5.6.7 AxisInformation

This structure defines the information for auxiliary axis for ArrayItemType Variables.

There are three typical uses of this structure:

  1. The step between points is constant and can be predicted using the range information and the number of points. In this case, axisSteps can be set to NULL.

  2. The step between points is not constant, but remains the same for a long period of time (from acquisition to acquisition for example). In this case, axisSteps contains the value of each step on the axis.

  3. The step between points is not constant and changes at every update. In this case, a type like XYArrayType shall be used and axisSteps is set to NULL.

Its elements are defined in Table 31.

Table 31 – AxisInformation DataType structure
NameTypeDescription
AxisInformationstructure

engineeringUnits

 EUInformationHolds the information about the engineering units for a given axis.

eURange

 RangeLimits of the range of the axis

title

 LocalizedTextUser readable axis title, useful when the units are %, the Title can be “Particle size distribution”

axisScaleType

 AxisScaleEnumerationLINEAR, LOG, LN, defined by AxisSteps

axisSteps

 Double[]Specific value of each axis steps, can be set to “Null” if not used

Its representation in the AddressSpace is defined in Table 32.

Table 32 – AxisInformation definition
Attribute Value
BrowseNameAxisInformation
IsAbstractFalse
References NodeClass BrowseName DataType TypeDefinition Other
Subtype of Structure defined in OPC 10000-5.
Conformance Units
Data Access AxisInformationType

When the steps in the axis are constant, axisSteps can be set to “Null” and in this case, the Range limits are used to compute the steps. The number of steps in the axis comes from the parent ArrayItem.ArrayDimensions.