEC 61987 CDD PROPERTY with a Value list, the following mapping applies:

• For each possible element in the "Value list" map the Preferred name of the element to the "EnumValues" Property.
• For each possible element in the "Value list" map the IRDI of the element to the "EnumDictionaryEntries" Property.

An example for the SensorConnection Property with IRDI 0112/2///61987#ABB091#002 is in Table 168:

Table 168 – Example of a MultiStateDictionaryEntryDiscreteType with IEC 61987 CDD reference

IEC 61987 CDD	ECLASS	OPC UA mapping
"Value list" attribute	"Value list" attributeto be defined	"EnumValues" Property	"EnumDictionaryEntries" Property
0112/2///61987#ABL113 - 4-wire	0173-1#02-CCCnnn#00n	[0] -> "4-wire"	[0] -> 3:0112/2///61987#ABL113#001
0112/2///61987#ABL114 - 3-wire	0173-1#02-CCCnnn#00n	[1] -> "3-wire"	[1] -> 3:0112/2///61987#ABL114#001
0112/2///61987#ABL115 - 2-wire	0173-1#02-CCCnnn#00n	[2] -> "2-wire"	[2] -> 3:0112/2///61987#ABL115#001
0112/2///61987#ABI407 – others	0173-1#02-CCCnnn#00n	[3] -> "others"	[3] -> 3:0112/2///61987#ABI407#004