8 PA-DIM Variable Extensions

8.1 Overview

Figure 12 provides an overview of the signal model, which is an extension to the types defined in OPC 10000-8.

This specification adds new sub-types to each of the existing VariableTypes in OPC 10000-8.

8.2 AnalogSignalVariableType

8.2.1 Overview

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.

8.2.2 Definition

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.

AnalogSignalVariableType is formally defined in Table 233.

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 234 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 states “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 states “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#002 which states “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#002 which states “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 234.

The child Nodes of the AnalogSignalVariableType have additional Attribute values defined in Table 235.

8.2.3 Engineering units with reference to IEC 61987 CDD

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#004. Figure 15 illustrates this with an example.

8.2.4 MultiStateDictionaryEntryDiscreteType with reference to IEC 61987 CDD

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#003 is in Table 236:

8.3 TemperatureMeasurementVariableType

The TemperatureMeasurementVariableType is a subtype of the AnalogSignalVariableType. It is formally defined in Table 237.

This type defines temperature and is formally defined by ABA927#005.

ABA927#005 defines for a physical system exchanging quantities of heat with two bodies, during a reversible cycle, a positive state quantity characterizing each body and proportional to the quantity of heat exchanged with this body (Temperature).

For SensorType there are two possible IRDIs as target of the HasDictionaryEntry reference, depending on the kind of the connected sensor or chosen by SensorClass In case of RTD (thermoresistance) sensors the IRDI 3:0112/2///61987#ABB088#003 shall be referenced, in case of thermocouple sensors the IRDI 3:0112/2///61987#ABB092#003 shall be referenced. For mapping rules see 8.2.4.

SensorType: ABB088#003 defines classification of RTDs based on material and resistance used.

SensorType: ABB092#003 defines classification of a thermocouple according to the material pair or standard type code.

SensorClass: ABF288#004 defines setting of the sensing element type that is or should be connected to the device.

SensorConnection: ABB091#003 defines classification of an RTD or resistor connection based on the number of wires used. For mapping rules see 8.2.4.

SensorReference: ABB093#003 defines type of reference junction for a thermocouple. For mapping rules see 8.2.4.

The components of TemperatureMeasurementVariableType have additional references which are defined in Table 238.

The child Nodes of the TemperatureMeasurementVariableType have additional Attribute values defined in Table 239.

8.4 FlowMeasurementVariableType

The FlowMeasurementVariableType is a subtype of the AnalogSignalVariableType. It is formally defined in Table 240.

This type defines flow and is formally defined within the subtypes.

LowFlowCutOff: ABJ724#003 defines value of the flow below which the low flow cut-off is switched on, in units of the measuring span, which is fixed to percent. The default value is 1% of the high value of EURange.

FlowDirection: ABN594#003 defines configuration parameter of the value sign of the flow signal for forward flow. For mapping rules see 8.2.4.

The components of FlowMeasurementVariableType have additional references which are defined in Table 241.

The child Nodes of the FlowMeasurementVariableType have additional Attribute values defined in Table 242.

8.5 PressureMeasurementVariableType

The PressureMeasurementVariableType is a subtype of the AnalogSignalVariableType. It is formally defined in Table 243.

This type defines pressure and is formally defined within ABN616#001.

ABN616#001 defines at a point of a surface, scalar quantity equal to the limit of the quotient of the magnitude of the component vector normal to the surface of the force acting at this point, by the area of a surface containing the point, when all the dimensions of that surface tend to zero (Pressure).

8.6 LevelMeasurementVariableType

The LevelMeasurementVariableType is a subtype of the AnalogSignalVariableType. It is formally defined in Table 244.

This type defines level and is formally defined within ABH329#001.

ABH329#002 defines height of process material in a tank, vessel, silo or other container.

8.7 MassFlowRateVariableType

The MassFlowRateVariableType is a subtype of the FlowMeasurementVariableType. It is formally defined in Table 245.

This type defines mass flow and is formally defined within ABB290#005.

ABB290#005 defines mass of material flowing per unit time.

8.8 ActualVolumeFlowRateVariableType

The ActualVolumeFlowRateVariableType is a subtype of the FlowMeasurementVariableType. It is formally defined in Table 246.

This type defines volume flow and is formally defined within ABB291#005.

ABB291#005 defines actual volume of fluid that passes a given point per unit time.

8.9 NormalizedVolumeFlowRateVariableType

The NormalizedVolumeFlowRateVariableType is a subtype of the FlowMeasurementVariableType. It is formally defined in Table 247.

This type defines normalized volume flow and is formally defined within ABB292#005.

ABB292#001 defines volume of material flowing per unit time calculated to base conditions.

8.10 ActualDensityVariableType

The ActualDensityVariableType is a subtype of the AnalogSignalVariableType. It is formally defined in Table 248.

This type defines density and is formally defined within ABA946#004.

ABA946#001 defines density measured under operating conditions.

8.11 ControlVariableType

The ControlVariableType is a subtype of the AnalogSignalVariableType. It is formally defined in Table 249.

This type defines control which is used e.g. for an actuator, positioner.

ABP588#001 defines readback value of the position of an analog final control element within the travel span (between OPEN and CLOSE position). The unit of this value is provided by the EngineeringUnits property.

Setpoint: ABN607#002 defines set point for a valve position.

OperatingDirection: ABD740#003 defines output change to a given input signal. For mapping rules see 8.2.4.

ActuatorType: ABD742#003 defines classification of a positioner according to the actuator for which it can be used. For mapping rules see 8.2.4.

The components of ControlVariableType have additional references which are defined in Table 250.

The child Nodes of the ControlVariableType have additional Attribute values defined in Table 251.

8.12 TotalizerVariableType

The TotalizerVariableType provides means to summarize pulses. The TotalizerVariableType is a subtype of the AnalogSignalVariableType. It is formally defined in Table 252.

This type defines a totalizer value.

For TotalizerVariableType there are more than one possible IRDIs as target of the HasDictionaryEntry reference, depending on the type of the totalized quantity. In case of mass totalization the IRDI 3:0112/2///61987#ABH327#001 shall be referenced, in case of actual volume totalization the IRDI 3:0112/2///61987#ABH328#001 shall be referenced. The related HasDictionaryEntry reference shall be defined after the concrete totalizer type is known.

PulseValue: ABA418#002 defines mass quantity assigned to one pulse. The default value is 1 pulse per 0.1 kg. The unit is fixed to kg.

PulseValue: ABE882#002 defines volume quantity assigned to one pulse. The default value is 1 pulse per 0.1 l. The unit is fixed to l.

PulseWidth: ABA635#003 defines setting of the pulse width. The unit is fixed to ms.

The components of TotalizerVariableType have additional references which are defined in Table 253.

For PulseValue there are more than one possible IRDIs as target of the HasDictionaryEntry reference, depending on the type of the totalized quantity. The dictionary entry for PulseValue shall be 3:0112/2///61987#ABA418#002 for mass flow and 3:0112/2///61987#ABE882#002 for volume flow.

The child Nodes of the TotalizerVariableType have additional Attribute values defined in Table 254.

8.13 AnalyticalMeasurementVariableType

The AnalyticalMeasurementVariableType is a subtype of the AnalogSignalVariableType. It is formally defined in Table 255.

This type defines an analytical measurement value.

8.14 PatMeasurementVariableType

The PatMeasurementVariableType is a subtype of the AnalyticalMeasurementVariableType. It is formally defined in Table 256.

This type defines a PAT measurement value.

PatMatrixDescription: The matrix is an array of all quantities that make up an entity of interest. Quantities are defined by an ID (from a dictionary like CAS or PAT, or defined by user resp. manufacturer) and an associated label.

PatMeasurandDescription: A Measurand is the quantity that is measured. Is it always a part of the matrix. Any quantity of the matrix can become a measurand within one analytical device. Measurands are defined by an ID (from a dictionary like CAS or PAT, or defined by user resp. manufacturer) and an associated label.

3:<DictionaryEntryName> is an optional placeholder for an object of IrdiDictionaryEntryType that defines a predefined group of one or more properties of the classes ABN688 (Concentration measurement variables) or ABN689 (Liquid analysis measurement variables), e.g. ABN628 – mass concentration (per volume) or ABN617 – pH value. ABN688 and ABN689 and their properties are defined in IEC 61987 Common Data Dictionary (CDD). They represent classes of analytical measurement variables.

The components of PatMeasurementVariableType have additional references which are defined in Table 257.

8.15 TwoStateDiscreteSignalVariableType

The TwoStateDiscreteSignalVariableType is used for process variables, that can have two states, and illustrated in Figure 12. It is formally defined in Table 258.

ActualValue: ABN645#001 defines parameter indicating the binary value of a not simulated binary process variable of a device.

SimulationValue: ABN632#001 parameter indicating the simulated value of a binary variable.

SimulationState is defined by IRDI as ABN611#002 which states “parameter indicating the state of simulation” and used also to enable/disable simulation. The value true means ‘Simulation enabled’, and false means ‘Simulation disabled’.

ABN635#001 defines parameter indicating the binary input or output value of a device.

The components of TwoStateDiscreteSignalVariableType have additional references which are defined in Table 259.

The child Nodes of the TwoStateDiscreteSignalVariableType have additional Attribute values defined in Table 260.

8.16 MultiStateDiscreteSignalVariableType

The MultiStateDiscreteSignalVariableType is used for process variables that can have more than two states. It is formally defined in Table 261.

ActualValue: ABN646#002 defines “parameter indicating the discrete value of the not simulated discrete process variable of a device”.

SimulationValue: ABN637#002 defines “parameter indicating the simulated discrete value of a variable, which can have multiple states”.

SimulationState; ABN611#002 defines “parameter indicating the state of simulation” and used also to enable/disable simulation. The value true means ‘Simulation enabled’, and false means ‘Simulation disabled’.

ABN636#002 defines “parameter indicating the discrete input or output value out of multiple state of a device”.

The components of MultiStateDiscreteSignalVariableType have additional references which are defined in Table 262.

The child Nodes of the MultiStateDiscreteSignalVariableType have additional Attribute values defined in Table 263.

8.17 DiscreteSignalVariableType

8.17.1 Overview

The DiscreteSignalVariableType is used for process variables of any data type, Integer, UInteger, Boolean, Structure etc. E.g. the data type Structure can be for aggregation of multiple values into one signal variable. ActualValue contains the unsimulated value during a simulation and SimulationValue contains the value to be used during simulation.

8.17.2 Definition

The DiscreteSignalVariableType is a subtype of the DiscreteItemType defined in OPC 10000-8 and adds optionally ActualValue and SimulationValue components. It is formally defined in Table 264.

ActualValue: ABN644#001 defines “parameter indicating the value of the not simulated discrete process variable of a device”.

SimulationValue: ABN613#001 defines “parameter indicating the simulated value of a variable, which can have multiple states”.

SimulationState: ABN611#002 defines “parameter indicating the state of simulation” and used also to enable/disable simulation. The value true means ‘Simulation enabled’, and false means ‘Simulation disabled’.

The components of DiscreteSignalVariableType have additional references which are defined in Table 265.

The child Nodes of the DiscreteSignalVariableType have additional Attribute values defined in Table 266.

8.18 TwoStateDiscreteControlVariableType

The TwoStateDiscreteControlVariableType is a subtype of the TwoStateDiscreteSignalVariableType. It is formally defined in Table 267.

This type defines control which is used for two state discrete output.

Setpoint: ABP542#001 defines in a control loop, the two-state target value the process value is intended to assume.

OperatingDirection: ABD740#003 defines output change to a given input signal, for example direct or reverse.

FaultState: ABP543#002 defines replacement value of a two-state output in the case of a failure.

ABP541#001 defines two-state readback value in a control loop. The components of TwoStateDiscreteControlVariableType have additional references which are defined in Table 268.

The child Nodes of the TwoStateDiscreteControlVariableType have additional Attribute values defined in Table 269.

8.19 MultiStateDiscreteControlVariableType

The MultiStateDiscreteControlVariableType is a subtype of the MultiStateDiscreteSignalVariableType. It is formally defined in Table 270.

This type defines control which is used for multi state discrete output.

Setpoint: ABP645#002 defines in a control loop, the multi-state target value the process value is intended to assume.

OperatingDirection: ABD740#003 defines output change to a given input signal, for example direct or reverse.

FaultState: ABP651#002 defines replacement value of a multi-state output in the case of a failure.

ABP644#002 defines parameter indicating the discrete readback value in a control loop.

The components of MultiStateDiscreteControlVariableType have additional references which are defined in Table 271.

The child Nodes of the MultiStateDiscreteControlVariableType have additional Attribute values defined in Table 272.