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  Web Based Applications using the OPC Web Client Web Service
Quick links within this page
Objective
Reading a Single Tag
 ASP.NET
Try
'create the opc web client web-service object
Dim objOWC As New OPCLabs.EasyOPCDANet.EasyDAWS
'create a vtq object to receive the tag read
'and make the call to read the tag
Dim objVTQ As OPCLabs.EasyOPCDANet.IVTQNet = objOWC.ReadItem _
( _
"", _
"OPCLabs.KitServer.2", _
"Simulation.Random" _
)
'display the output to the browser
If Not objVTQ Is Nothing Then
Response.Write("<p>Value: " & objVTQ.Value & "</p>")
Response.Write("<p>Quality: " & objVTQ.Quality & "</p>")
Response.Write("<p>Timestamp: " & objVTQ.Timestamp & "</p>")
End If
Catch ex As Exception
'display exceptions to the browser
Response.Write("Error: " & ex.Message)
If Not ex.InnerException Is Nothing Then
Response.Write("Inner Err: " & ex.InnerException.Message)
End If
End Try
Reading Multiple Tags within a single Transaction
ASP.NET
Try
'create an opc web client object
Dim EasyDA As New OPCLabs.EasyOPCDANet.EasyDAWS
'create an array to receive the item read results
Dim VTQs As System.Array
'make the call to read the items
VTQs = EasyDA.ReadMultipleItems _
( _
"", _
"OPCLabs.KitServer.2", _
New String() _
{ _
"Simulation.Random", _
"Trends.Ramp (1 min)", _
"Trends.Sine (1 min)", _
"Simulation.Register_I4" _
} _
)
'now to see what we received
If Not VTQs Is Nothing Then
'iterate thru the dictionary
For Each item As OPCLabs.EasyOPCDANet.IVTQNet In VTQs
'write the values to the browser
Response.Write(item.Value _
& " (" & item.Quality & ")" _
& " @ " & item.Timestamp _
& "<br>")
Next
End If
Catch ex As Exception
'send exception details to screen
Response.Write("Err: " & ex.Message)
End Try
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