VhsDatastoreInterface Methods

The VhsDatastoreInterface object contains the following methods:

AddHistoryPoint
AddHistoryPointEx
Close
ContinueHistoryRead
ContinueHistoryReadEx
CreatePointIterator
CreateRollupIterator
CreateValueIterator

CreateValueIteratorReverse
DeleteHistoryPoint
DeleteHistoryValueEx
GetNamedArrayValues
GetNamedArrayValuesEx
GetPointStats
GetPointStatsEx
ListHistoryPointsEx

ListHistoryValuesEx
Open
StartHistoryRead
StartHistoryReadEx
StoreHistoryList
StorePointHistory
StorePointHistoryEx
UpdateHistoryValueEx

Methods ending in Ex represent extended messaging functionality, for example, getting and storing the Long Point Id in the entry record, and getting and storing extended value fields, e.g., Rollup, Status, TimeStamp, UserStats, and Value fields.

A description for each variant object can be found in VhsClient Helper Objects.

AddHistoryPoint

The AddHistoryPoint method adds a new history point to a VHS datastore.

Syntax

AddHistoryPoint(Request As Variant, Response As Variant) As Integer

Parameters

Parameter	Required	Description	Variant
Request	Yes	The request object that contains the parameters for this method.	AddHistoryPointReq
Response	Yes	The response object that contains the output of this method.	AddHistoryPointResp

Remarks

Returns 0 if successful and a non-zero value if an error occurred. Adding a tag that has already been added will not generate an error. Adding a new point to the VHS datastore in this way does not result in the corresponding CVS actually recording new values to the VHS for the point. History must be enabled in the PNT for the CVS to process new values and log them to the VHS. This method is not generally used.

Example

The following example adds a new point to CYGDEMO.UIS and alerts the user of any errors.

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AddHistoryPoint

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Sub VhsAddHistoryPoint()
    Dim VhsDatastoreInterface, req, resp, tag
    Set VhsDatastoreInterface  = CreateObject("CxVhsLib.VhsDatastoreInterface.1")
    Set req = CreateObject("CxVhsLib.AddHistoryPointReq")
    Set resp = CreateObject("CxVhsLib.AddHistoryPointResp")
    Set tag = CreateObject("CxVhsLib.HistoryTagString")
    VhsDatastoreInterface.Open("C:\CygNet\Services\VHS\")
     
    'The point to be created
    tag.TagString = "CYGDEMO.UIS.00001235"
    req.TagString = tag 
     
    VhsDatastoreInterface.AddHistoryPoint req, resp
     
    If resp.Error <> 0 Then
        edtMessageBox.Text = "Error number" & resp.Error
    Else
        edtMessageBox.Text = "Completed successfully"
    End If
End Sub

AddHistoryPointEx

The AddHistoryPointEx method adds a new history point to a VHS datastore.

Syntax

AddHistoryPointEx(Request As Variant, Response As Variant) As Integer

Parameters

Parameter	Required	Description	Variant
Request	Yes	The request object that contains the parameters for this method.	AddHistoryPointReqEx
Response	Yes	The response object that contains the output of this method.	AddHistoryPointRespEx

Remarks

Example

The following example adds a new point to CYGDEMO.UIS and alerts the user of any errors.

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AddHistoryPointEx

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Sub VhsAddHistoryPointEx()
    Dim VhsDatastoreInterface, req, resp, tag
    Set VhsDatastoreInterface = CreateObject("CxVhsLib.VhsDatastoreInterface.1")
    Set req = CreateObject("CxVhsLib.AddHistoryPointExReq")
    Set resp = CreateObject("CxVhsLib.AddHistoryPointExResp")
    Set tag = CreateObject("CxVhsLib.HistoryTagStringEx")
    VhsDatastoreInterface.Open("C:\CygNet\Services\VHS\")
     
    'The point to be created
    tag.TagString = "CYGDEMO.UIS.00001235:MY_LONG_ID"
    req.TagStringEx = tag
    req.ExpirationDays = 9999
    
    VhsDatastoreInterface.AddHistoryPointEx req, resp
     
    If resp.Error <> 0 Then
        edtMessageBox.Text = "Error number " & resp.Error
    Else
        edtMessageBox.Text = "Completed successfully"
    End If
End Sub

Close

The Close method closes the VHS datastore.

Syntax

Close() As Boolean

Remarks

Returns 0 if successful and a non-zero value if the closure failed.

Example

The following example closes the VHS.

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Sub VhsClose()
    VhsDatastoreInterface.Close
End Sub

ContinueHistoryRead

The ContinueHistoryRead method is used after StartHistoryRead for successive calls until all history entries have been returned.

Syntax

ContinueHistoryRead(Request As Variant, Response As Variant) As Integer

Parameters

Parameter	Required	Description	Variant
Request	Yes	The request object that contains the parameters for this method.	ContinueHistoryReadReq
Response	Yes	The response object that contains the output of this method.	HistoryReadResp

Remarks

When the Response object’s Error variable is equal to 10, the end of the history values has been reached.

Example

The following example reads two more values from the history. It uses a global variable, g_Restart, that was set in a StartHistoryRead method.

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ContinueHistoryRead

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Sub VhsContinueHistoryRead()
    Dim VhsDatastoreInterface, req, resp
    Set VhsDatastoreInterface  = CreateObject("CxVhsLib.VhsDatastoreInterface.1")
    Set req = CreateObject("CxVhsLib.ContinueHistoryReadReq")
    Set resp = CreateObject("CxVhsLib.HistoryReadResp")
    VhsDatastoreInterface.Open("C:\CygNet\Services\VHS\")
     
    req.Count = 2
    req.Restart = g_Restart  
     
    VhsDatastoreInterface.ContinueHistoryRead req, resp
     
    g_Restart = resp.Restart
     
    If resp.Error = 10 Then
        edtMessageBox.Text = "End of history has been reached"
    Elseif resp.Error <> 0 Then
        edtMessageBox.Text = "Error number " & resp.Error
    Else
        edtMessageBox.Text = "Completed successfully"
        For i = 0 To resp.Count - 1
            ListBox2.AddString(i & " - " & resp.entry(i).Status & " - " & resp.entry(i).TimeStamp & " - " & resp.entry(i).Value)
        Next  
    End If
End Sub

ContinueHistoryReadEx

The ContinueHistoryReadEx method is used after StartHistoryReadEx for successive calls until all history entries have been returned.

Syntax

ContinueHistoryReadEx(Request As Variant, Response As Variant) As Integer

Parameters

Parameter	Required	Description	Variant
Request	Yes	The request object that contains the parameters for this method.	ContinueHistoryReadExReq
Response	Yes	The response object that contains the output of this method.	HistoryReadExResp

Remarks

When the Response object’s Error variable is equal to 10, the end of the history values has been reached.

Example

The following example reads two more values from the history. It uses a global variable, g_Restart, that was set in a StartHistoryReadEx method.

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ContinueHistoryReadEx

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Sub VhsContinueHistoryReadEx()
    Dim VhsDatastoreInterface, req, resp
    Set VhsDatastoreInterface  = CreateObject("CxVhsLib.VhsDatastoreInterface.1")
    Set req = CreateObject("CxVhsLib.ContinueHistoryReadExReq")
    Set resp = CreateObject("CxVhsLib.HistoryReadExResp")
    VhsDatastoreInterface.Open("C:\CygNet\Services\VHS\")
     
    req.Count = 3
    req.Restart = g_Restart  
     
    VhsDatastoreInterface.ContinueHistoryReadEx req, resp
     
    g_Restart = resp.Restart
     
    If resp.Error = 10 Then
        edtMessageBox.Text = "End of history"
    Elseif resp.Error <> 0 Then
        edtMessageBox.Text = "Error number " & resp.Error
    Else
        edtMessageBox.Text = "Completed successfully"
        For i = 0 To resp.Count - 1
            ListBox2.AddString(i & " - " & resp.entry(i).Status & " - " & resp.entry(i).UserStatus & " - " & resp.entry(i).TimeStamp & " - " & resp.entry(i).Value)
        Next
    End If
End Sub

CreatePointIterator

The CreatePointIterator method is used to create a point iterator object specifically for the VHS datastore that the VhsDatastoreInterface is connected to. You can’t use iterator objects for the VhsDatastoreInterface without using the methods in VhsDatastoreInterface to create the iterators.

Syntax

CreatePointIterator([OrderByPointIdLong As Boolean = False].[Unused As Boolean = False]) As PointIterator

Parameters

Parameter	Required	Description
OrderByPointIdLong	No	Set to any nonzero number to sort the points alphabetically by Long ID, or zero to leave them unsorted. The default value is False.
Unused	No	This can be any number, but it doesn’t affect anything. The default value is False.

Example

The following example shows how to create a point iterator.

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CreatePointIterator

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Sub VhsDataFileConnect()
    Dim VhsDatastoreInterface
    Dim VhsPointIterator
    Set VhsDatastoreInterface = CreateObject("CxVhsLib.VhsDatastoreInterface")
    VhsDatastoreInterface.Open("C:\CygNet\Services\VHS\")
     
    Set VhsPointIterator = VhsDatastoreInterface.CreatePointIterator()
End Sub

CreateRollupIterator

The CreateRollupIterator method creates a rollup iIterator specifically tailored for the VHS datastore opened by this VhsDatastoreInterface.

Syntax

CreateRollupIterator(TagString As String, TimeStampEarliest As Date, TimeStampLatest As Date, RollupType As Integer, RollupUnits As Integer, RollupPeriod As Integer, TopOfDayHour As Integer) As RollupIterator

Parameters

Parameter	Required	Description
TagString	Yes	The point tag from which data is being retrieved in valid CygNet tag string format.
TimeStampEarliest	Yes	The starting date of the retrieval period. Enter 0 for the date of the earliest timestamp.
TimeStampLatest	Yes	The ending date of the retrieval period. Enter 0 for the date of the latest timestamp.
RollupType	Yes	Specifies the rollup type of the value entry. The possible values are listed on the CxRollupType enum table.
RollupUnits	Yes	Specifies the rollup units of the value entry. This refers to time increments, such as seconds, minutes, hours, or days. The possible values are listed on the CxRollupUnits enum table.
RollupPeriod	Yes	Specifies the rollup period of the value entry. Rollup period refers to the quantity of units in a period. For example, to rollup 30 days, the RollupPeriod is 30 and the RollupUnit is "days."
TopOfDayHour	Yes	Specifies the offset value to use if the subunit to the major unit (i.e. hours to a day) does not start at the time unit expected. For example, to accommodate contract days starting at 5 AM, the TopOfDayHour would be 5 (indicating 5 hours from midnight).

Example

The following example shows how to create a rollup iterator.

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VhsRollupIterator

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Sub VhsDataFileConnect()
    Dim VhsDatastoreInterface
    Dim VhsHistoryTagEx
    Dim VhsRollupIterator
     
    Set VhsDatastoreInterface = CreateObject("CxVhsLib.VhsDatastoreInterface")
    VhsDatastoreInterface.Open("C:\CygNet\Services\VHS\")
     
    Set VhsHistoryTagEx = CreateObject("CxVhsLib.HistoryTagStringEx")
    VhsHistoryTagEx.Site = "TEST"
    VhsHistoryTagEx.Service= "VHS"
    VhsHistoryTagEx.PointId= "TESTER"
    VhsHistoryTagEx.PointIdLong= "TESTER_LONG"
     
    Set VhsRollupIterator = VhsDatastoreInterface.CreateRollupIterator(VhsHistoryTagEx.TagString,0,0,0,0,0,0)
End Sub

CreateValueIterator

The CreateValueIterator method creates a value iterator specifically tailored for the VHS datastore opened by this VhsDatastoreInterface.

Syntax

CreateValueIterator(TagString As String, TimeStampEarliest As Date, TimeStampLatest As Date,[IncludeDeleted As Boolean = False]) As ValueIterator

Parameters

Parameter	Required	Description
TagString	Yes	The point tag from which data is being retrieved in valid CygNet tag string format.
TimeStampEarliest	Yes	The starting date of the retrieval period. Enter 0 for the date of the earliest timestamp.
TimeStampLatest	Yes	The ending date of the retrieval period. Enter 0 for the date of the latest timestamp.
IncludeDeleted	No	Indicates whether to include deleted records (1) or not (0). The default value is False. It should accept (True) or (False), but (1) and (0) also work.

Example

The following example shows how to create a value iterator.

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CreateValueIterator

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Sub VhsDataFileConnect()
    Dim VhsDatastoreInterface
    Dim VhsHistoryTagEx
    Dim VhsValueIterator
     
    Set VhsDatastoreInterface = CreateObject("CxVhsLib.VhsDatastoreInterface")
    VhsDatastoreInterface.Open("C:\CygNet\Services\VHS\")
     
    Set VhsHistoryTagEx = CreateObject("CxVhsLib.HistoryTagStringEx")
    VhsHistoryTagEx.Site = "TEST"
    VhsHistoryTagEx.Service= "VHS"
    VhsHistoryTagEx.PointId= "TESTER"
    VhsHistoryTagEx.PointIdLong= "TESTER_LONG"
     
    Set VhsValueIterator = VhsDatastoreInterface.CreateValueIterator(VhsHistoryTagEx.TagString,0,0)
End Sub

CreateValueIteratorReverse

The CreateValueIteratorReverse method creates a reverse value iterator specifically tailored for the VHS datastore opened by this VhsDatastoreInterface.

Syntax

CreateValueIteratorReverse(TagString As String, TimeStampEarliest As Date, TimeStampLatest As Date,[IncludeDeleted As Boolean = False]) As ValueIteratorReverse

Parameters

Parameter	Required	Description
TagString	Yes	The point tag from which data is being retrieved in valid CygNet tag string format.
TimeStampEarliest	Yes	The starting date of the retrieval period. Enter 0 for the date of the earliest timestamp.
TimeStampLatest	Yes	The ending date of the retrieval period. Enter 0 for the date of the latest timestamp.
IncludeDeleted	No	Indicates whether to include deleted records (1) or not (0). The default value is False. It should accept (True) or (False), but (1) and (0) also work.

Example

The following example shows how to create a reverse value iterator.

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CreateValueIteratorReverse

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Sub VhsDataFileConnect()
    Dim VhsDatastoreInterface
    Dim VhsHistoryTagEx
    Dim VhsValueIteratorReverse
     
    Set VhsDatastoreInterface = CreateObject("CxVhsLib.VhsDatastoreInterface")
    VhsDatastoreInterface.Open("C:\CygNet\Services\VHS\")
     
    Set VhsHistoryTagEx = CreateObject("CxVhsLib.HistoryTagStringEx")
    VhsHistoryTagEx.Site = "TEST"
    VhsHistoryTagEx.Service= "VHS"
    VhsHistoryTagEx.PointId= "TESTER"
    VhsHistoryTagEx.PointIdLong= "TESTER_LONG"
     
    Set VhsValueIteratorReverse = VhsDatastoreInterface.CreateValueIteratorReverse(VhsHistoryTagEx.TagString,0,0)
End Sub

DeleteHistoryPoint

The DeleteHistoryPoint method deletes a point from the VHS datastore.

Syntax

DeleteHistoryPoint(Request As Variant, Response As Variant) As Integer

Parameters

Parameter	Required	Description	Variant
Request	Yes	The request object that contains the parameters for this method.	DeleteHistoryPointReq
Response	Yes	The response object that contains the output of this method.	DeleteHistoryPointResp

Remarks

Returns 0 if successful and a non-zero value if an error occurred.

Example

The following example deletes CYGDEMO.UIS.00001235 from the VHS.

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DeleteHistoryPoint

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Sub VhsDeleteHistoryPoint()
    Dim VhsDatastoreInterface, req, resp, tag
    Set VhsDatastoreInterface  = CreateObject("CxVhsLib.VhsDatastoreInterface.1")
    Set req = CreateObject("CxVhsLib.DeleteHistoryPointReq")
    Set resp = CreateObject("CxVhsLib.DeleteHistoryPointResp")
    Set tag = CreateObject("CxVhsLib.HistoryTagString")
    VhsDatastoreInterface.Open("C:\CygNet\Services\VHS\")
     
    'The point to be deleted
    tag.TagString = "CYGDEMO.UIS.00001235"
    req.TagString = tag
     
    VhsDatastoreInterface.DeleteHistoryPoint req, resp
     
    'Error handling
    If resp.Error <> 0 Then
    edtMessageBox.Text = "Error number " & resp.Error
    Else
    edtMessageBox.Text = "Completed successfully"
    End If
End Sub

DeleteHistoryValueEx

The DeleteHistoryValueEx method deletes a history value from a point in the VHS datastore.

Syntax

DeleteHistoryValueEx(Request As Variant, Response As Variant) As Integer

Parameters

Parameter	Required	Description	Variant
Request	Yes	The request object that contains the parameters for this method.	DeleteHistoryValueExReq
Response	Yes	The response object that contains the output of this method.	DeleteHistoryValueExResp

Remarks

Returns 0 if successful and a non-zero value if an error occurred.

Example

The following example deletes a history value obtained from ListHistoryValuesEx (g_ValueEntryEx). It is also possible to manually input the history value.

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DeleteHistoryValueEx

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Sub VhsDeleteHistoryValueEx()
    Dim VhsDatastoreInterface, req, resp, tag
    Set VhsDatastoreInterface  = CreateObject("CxVhsLib.VhsDatastoreInterface.1")
    Set req = CreateObject("CxVhsLib.DeleteHistoryValueExReq")
    Set resp = CreateObject("CxVhsLib.DeleteHistoryValueExResp")
    Set tag = CreateObject("CxVhsLib.HistoryTagStringEx")
    VhsDatastoreInterface.Open("C:\CygNet\Services\VHS\")
     
    tag.TagString = "CYGDEMO.UIS.00000068:CYG_METER_PDIFF"
    req.TagStringEx = tag
    req.ValueEntryEx = g_ValueEntryEx
    req.Operations = 1
     
    VhsDatastoreInterface.DeleteHistoryValueEx req, resp
     
    'Error handling
    If resp.Error <> 0 Then
        edtMessageBox.Text = "Error number " & resp.Error
    Else
        edtMessageBox.Text = "Completed successfully"
    End If
End Sub

GetNamedArrayValues

The GetNamedArrayValues method reads the history entries from multiple points that were in effect for the given date.

Syntax

GetNamedArrayValues(Request As Variant, Response As Variant) As Integer

Parameters

Parameter	Required	Description	Variant
Request	Yes	The request object that contains the parameters for this method.	GetNamedArrayValuesReq
Response	Yes	The response object that contains the output of this method.	GetNamedArrayValuesResp

Remarks

If no history entries exist at the exact start time, the first history entry prior to the start time will be returned.

Example

The following example displays the history entry data for two points in a list box.

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GetNamedArrayValues

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Sub VhsGetNamedArrayValues()
    Dim VhsDatastoreInterface, req, resp, tag0, tag1
    Set VhsDatastoreInterface  = CreateObject("CxVhsLib.VhsDatastoreInterface.1")
    Set req = CreateObject("CxVhsLib.GetNamedArrayValuesReq")
    Set resp = CreateObject("CxVhsLib.GetNamedArrayValuesResp")
    Set tag0 = CreateObject("CxVhsLib.HistoryTagString")
    Set tag1 = CreateObject("CxVhsLib.HistoryTagString")
    VhsDatastoreInterface.Open("C:\CygNet\Services\VHS\")
     
    req.count = 2
    tag0.TagString = "CYGDEMO.UIS.00000068"
    req.TagString(0) = tag0
    req.TimeStamp(0) = CDate("01/01/2022 15:48:00")
     
    tag1.TagString = "CYGDEMO.UIS.00000069"
    req.TagString(1) = tag1
    req.TimeStamp(1) = CDate("01/01/2022 15:48:00")
     
    VhsDatastoreInterface.GetNamedArrayValues req, resp
     
    If resp.Error <> 0 Then
        edtMessageBox.Text = "Error number " & resp.Error
    Else
    ListBox2.ResetContent
    Dim i
    For i = 0 To resp.count - 1
        ListBox2.AddString("Status - " & resp.entry(i).Status & "; TimeStamp - " & resp.entry(i).Timestamp & "; Value - " & resp.entry(i).Value)
        Next
    End If
End Sub

GetNamedArrayValuesEx

The GetNamedArrayValuesEx method reads the history entries from multiple history points that were in effect for the given date.

Syntax

GetNamedArrayValuesEx(Request As Variant, Response As Variant) As Integer

Parameters

Parameter	Required	Description	Variant
Request	Yes	The request object that contains the parameters for this method.	GetNamedArrayValuesExReq
Response	Yes	The response object that contains the output of this method.	GetNamedArrayValuesExResp

Remarks

If no history entries exist at the exact start time, the first history entry prior to the start time will be returned.

Note: GetNamedArrayValuesExReq objects are limited to 63 total objects within the array. Objects greater than 63 will cause an exception.

Example

The following example displays the history entry data for two points in a list box.

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VhsGetNamedArrayValuesEx

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Sub VhsGetNamedArrayValuesEx()
    Dim VhsDatastoreInterface, req, resp, tag0, tag1
    Set VhsDatastoreInterface  = CreateObject("CxVhsLib.VhsDatastoreInterface.1")
    Set req = CreateObject("CxVhsLib.GetNamedArrayValuesExReq")
    Set resp = CreateObject("CxVhsLib.GetNamedArrayValuesExResp")
    Set tag0 = CreateObject("CxVhsLib.HistoryTagStringEx")
    Set tag1 = CreateObject("CxVhsLib.HistoryTagStringEx")
    VhsDatastoreInterface.Open("C:\CygNet\Services\VHS\")
     
    req.count = 2
    tag0.TagString = "CYGDEMO.UIS.00000068"
    req.TagString(0) = tag0
    req.TimeStamp(0) = CDate("01/01/2022 15:48:00")
     
    tag1.TagString = "CYGDEMO.UIS.00000069"
    req.TagString(1) = tag1
    req.TimeStamp(1) = CDate("01/01/2022 15:48:00")
     
    VhsDatastoreInterface.GetNamedArrayValuesEx req, resp
     
    If resp.Error <> 0 Then
        edtMessageBox.Text = "Error number " & resp.Error
    Else
        edtMessageBox.text = resp.count
        ListBox2.ResetContent
        Dim i
        For i = 0 To resp.Count - 1
        ListBox2.AddString("Status - " & resp.entry(i).Status & "; Userstatus - " & resp.entry(i).UserStatus & "; TimeStamp - " & resp.entry(i).Timestamp & "; Value - " & resp.entry(i).Value)
        Next
    End If
End Sub

GetPointStats

The GetPointStats method gets statistics for a given history point.

Syntax

GetPointStats(Request As Variant, Response As Variant) As Integer

Parameters

Parameter	Required	Description	Variant
Request	Yes	The request object that contains the parameters for this method.	GetPointStatsReq
Response	Yes	The response object that contains the output of this method.	GetPointStatsResp

Remarks

Returns 0 if successful and a non-zero value if an error occurred.

Example

The following example gets statistics for CYGDEMO.UIS.00000068 and displays them in a list box.

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GetPointStats

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Sub VhsGetPointStats()
    Dim VhsDatastoreInterface, req, resp, tag
    Set VhsDatastoreInterface  = CreateObject("CxVhsLib.VhsDatastoreInterface.1")
    Set req = CreateObject("CxVhsLib.GetPointStatsreq")
    Set resp = CreateObject("CxVhsLib.GetPointStatsresp")
    Set tag = CreateObject("CxVhsLib.HistoryTagString")
    bjVhs.Close("C:\CygNet\Services\VHS\")
     
    tag.TagString = "CYGDEMO.UIS.00000068"
    req.TagString = tag
     
    VhsDatastoreInterface.GetPointStats req, resp
     
    If resp.Error <> 0 Then
        edtMessageBox.Text = "Error number " & resp.Error
    Else
        ListBox2.ResetContent
        ListBox2.AddString("Expiration Date: " & resp.ExpirationDays)
        ListBox2.AddString("First History Entry: " & resp.TimeStampStart)
        ListBox2.AddString("Last History Entry: " & resp.TimeStampEnd)
        ListBox2.AddString("Total History Entries: " & resp.Entrycount)
    End If
End Sub

GetPointStatsEx

The GetPointStatsEx method gets statistics for an array of history points.

Syntax

GetPointStatsEx(Request As Variant, Response As Variant) As Integer

Parameters

Parameter	Required	Description	Variant
Request	Yes	The request object that contains the parameters for this method.	GetPointStatsExReq
Response	Yes	The response object that contains the output of this method.	GetPointStatsExResp

Remarks

Returns 0 if successful and a non-zero value if an error occurred.

Example

The following example gets statistics for CYGDEMO.UIS.00000068 and CYGDEMO.UIS.00000069 and displays them in a list box.

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GetPointStatsEx

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Sub VhsGetPointStatsEx()
    Dim VhsDatastoreInterface, req, resp, bRc, tag1, tag2
    Set VhsDatastoreInterface  = CreateObject("CxVhsLib.VhsDatastoreInterface.1")
    Set req = CreateObject("CxVhsLib.GetPointStatsExReq")
    Set resp = CreateObject("CxVhsLib.GetPointStatsExResp")
    Set tag0 = CreateObject("CxVhsLib.HistoryTagStringEx")
    Set tag1 = CreateObject("CxVhsLib.HistoryTagStringEx")
    bRc = VhsDatastoreInterface.Open("C:\CygNet\Services\VHS\")
     
    req.Count = 2
    tag0.TagString = "CYGDEMO.UIS.00000069:CYG_METER_PSTATIC"
    tag1.TagString = "CYGDEMO.UIS.00000068:CYG_METER_PDIFF"
    req.TagString(0) = tag0
    req.TagString(1) = tag1
     
    VhsDatastoreInterface.GetPointStatsEx req, resp
     
    If resp.Error <> 0 Then
        edtMessageBox.Text = "Error number " & resp.Error
    Else
        ListBox2.ResetContent
        Dim i
        For i = 0 To resp.Count - 1
            ListBox2.AddString("Point Number: " & i)
            ListBox2.AddString("Point Error: " & resp.PointError(i))
            ListBox2.AddString("Total History Entries: " & resp.Statistics(i).EntryCount)
            ListBox2.AddString("First History Entry: " & resp.Statistics(i).TimeStampStart)
            ListBox2.AddString("Last History Entry: " & resp.Statistics(i).TimeStampEnd)
            ListBox2.AddString("Expiration Date: " & resp.Statistics(i).ExpirationDays)
            ListBox2.AddString("")
        Next
    End If
End Sub

ListHistoryPointsEx

The ListHistoryPointsEx method lists history points in alphabetic order from the given start index. The ListHistoryPointsEx method has a upper bound array count of 53; the method can only retrieve a maximum of 53 response items per request. The only way to get all points is to iterate through using the last returned item as the new starting point. See the second example below.

Syntax

ListHistoryPointsEx(Request As Variant, Response As Variant) As Integer

Parameters

Parameter	Required	Description	Variant
Request	Yes	The request object that contains the parameters for this method.	ListHistoryPointsExReq
Response	Yes	The response object that contains the output of this method.	ListHistoryPointsExResp

Remarks

Returns 0 if successful and a non-zero value if an error occurred.

Example

The following example gets a list of all history points whose Point ID is greater than 00000123.

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ListHistoryPointsEx

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Sub VhsListHistoryPointsEx()
    Dim VhsDatastoreInterface, req, resp
    Set VhsDatastoreInterface  = CreateObject("CxVhsLib.VhsDatastoreInterface.1")
    Set req = CreateObject("CxVhsLib.ListHistoryPointsExReq")
    Set resp = CreateObject("CxVhsLib.ListHistoryPointsExResp")
    Set tag = CreateObject("CxVhsLib.HistoryTagStringEx")
    VhsDatastoreInterface.Open("C:\CygNet\Services\VHS\")
     
    tag.TagString = "CYGDEMO.UIS.00000123:FREEZIE_METER_VET"
    req.TagString = tag
    VhsDatastoreInterface.ListHistoryPointsEx req, resp
     
    If resp.Error <> 0 Then
        edtMessageBox.Text = "Error number " & resp.Error
    Else
        ListBox2.ResetContent
        Dim i
        For i = 0 To resp.Count - 1
            ListBox2.AddString( i & " - " & resp.Statistics(i).ExpirationDays & " - " & resp.Statistics(i).TimeStampStart & " - " & resp.Statistics(i).TimeStampEnd & " - " & resp.Statistics(i).Entrycount & " - " & resp.TagString(i).TagString)
        Next
    End If
End Sub

The following example iterates through the returned values for ListHistoryPointsEx:

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ListHistoryPointsEx

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' VHS Client Request and Response objects.
 
Dim objVhsDatastoreInterface : Set objVhsDatastoreInterface = CreateObject("CxVHS.VhsDatastoreInterface")
Dim objVHSRequest : Set objVHSRequest = CreateObject("CxVhsLib.ListHistoryPointsExReq")
Dim objVHSResponse : Set objVHSResponse = CreateObject("CxVhsLib.ListHistoryPointsExResp")
Dim objVHSTag : Set objVHSTag = CreateObject("CxVhsLib.HistoryTagStringEx")
 
' Connect the Client to the Service.
Call objVhsDatastoreInterface.Connect("CYGDEMO.VHS")
 
' Prepare the Request
objVHSTag.TagString = "CYGDEMO.UIS.00000000" ' Let's start at "Zero" to try and get everything.
objVHSRequest.TagString = objVHSTag
 
' Send the Initial Request
Call objVhsDatastoreInterface.ListHistoryPointsEx(objVHSRequest, objVHSResponse)
Dim blnFlag : blnFlag = True
 
' Iterate through the response object
Dim intX : intX = 0
Dim intY : intY = 0 ' The UB of the return array
ReDim aryVHSPoints(intX)
 
Dim objFSO : Set objFSO = CreateObject("Scripting.FileSystemObject")
Dim objFile : Set objFile = objFSO.CreateTextFile("C:\temp\ListHistoryPointsEx.txt", True, -2)
 
 
Dim strHeader : strHeader = "******************** ListHistoryValuesEx Results ********************"
Dim strFooter : strFooter = "*********************************************************************"
 
Dim objPoints : Set objPoints = CreateObject("CxScript.Points")
Dim objPoint
 
Call objFile.Write(strHeader & vbCrLf & vbCrLf)
 
Dim blnStop : blnStop = True
 
Do While(intY <= objVHSResponse.TotalPointCount)
 
    For intX = 0 To (objVHSResponse.Count -1)
        ReDim Preserve aryVHSPoints(intY)
        aryVHSPoints(intY) = objVHSResponse.TagString(intX).TagString
        intY = intY + 1
     
    Next
     
    ' Continue the loop till the end...
    On Error Resume next
    Set objPoint = objPoints.Point(aryVHSPoints(intY -1))
    objVHSTag.TagString = objPoint.Tag
    objVHSRequest.TagString = objVHSTag
    Call objVhsDatastoreInterface.ListHistoryPointsEx(objVHSRequest, objVHSResponse)
     
Loop
 
ReDim Preserve aryVHSPoints(intY -1)
intY = 0
 
For Each thing In aryVHSPoints
    Call objFile.Write(intY+1 & " | " & thing & vbCrLf)
    intY = intY + 1
 
Next
 
Call objFile.Write(strFooter)

ListHistoryValuesEx

The ListHistoryValuesEx method reads the history values from a point in chronological order based on the given timestamp. The ListHistoryValuesEx has a upper bound array count of 111; the method can only retrieve a maximum of 111 response items per request. The only way to get all values is to iterate through using the last returned item as the new starting point. See the second example below.

Syntax

ListHistoryValuesEx(Request As Variant, Response As Variant) As Integer

Parameters

Parameter	Required	Description	Variant
Request	Yes	The request object that contains the parameters for this method.	ListHistoryValuesExReq
Response	Yes	The response object that contains the output of this method.	ListHistoryValuesExResp

Remarks

Returns 0 if successful, or return codes: NO_HISTORY_FOR_TIME (12) indicating that there is no history for the time requested or END_OF_HISTORY (10) indicating that there is no more history to retrieve.

We recommend avoiding these message wrappers in favor of the more user-friendly iterators: PointIterator, ValueIterator, and ValueIteratorReverse.

Example

The following example gets all the history values for a point after January 1, 2022 and displays them in a list box. It also stores the first history value in a global variable so it can be used by other methods.

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ListHistoryValuesEx

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Sub VhsListHistoryValuesEx()
    Dim VhsDatastoreInterface, req, resp, tag
    Set VhsDatastoreInterface  = CreateObject("CxVhsLib.VhsDatastoreInterface.1")
    Set req = CreateObject("CxVhsLib.ListHistoryValuesExReq")
    Set resp = CreateObject("CxVhsLib.ListHistoryValuesExResp")
    Set tag = CreateObject("CxVhsLib.HistoryTagStringEx")
    VhsDatastoreInterface.Open("C:\CygNet\Services\VHS\")
     
    tag.TagString = "CYGDEMO.UIS.00000068:CYG_METER_PDIFF"
    Req.TagString = tag
    Req.TimeStampStart = CDate("01/01/2022")
     
    VhsDatastoreInterface.ListHistoryValuesEx req, resp
     
    If resp.Error <> 0 Then
    edtMessageBox.Text = "Error number " & resp.Error
    Else
        Dim i
        ListBox2.ResetContent
        For i = 0 To resp.Count - 1
            ListBox2.AddString(resp.valueEntry(i).Status & " - " & resp.valueEntry(i).UserStatus & " - " & resp.valueEntry(i).TimeStamp & " - " & resp.valueEntry(i).Value)
        Next
         
        'Sets a global variable to the first value entry
        'so it can be used by other methods
        Set g_ValueEntryEx = resp.valueEntry(0) 
    End If
End Sub

The following example iterates through the returned values for ListHistoryValuesEx:

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ListHistoryValuesEx

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Sub VhsListHistoryValuesEx(Byval Cur_Tag, Byval Vhs_Site)
 
    Dim request : Set request = CreateObject("CxVhsLib.ListHistoryValuesExReq")
    Dim response : Set response = CreateObject("CxVhsLib.ListHistoryValuesExResp")
    Dim strHistTag : Set strHistTag = CreateObject("CxVhsLib.HistoryTagStringEx")
     
    Dim strHistoryEntries : strHistoryEntries = ""
    Dim intUnreliable : intUnreliable = 0
     
    VhsDatastoreInterface.Connect(strVHSSite)
     
    strHistTag.TagString = strTag
    request.TagString = strHistTag
    request.TimeStampStart = CDate("1/1/1985")
     
    Dim loop_until
        loop_until = True
         
        Dim X : X = 0
         
        Dim Z : Z = 0
         
        While(loop_until)
         
        Z = 0
         
        VhsDatastoreInterface.ListHistoryValuesEx request, response
         
        Dim i : i = 0
        Dim j : j = 0
         
            Dim timeEntry
            Dim valueEntry
            Dim statusEntry
            Dim historyEntry
            Dim checkEntry
             
            Dim checker
            Dim Rchecker
            Dim results
             
            If(response.Error <> 0 And response.Error <> 10)Then
             
                ' if the response error is 0, there is no error
                ' if the response error is 10, this means "END_OF_HISTORY" -- we're done
             
            Else
             
                For i = 0 To response.Count - 1
             
                    ' What can you do with the results?
                     
                    'objDictionary_Time.SetKeyValue X,response.ValueEntry(i).Value
                    'objDictionary_Value.SetKeyValue X,response.ValueEntry(i).Timestamp
                    'objDictionary_Status.SetKeyValue X,response.ValueEntry(i).Status
                     
                    'timeEntry = objDictionary_Time.FindValue(X)
                    'valueEntry = objDictionary_Value.FindValue(X)
                    'statusEntry = objDictionary_Status.FindValue(X)
                     
                    X = X + 1
                    Z = Z + 1
            Next
         
        End If
         
        If(response.Count = 111)Then
         
            ' Let's start at the last timepoint retrieved and move forward.
            request.TimeStampStart = CDate(response.ValueEntry(Z-1).Timestamp)
         
        Else
            ' Exit
            loop_until = False
         
        End if     
    Wend 
End Sub

Open

The Open method opens a VHS datastore. On an Open() method call, the datastore will be either created or used if it already exists. Only 16 VhsDatastoreInterface objects can be opened at the same time.

Note: The VHS must be shut down to open the datastore. You cannot open a VHS datastore being used by a service that is running.

Syntax

Open(DataDirectory As String, [MaxDatastoreSizeMB as Long = 1024], [TxLogsDirectory As String]) As Boolean

Parameters

Parameter	Required	Description
DataDirectory	Yes	The directory where the VHS data files are located.
MaxDatastoreSizeMB	No	The size to which the VHS datastore can grow in MB. The default value is 1024 MB. The maximum size of a VHS datastore is ~5000000 MB (~5 TB).
TxLogsDirectory	No	The transaction logs directory.

Remarks

Returns True if successful and False if the open failed.

Example

The following example opens to C:\CygNet\Services\VHS\.

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Open

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Sub VhsOpen()
    Dim VhsDatastoreInterface
    Set VhsDatastoreInterface = CreateObject("CxVhsLib.VhsDatastoreInterface")
    VhsDatastoreInterface.Open("C:\CygNet\Services\VHS\")
End Sub

StartHistoryRead

The StartHistoryRead method reads the history entries within an inclusive GMT date range.

Syntax

StartHistoryRead(Request As Variant, Response As Variant) As Integer

Parameters

Parameter	Required	Description	Variant
Request	Yes	The request object that contains the parameters for this method.	StartHistoryReadReq
Response	Yes	The response object that contains the output of this method.	HistoryReadResp

Remarks

Returns 0 if successful and a non-zero value if an error occurred. If no history entries exist at the exact start time, the first history entry prior to the start time will be returned.

Example

The following example reads two history entries between January 1, 2022 and the current date. It then stores Restart in a global variable so that ContinueHistoryRead can read the next set of entries.

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StartHistoryRead

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pasSub VhsStartHistoryRead()
    Dim VhsDatastoreInterface, req, resp, tag
    Set VhsDatastoreInterface  = CreateObject("CxVhsLib.VhsDatastoreInterface.1")
    Set req = CreateObject("CxVhsLib.StartHistoryReadReq")
    Set resp = CreateObject("CxVhsLib.HistoryReadResp")
    Set tag = CreateObject("CxVhsLib.HistoryTagString")
    VhsDatastoreInterface.Open("C:\CygNet\Services\VHS\")
     
    tag.TagString = "CYGDEMO.UIS.00000068"
    req.TagString = tag
    req.Count = 2
    req.TimeStampStart = CDate("01/01/2022")
     
    VhsDatastoreInterface.StartHistoryRead req, resp
     
    If resp.Error <> 0 Then
        edtMessageBox.Text = "Error number " & resp.Error
    Else
        g_restart = resp.Restart
     
        ListBox2.ResetContent
        For i = 0 To resp.Count - 1
            ListBox2.AddString(i & " - " & resp.entry(i).Status & " - " & resp.entry(i).TimeStamp & " - " & resp.entry(i).Value)
        Next  
    End If
End Subte

StartHistoryReadEx

The StartHistoryReadEx method reads the history entries within an inclusive GMT date range.

Syntax

StartHistoryReadEx(Request As Variant, Response As Variant) As Integer

Parameters

Parameter	Required	Description	Variant
Request	Yes	The request object that contains the parameters for this method.	StartHistoryReadExReq
Response	Yes	The response object that contains the output of this method.	HistoryReadExResp

Remarks

This method is capable of returning rollups for the given period. By default, raw values are returned. Returns 0 if successful and a non-zero value if an error occurred. If no history entries exist at the exact start time, the first history entry prior to the start time will be returned.

Example

The following example reads the last value entry from each 30 day period. It then stores Restart in a global variable so that ContinueHistoryReadEx can read the next three entries.

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StartHistoryReadEx

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Sub VhsStartHistoryReadEx()
    Dim VhsDatastoreInterface, req, resp, tag
    Set VhsDatastoreInterface  = CreateObject("CxVhsLib.VhsDatastoreInterface.1")
    Set req = CreateObject("CxVhsLib.StartHistoryReadExReq")
    Set resp = CreateObject("CxVhsLib.HistoryReadExResp")
    Set tag = CreateObject("CxVhsLib.HistoryTagStringEx")
    VhsDatastoreInterface.Open("C:\CygNet\Services\VHS\")
     
    tag.TagString = "CYGDEMO.UIS.00000068:CYG_METER_PDIFF"
    req.TagString = tag
    req.TimeStampStart = "12/03/2022"
    req.TimeStampEnd = Now
    req.RollupType = 9     'Gets the last value entry...
    req.RollupPeriod = 30  '...from each thirty...
    req.RollupUnits = 3    '...day period
    req.Count = 3
     
    VhsDatastoreInterface.StartHistoryReadEx req, resp
     
    If resp.Error <> 0 Then
        edtMessageBox.Text = "Error number " & resp.Error
    Else
        g_restart = resp.Restart
         
        ListBox2.ResetContent
        For i = 0 To resp.Count - 1
            ListBox2.AddString(resp.Entry(i).Status & " - " & resp.entry(i).UserStatus & " - " & resp.entry(i).TimeStamp & " - " & resp.entry(i).Value)
        Next
    End If
End Sub

StoreHistoryList

The StoreHistoryList method stores history entries for multiple history points.

Syntax

StoreHistoryList(Request As Variant, Response As Variant) As Integer

Parameters

Parameter	Required	Description	Variant
Request	Yes	The request object that contains the parameters for this method.	StoreHistoryListReq
Response	Yes	The response object that contains the output of this method.	StoreHistoryListResp

Remarks

The entries do not have to be in chronological order because they will be correctly inserted or appended, however performance is better if they are. Returns 0 if successful and a non-zero value if an error occurred.

Example

The following example stores new value entries for two history points.

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StoreHistoryList

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Sub VhsStoreHistoryList()
    Dim VhsDatastoreInterface, req, resp, entry0, entry1, tag0, tag1
    Set VhsDatastoreInterface  = CreateObject("CxVhsLib.VhsDatastoreInterface.1")
    Set req = CreateObject("CxVhsLib.StoreHistoryListReq")
    Set resp = CreateObject("CxVhsLib.StoreHistoryListResp")
    Set entry0 = CreateObject("CxVhsLib.HistoryEntry")
    Set entry1 = CreateObject("CxVhsLib.HistoryEntry")
    Set tag0 = CreateObject("CxVhsLib.HistoryTagString")
    Set tag1 = CreateObject("CxVhsLib.HistoryTagString")
    VhsDatastoreInterface.Open("C:\CygNet\Services\VHS\")
     
    Req.Count = 2
     
    tag0.TagString = "CYGDEMO.UIS.00000068"
    req.TagString(0) = tag0
    entry0.Status = 7
    entry0.TimeStamp = Now
    entry0.Value = 999
    req.Entry(0) = entry0
     
    tag1.TagString = "CYGDEMO.UIS.00000069"
    req.TagString(1) = tag1
    entry1.Status = 7
    entry1.TimeStamp = Now
    entry1.Value = 123
    Req.Entry(1) = entry1
     
    VhsDatastoreInterface.StoreHistoryList req, resp
     
    If resp.Error <> 0 Then
        edtMessageBox.Text = "Error number " & resp.Error
    Else
        edtMessageBox.Text = "Completed Successfully"
    End If
End Sub

StorePointHistory

The StorePointHistory method stores multiple history entries for a single point.

Syntax

StorePointHistory(Request As Variant, Response As Variant) As Integer

Parameters

Parameter	Required	Description	Variant
Request	Yes	The request object that contains the parameters for this method.	StorePointHistoryReq
Response	Yes	The response object that contains the output of this method.	StorePointHistoryResp

Remarks

Example

The following example stores two history entries for a point. The first entry is inserted at the appropriate time, while the second entry is appended to the history list to be the latest value.

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StorePointHistory

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Sub VhsStorePointHistory()
    Dim VhsDatastoreInterface, req, resp, entry0, entry1, tag
    Set VhsDatastoreInterface  = CreateObject("CxVhsLib.VhsDatastoreInterface.1")
    Set req = CreateObject("CxVhsLib.StorePointHistoryReq")
    Set resp = CreateObject("CxVhsLib.StorePointHistoryResp")
    Set entry0 = CreateObject("CxVhsLib.HistoryEntry")
    Set entry1 = CreateObject("CxVhsLib.HistoryEntry")
    Set tag = CreateObject("CxVhsLib.HistoryTagString")
    VhsDatastoreInterface.Open("C:\CygNet\Services\VHS\")
     
    Req.Count = 2
     
    tag.TagString = "CYGDEMO.UIS.00000068"
    req.TagString = tag
     
    entry0.Status = 7
    entry0.TimeStamp = CDate("01/02/2022")
    entry0.Value = 123
    req.Entry(0) = entry0
     
    entry1.Status = 7
    entry1.TimeStamp = Now
    entry1.Value = 456
    req.Entry(1) = entry1
     
    VhsDatastoreInterface.StorePointHistory req, resp
     
    If resp.Error <> 0 Then
        edtMessageBox.Text = "Error number " & resp.Error
    Else
        edtMessageBox.Text = "Completed Successfully"
    End If
End Sub

StorePointHistoryEx

The StorePointHistoryEx method stores multiple history entries for a single point.

Syntax

StorePointHistory(Request As Variant, Response As Variant) As Integer

Parameters

Parameter	Required	Description	Variant
Request	Yes	The request object that contains the parameters for this method.	StorePointHistoryExReq
Response	Yes	The response object that contains the output of this method.	StorePointHistoryExResp

Remarks

Example

The following example stores two history entries for a point. The first entry is inserted at the appropriate time, while the second entry is appended to the history list to be the latest value.

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StorePointHistoryEx

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Sub VhsStorePointHistoryEx()
    Dim VhsDatastoreInterface, req, resp, entry0, entry1, tag
    Set VhsDatastoreInterface  = CreateObject("CxVhsLib.VhsDatastoreInterface.1")
    Set req = CreateObject("CxVhsLib.StorePointHistoryExReq")
    Set resp = CreateObject("CxVhsLib.StorePointHistoryExResp")
    Set entry0 = CreateObject("CxVhsLib.HistoryEntryEx")
    Set entry1 = CreateObject("CxVhsLib.HistoryEntryEx")
    Set tag = CreateObject("CxVhsLib.HistoryTagStringEx")
    VhsDatastoreInterface.Open("C:\CygNet\Services\VHS\")
     
    req.Count = 2
     
    tag.TagString = "CYGDEMO.UIS.00000068:CYG_METER_PDIFF"
    req.TagString = tag
     
    entry0.Status = 7
    entry0.UserStatus = 0
    entry0.TimeStamp = CDate("01/02/2022")
    entry0.Value = 111
    req.Entry(0) = entry0
     
    entry1.Status = 7
    entry1.UserStatus = 0
    entry1.TimeStamp = Now
    entry1.Value = 222
    req.Entry(1) = entry1
     
    VhsDatastoreInterface.StorePointHistoryEx req, resp
     
    If resp.Error <> 0 Then
        edtMessageBox.Text = "Error number " & resp.Error
    Else
        edtMessageBox.Text = "Completed Successfully"
    End If
End Sub

UpdateHistoryValueEx

The UpdateHistoryValueEx method updates a point’s history value.

Syntax

UpdateHistoryValueEx(Request As Variant, Response As Variant) As Integer

Parameters

Parameter	Required	Description	Variant
Request	Yes	The request object that contains the parameters for this method.	UpdateHistoryValueExReq
Response	Yes	The response object that contains the output of this method.	UpdateHistoryValueExResp

Remarks

Returns 0 if successful and a non-zero value if an error occurred.

Example

The following example adds a new history value to the end of the history list. The value is the current time.

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UpdateHistoryValueEx

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Sub VhsUpdateHistoryValueEx()
    Dim VhsDatastoreInterface, req, resp, history, value, tag
    Set VhsDatastoreInterface  = CreateObject("CxVhsLib.VhsDatastoreInterface.1")
    Set req = CreateObject("CxVhsLib.UpdateHistoryValueExReq")
    Set resp = CreateObject("CxVhsLib.UpdateHistoryValueExResp")
    Set history = CreateObject("CxVhsLib.HistoryEntryEx")
    Set value = CreateObject("CxVhsLib.ValueEntryEx")
    Set tag = CreateObject("CxVhsLib.HistoryTagStringEx")
    VhsDatastoreInterface.Open("C:\CygNet\Services\VHS\")
     
    tag.TagString = "CYGDEMO.UIS.00000068:CYG_METER_PDIFF"
    req.TagStringEx = tag
     
    history.TimeStamp = Now
    history.Value = Time
    req.ValueEntryNew = history
     
    VhsDatastoreInterface.UpdateHistoryValueEx req, resp
     
    If resp.ErrorType <> 0 Then
        edtMessageBox.Text = "Error number " & resp.ErrorType
    Else
        edtMessageBox.Text = "Completed Successfully"
    End If
End Sub