7.5 VariableTypes

7.5.1 Overview

The section defines common variable types that are used by multiple section of the ISA specification (i.e. equipment and physical assets etc.) In some cases these types define a generic version of the variable that will be further customized in the specific section, i.e. equipment or physical asset variable section.

The variable types defined in the following sections make use of reference types that are defined in section 0. These reference types provide specific semantic information. To fully understand the Variable or Object models it may be required to review these reference descriptions.

7.5.2 ISA95ClassPropertyType

The ISA95ClassPropertyType is an abstract VariableType that cannot be used directly. It must be subtyped to be used. It is a subtype of BaseDataVariableType defined in OPC 10000-5.

This VariableType is used to define an ISA95ClassProperty for an ISA95Class.

The Key defines an Id to differentiate between the different values. When multiple values are stored to the Value attribute this ISA95Attribute is used. For example a value may be a series of numbers, such as a series of peak values from a spectrometer.

7.5.3 ISA95PropertyType

The ISA95PropertyType is an abstract VariableType that cannot be used directly. It must be subtyped to be used. It is a subtype of BaseDataVariableType defined in OPC 10000-5.

This VariableType is used to define an ISA95Property for an ISA95Object.

Key defines an Id to differentiate between the different values. When multiple values are stored to Value attribute this ISA95Attribute is used. For example a value may be a series of numbers, such as a series of peak values from spectrometer.

7.5.4 ISA95TestResultType

The ISA95TestResultdType is a concrete VariableType that can be used directly. It is a subtype of BaseDataVariableType defined in OPC 10000-5.

This VariableType indicates the test results. Value attribute of this DataVariable is structured data. However, each element of the structure can be accessed via Properties.

Note: The Variable has a DataType of Structure which is generic and must be assigned to a defined sub-type before it is transmitted on the wire. The generic Structure DataType results in an ExtensionObject being placed on the wire. The default defined sub-type is either ISA95TestResultDataType or ISA95TestResultMeasurementDataType depending on the nature of the data. If a different structure is used, it shall include all of the fields defined in this structure and the defined sub-type of this variable type shall also include any additional fields that are in the structure as separate variables.

Id is an identifier of the Test Result. This field can be used to reference the actual result.

ResultDescription is an additional information or description of the test result.

TestDate is the date and time of the test. This Time is used to determine when a test expires, it is server specific as to whether it is a test start time or end time, but it should be consistent in all cases.

Result is the result of the test (further defined in subtypes).

ResultUnitOfMeasure is the unit of measure of the associated test result. It is defined as a structure to allow either a EUInformation or a measurement code (clause 6.3.8) to be reported.

Expiration is the date of the expiration of the test result.