I just checked the screenshot of the OPC server and OPC client which you posted previously.
Your Tag shows as KWh_Tg_akt (but it might be longer as the screenshot only shows a part of it, like .EM.KWh_Tg_akt).
This is the tag that you need to use instead of: Data Type Examples.16 Bit Device.K Registers.FloatArray
So the previous code examples should be modified to look similar to this:
Using Read function:
Private Sub Label3_Click(sender As Object, e As EventArgs) Handles Label3.Click
Dim words() As String
words = OpcDaCom1.Read("KWh_Tg_akt", 1)
Dim A As Single = CSng(words(0))
Dim B As Single = CSng(words(1))
Dim C As Single = CSng(words(3))
Dim D As Single = (A * B * C)
Label3.Text = D
End Sub
Using Subscribe function which will automatically update the values whenever they change:
Private Sub MainForm_Load(sender As Object, e As EventArgs) Handles MyBase.Load
OpcDaCom1.Subscribe("KWh_Tg_akt", 1, 0, AddressOf SubscribedDataChanged)
End Sub
Private Sub SubscribedDataChanged(sender As Object, e As MfgControl.AdvancedHMI.Drivers.Common.PlcComEventArgs)
If e.ErrorId = 0 Then
If e.PlcAddress = "KWh_Tg_akt" Then
Dim D As Single = (e.Values(0) * e.Values(1) * e.Values(3))
Label3.Text = D
End If
End If
End Sub