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Retrieving modbus frame

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Thomas
2022-03-05
2022-03-10

  • Thomas

    Thomas - 2022-03-05

    Hello,
    Is there any way to get a full modbus frame (RTU) received from slave? I can't find any solution in codesamples or in the forum.
    Anyone can share their code?
    Thanks a lot.

     

  • Thomas

    Thomas - 2022-03-06

    Good morning,

    I am looking for a solution to get full modbus package (not just a value received from the remote device). The best would be to store each byte from the package in the array.
    For now I found a C code in SRE EasyModbusAdvancedClient and converted to the VB.net.

    Seems sendData and receiveData are the arrays w with Modbus packages, but I can't get the value of the specific index.
    For now I change the package to string (as in original code) and use Substring to get exact "byte", but this is not a nice solution:

    Dim s As String = BitConverter.ToString(modbusClient.sendData).Substring(3, 2)
    txtByte.Text = s

    Any better ideas?

     modbusClient = New ModbusClient(cboCOMPort.Text)
 AddHandler modbusClient.ReceiveDataChanged, New EasyModbus.ModbusClient.ReceiveDataChangedHandler(AddressOf UpdateReceiveData)
AddHandler modbusClient.SendDataChanged, New EasyModbus.ModbusClient.SendDataChangedHandler(AddressOf UpdateSendData)

            Delegate Sub UpdateReceiveDataCallback()

    Private Sub UpdateReceiveData(ByVal sender As [Object])
        receiveData = "Rx: " & BitConverter.ToString(modbusClient.receiveData).Replace("-", " ") & System.Environment.NewLine
        Dim thread As New Thread(AddressOf updateReceiveTextBox)
        thread.Start()
    End Sub

    Private Sub updateReceiveTextBox()
        If TextBox1.InvokeRequired Then
            Dim d As New UpdateReceiveDataCallback(AddressOf updateReceiveTextBox)
            Me.Invoke(d, New [Object]() {})
        Else
            TextBox1.AppendText(receiveData)
        End If
    End Sub


    Private Sub UpdateSendData(ByVal sender As [Object])
        'sendData = "Tx: " & BitConverter.ToString(modbusClient.sendData).Replace("-", " ") & System.Environment.NewLine
        sendData = BitConverter.ToString(modbusClient.sendData)
        Dim thread As New Thread(AddressOf updateSendTextBox)
        thread.Start()

    End Sub

    Private Sub updateSendTextBox()
        If TextBox1.InvokeRequired Then
            Dim d As New UpdateReceiveDataCallback(AddressOf updateSendTextBox)
            Me.Invoke(d, New [Object]() {})
        Else
            TextBox1.AppendText(sendData)
        End If
    End Sub
     

    • Nikoloz Qvrivishvili

      Nikoloz Qvrivishvili - 2022-03-10

      Good morning!

      Please have a look at:  https://control.com/forums/threads/homebrewed-software-to-communicate-with-measuring-device-via-modbus-tcp.49152/page-2

      The matters you’re interrogating right over there.
      N. Qv.

      Воскресенье, 6 марта 2022, 13:58 +04:00 от Thomas ztomaj@users.sourceforge.net:

      Good morning,
      I am looking for a solution to get full modbus package (not just a value received from the remote device). The best would be to store each byte from the package in the array.
      For now I found a C code in SRE EasyModbusAdvancedClient and converted to the VB.net.
      Seems sendData and receiveData are the arrays w with Modbus packages, but I can't get the value of the specific index.
      For now I change the package to string (as in original code) and use Substring to get exact "byte", but this is not a nice solution:
      Dim s As String = BitConverter.ToString(modbusClient.sendData).Substring(3, 2)
      txtByte.Text = s
      Any better ideas?
      modbusClient = New ModbusClient(cboCOMPort.Text)
      AddHandler modbusClient.ReceiveDataChanged, New EasyModbus.ModbusClient.ReceiveDataChangedHandler(AddressOf UpdateReceiveData)
      AddHandler modbusClient.SendDataChanged, New EasyModbus.ModbusClient.SendDataChangedHandler(AddressOf UpdateSendData)

             Delegate Sub UpdateReceiveDataCallback()

      Private Sub UpdateReceiveData(ByVal sender As [Object])
      receiveData = "Rx: " & BitConverter.ToString(modbusClient.receiveData).Replace("-", " ") & System.Environment.NewLine
      Dim thread As New Thread(AddressOf updateReceiveTextBox)
      thread.Start()
      End Sub

      Private Sub updateReceiveTextBox()
      If TextBox1.InvokeRequired Then
      Dim d As New UpdateReceiveDataCallback(AddressOf updateReceiveTextBox)
      Me.Invoke(d, New Object {})
      Else
      TextBox1.AppendText(receiveData)
      End If
      End Sub

      Private Sub UpdateSendData(ByVal sender As [Object])
      'sendData = "Tx: " & BitConverter.ToString(modbusClient.sendData).Replace("-", " ") & System.Environment.NewLine
      sendData = BitConverter.ToString(modbusClient.sendData)
      Dim thread As New Thread(AddressOf updateSendTextBox)
      thread.Start()

      End Sub

      Private Sub updateSendTextBox()
      If TextBox1.InvokeRequired Then
      Dim d As New UpdateReceiveDataCallback(AddressOf updateSendTextBox)
      Me.Invoke(d, New Object {})
      Else
      TextBox1.AppendText(sendData)
      End If
      End Sub

      Retrieving modbus frame

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      --
      Николоз Квривишвили
      Отправлено из Почты Mail.ru

       
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