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AF SDK Reference

AFData.InterpolatedValueAsync Method

  • Last UpdatedNov 18, 2025
  • 4 minute read
AFData.InterpolatedValueAsync Method
Returns a single AFValue whose value is interpolated at the passed time.

Namespace:  OSIsoft.AF.Data
Assembly:  OSIsoft.AFSDK (in OSIsoft.AFSDK.dll) Version: 3.1.1.1182

Syntax

public Task<AFValue> InterpolatedValueAsync(
	AFTime time,
	UOM desiredUOM,
	CancellationToken cancellationToken = default
)
Public Function InterpolatedValueAsync ( 
	time As AFTime,
	desiredUOM As UOM,
	Optional cancellationToken As CancellationToken = Nothing
) As Task(Of AFValue)

Dim instance As AFData
Dim time As AFTime
Dim desiredUOM As UOM
Dim cancellationToken As CancellationToken
Dim returnValue As Task(Of AFValue)

returnValue = instance.InterpolatedValueAsync(time, 
	desiredUOM, cancellationToken)
public:
Task<AFValue^>^ InterpolatedValueAsync(
	AFTime time, 
	UOM^ desiredUOM, 
	CancellationToken cancellationToken = CancellationToken()
)
member InterpolatedValueAsync : 
        time : AFTime * 
        desiredUOM : UOM * 
        ?cancellationToken : CancellationToken 
(* Defaults:
        let _cancellationToken = defaultArg cancellationToken new CancellationToken()
*)
-> Task<AFValue> 

Parameters

time
Type: OSIsoft.AF.TimeAFTime
The time at which the value is desired.
desiredUOM
Type: OSIsoft.AF.UnitsOfMeasureUOM
The desired unit of measure for the returned value. If , then the value is returned in the unit of measure specified by the associated attribute's DefaultUOM property.
cancellationToken (Optional)
Type: System.ThreadingCancellationToken
A cancellation token used to abort processing before completion. Passing the default CancellationToken.None will run to completion or until the PIConnectionInfo.OperationTimeOut period elapses.

Return Value

Type: TaskAFValue
Returns a task whose result is the AFValue for the attribute. If AFValue.IsGood returned by the data reference is , then the returned value is converted to the proper UOM and Type. The timestamp of the value will be at the requested time.

Exceptions

ExceptionCondition
AggregateException Asynchronous methods throw AggregateException on failure which will contain one or more exceptions containing the failure.

Remarks

Note Notes to Callers
This method, property, or class is not available in the legacy .NET 3.5 version of the SDK.

Security note Security Note
You must have ReadData security rights to read a data value.

Note Notes to Callers
This call might use a background task to complete some of its work. See the Threading Overview for some matters to consider when execution transitions to another thread.

Important note Important
Asynchronous data calls in AF SDK attempt to do as much work as possible asynchronously. If no work can be done asynchronously, then the SupportedDataMethods will report that asynchronous calls are not supported. If an attribute uses a Formula or other calculated data reference has any input that supports asynchronous calls, then the attribute will support asynchronous calls. When making an asynchronous data call, input data will be acquired asynchronously when possible or synchronously otherwise. Data calls that require partitioning across versions will always fall back to synchronous calls.

Important note Important
Impersonation of AF SDK asynchronous calls relies on the .NET framework's built-in support for flowing execution context across asynchronous points. When making these calls while impersonating, the thread or runtime must be configured to propagate the impersonation across these asynchronous points (see the SecurityContext documentation for details).

Version Information

AFSDK

Supported in: 3.1.1, 3.1.0, 3.0.2, 3.0.1, 3.0.0, 2.10.11, 2.10.5, 2.10.0, 2.10, 2.9.5, 2.9, 2.8.5, 2.8

See Also

In This Topic
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