DataChange event

Description
The DataChange event is called when the item value or quality changes
Syntax
DataChange
(TransactionID As Long, NumItems As Long, ClientHandles() As Long, ItemValues() As Variant, Qualities() As Long, TimeStamps() As Date)
TransactionID
— The client specified transaction ID. A non-0 value for this indicates that this call has been generated as a result of an AsyncRefresh. A value of 0 indicates that this call has been generated as a result of the normal subscription processing.
NumItems
— Number of items returned.
ClientHandles
— Array of client handles for the items.
ItemValues
— Array of values.
Qualities
— Array of Qualities for each item's value.
TimeStamps
— Array of UTC TimeStamps for each item's value. If the device cannot provide a timestamp, the server will provide one.
Remarks
If the item values are changing faster than the update rate, only the most recent value for each item will be returned to the client.
Example
Dim WithEvents AnOPCGroup As OPCGroup
Private Sub AnOPCGroup_DataChange (TransactionID As Long, NumItems As Long, ClientHandles() As Long, ItemValues() As Variant, Qualities() As Long, TimeStamps() As Date)
' write your client code here to process the data change values
End Sub
Dim i As Long
'/* Update display with new data
For i = 1 To NumItems
'/* Update value
txtData(ClientHandles(i)) = ItemValues(i)
'/* Update Quality field
txtQuality(ClientHandles(i)) = Qualities(i)
'/* Update timestamp
txtTimeStamp(ClientHandles(i)) = TimeStamp(i)
Next 'i
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