Class VariableHistorian

constructor

• new VariableHistorian(
      node: UAVariable,
      options: IVariableHistorianOptions,
  ): VariableHistorian

  Parameters

  • node: UAVariable
  • options: IVariableHistorianOptions

  Returns VariableHistorian

Readonlynode

extractDataValues

• extractDataValues(
      historyReadRawModifiedDetails: ReadRawModifiedDetails,
      maxNumberToExtract: number,
      isReversed: boolean,
      reverseDataValue: boolean,
      callback: CallbackT<DataValue[]>,
  ): void

  Extract a series of dataValue from the History database for this value

  Parameters

  • historyReadRawModifiedDetails: ReadRawModifiedDetails
  • maxNumberToExtract: number
  • isReversed: boolean
  • reverseDataValue: boolean
  • callback: CallbackT<DataValue[]>

  Returns void

findBoundAfter

• findBoundAfter(date: Date): DataValue | null

  Find the oldest raw data value with a sourceTimestamp strictly after date.

  See findBoundBefore.

  Parameters

  • date: Date

  Returns DataValue | null

findBoundBefore

• findBoundBefore(date: Date): DataValue | null

  Find the most recent raw data value with a sourceTimestamp strictly before date.

  Used to compute a Bounding Value (OPC 10000-11 6.5.3.2 and 3.1.2) when a HistoryRead with ReadRawModifiedDetails.returnBounds set finds no raw value exactly at the start or end of the requested time domain. Returns null when no such value exists.

  Optional: a historian that does not implement it causes the bound to be reported as Bad_BoundNotSupported instead of being computed.

  Parameters

  • date: Date

  Returns DataValue | null

push

• push(newDataValue: DataValue): Promise<void>

  push a new value into the history for this variable the method should take a very small amount of time and not directly write to the underlying database

  Parameters

  • newDataValue: DataValue

  Returns Promise<void>