9 OPC UA VariableTypes ToC Previous Next

9.1 MeasurementValueType ToC Previous Next

The MeasurementValueType is a subtype of BaseDataVariableType. Variables of this type are used to hold one measurement value.

Table 34 – MeasurementValueType Definition

Attribute Value
BrowseName MeasurementValueType
IsAbstract False
ValueRank −2 (−2 = Any)
DataType BaseDataType

Subtype of the BaseDataVariableType defined in [OPC 10000-5]

References NodeClass BrowseName DataType TypeDefinition Other
0:HasProperty Variable PeMeasurementID 0:UInt16 0:PropertyType M, RO
0:HasProperty Variable AccuracyDomain AccuracyDomainEnumeration 0:PropertyType M, RO
0:HasProperty Variable AccuracyClass AccuracyClassEnumeration 0:PropertyType M, RO
0:HasProperty Variable EngineeringUnits 0:EUInformation 0:PropertyType O, RO
0:HasProperty Variable ValueBeforeReset 0:BaseDataType 0:PropertyType O, RO

The BrowseName should be the name of the measurement as defined in Table 21 like “DcCurrent” or “AcReactivePower”.

The PeMeasurementID Variable shall contain the PE measurement ID of this measurement value.

The AccuracyDomain Variable shall contain the PE accuracy domain of this measurement value encoded as AccuracyDomainEnumeration (See Table 53). Table 35 lists the meaning of the possible PE accuracy domain values (see [PE CAP], Table 8).

Table 35 – Values for AccuracyDomain variable

AccuracyDomain Meaning
ACCURACY_DOMAIN_PERCENT_FULL_SCALE The accuracy is given as percent of the full-scale reading. The percentage is coded according to Table 36 and is stored in AccuracyClass.
ACCURACY_DOMAIN_PERCENT_ACTUAL_READING The accuracy is given as percent of the actual reading. The percentage is coded according to Table 36 and is stored in AccuracyClass.
ACCURACY_DOMAIN_IEC The accuracy is given according to IEC 61557-12. The function performance classes for performance measurement and monitoring devices (PMD) without external sensors and system performance classes for PMD with external sensors are coded according to Table 37 and stored in AccuracyClass.
ACCURACY_DOMAIN_EN The accuracy is given as specified in the EN 50470-3, Chapter 8 , encoded according to Table 38 and stored in AccuracyClass.

It is recommended to deliver the measurement values according to accuracy domain ACCURACY_DOMAIN_PERCENT_FULL_SCALE and -_ACTUAL_READING.

The AccuracyClass Variable shall contain the PE accuracy class of this measurement value encoded as AccuracyClassEnumeration (See Table 55). Table 36, Table 37 andTable 38 shows the possible AccuracyClass values if the AccuracyDomain value is ACCURACY_DOMAIN_EN (see Table 35).

Table 38 list the possible PE accuracy class values (see [PE CAP], tables 9, 10 and 11).

Table 36 shows the possible AccuracyClass values if the AccuracyDomain value is ACCURACY_DOMAIN_PERCENT_FULL_SCALE or -_ACTUAL_READING (see Table 35).

Table 36 – Coding of percent values

AccuracyClass Percent Value
ACCURACY_CLASS_0 reserved
ACCURACY_CLASS_1 0,01%
ACCURACY_CLASS_2 0,02%
ACCURACY_CLASS_3 0,05%
ACCURACY_CLASS_4 0,1%
ACCURACY_CLASS_5 0,2%
ACCURACY_CLASS_6 0,5%
ACCURACY_CLASS_7 1%
ACCURACY_CLASS_8 1,5%
ACCURACY_CLASS_9 2%
ACCURACY_CLASS_10 2,5%
ACCURACY_CLASS_11 3%
ACCURACY_CLASS_12 5%
ACCURACY_CLASS_13 10%
ACCURACY_CLASS_14 20%
ACCURACY_CLASS_15 >20%

Table 37 shows the possible AccuracyClass values if the AccuracyDomain value is ACCURACY_DOMAIN_IEC (see Table 35).

Table 37 – Coding of function performance classes and system performance classes (1)

AccuracyClass Function- and System Performance Class
ACCURACY_CLASS_0 reserved
ACCURACY_CLASS_1 0,02
ACCURACY_CLASS_2 0,05
ACCURACY_CLASS_3 0,1
ACCURACY_CLASS_4 0,2
ACCURACY_CLASS_5 0,5
ACCURACY_CLASS_6 1
ACCURACY_CLASS_7 1,5
ACCURACY_CLASS_8 2
ACCURACY_CLASS_9 2,5
ACCURACY_CLASS_10 3
ACCURACY_CLASS_11 5
ACCURACY_CLASS_12 10
ACCURACY_CLASS_13 20
> ACCURACY_CLASS_13 undefined

Table 38 shows the possible AccuracyClass values if the AccuracyDomain value is ACCURACY_DOMAIN_EN (see Table 35).

Table 38 – Coding of function performance classes and system performance classes (2)

AccuracyClass Function- and System Performance Class
ACCURACY_CLASS_0 reserved
ACCURACY_CLASS_1 0,5
ACCURACY_CLASS_2 1,0
ACCURACY_CLASS_3 1,5
ACCURACY_CLASS_4 2,0
ACCURACY_CLASS_5 2,5
ACCURACY_CLASS_6 3,0
>ACCURACY_CLASS_6 undefined

The EngineeringUnits Variable shall contain the mapped UNECE code of the OPC UA EUInformation data type (see [OPC 10000-8], section 5.6.3) for the engineering unit of this measurement value. If the value contains the power factor, no EngineeringUnits Property shall be provided.

If the MeasurementValueType Variable is used as energy counter, the ValueBeforeReset Variable shall be set to the value of the Variable when the energy counter is reset. A reset can be performed using the ResetEnergyCounter Method of the EnergyMeasurementType Object which contains the MeasurementValueType Variable.

After the start of the device the ValueBeforeReset Variable and the value of the MeasurementValueType Variable shall be equal and have the value 0. Further on, the value of the ValueBeforeReset Variable shall not change unless a reset is performed.

The DataType of a MeasurementValueType value shall be one of the following: 0:Int32, 0:Float, 0:Double, AcPeDataType or AcPpDataType.

Instances of MeasurementValueType shall use the same EngineeringUnits as defined in the Interface implemented by the containing EnergyMeasurementType Object.

When reading the value of the MeasurementValueType Variable the status code shall be set to “UncertainSensorValueNotAccurate” if the accuracy of the value cannot be guaranteed for some reason, e.g. the calibration interval is overdue.

Mapping to PROFIenergy properties:

BrowseName PE Service PE Service Data Response Field
PeMeasurementID Get_Measurement_Values_with_Object_Number Measurement_ID
AccuracyDomain Get_Measurement_List_with_Object_Number Accuracy_Domain
AccuracyClass Get_Measurement_List_with_Object_Number Accuracy_Class

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