Register Addresses above 4096

Daniel J Palmer — Mon, 16 Jun 2025 11:33:43 -0000

Hello, I am using the demo project and I am getting errors reading any registers above 4095.
I know the variables in the program can handle the higher numbers, but the program crashes when I try 4096 or above. I assume I am doing something wrong, but not sure what. Any help is appreciated.
Thanks !

How to read over 120 coils (2000 max)?

Edward Castillo — Mon, 16 Dec 2024 23:02:45 -0000

Hi all I'm running into an error when I try to read over 120 coils. The first 120 read fine but for some reason cannot read over 120. This code is inside a polling timer:

The error highlights the input 121 line of code then i get:
System.IndexOutOfRangeException: 'Index was outside the bounds of the array.'

ModbusClient PLC = new ModbusClient(plcIP, 502);
PLC.Connect();

bool[] inputs = PortalPLC.ReadCoils(0, 20);
bool[] inputs2 = PortalPLC.ReadCoils(120, 20);

//==========input18 FEEDBACK===========================================
if (inputs[18] == true)
{
//update indicator
}
else if (inputs[18] == false)
{
//update indicator
}
//=======input 121 FEEDBACK=============================================
if (inputs2[121] == true)
{
//update indicator
}
else if (inputs2[121] == false)
{
//update indicator
}

how to read floating registers

Stanley Michel Polanco Recarey — Mon, 17 Jun 2024 20:46:57 -0000

Greetings dear, I am trying to read a floating record and I can't.

I have only been able to write using the following code: modbus.WriteMultipleRegisters(1060,ModbusClient.ConvertFloatToRegisters(float,ModbusClient.RegisterOrder.LowHigh));

EasyModbusTCP.NET 5.0 - IOExceptions

Scott Mongrain — Sun, 24 Apr 2022 16:24:28 -0000

Yes. Connections (and thus, clients) are cheap; abandon them at the earliest sign of trouble. That means using Try...Catch where you should toss the connection in the Catch block as basically the only action (don't try to resolve anything, it's useless and more effort than it's worth), abandoning it after any latency longer than you'd like, also after a malformed response, etc. Basically just constantly remake clients/connections (they're more or less one and the same) and everything works perfectly. From there you can assess what things you'd actually like to try to accommodate/fix, but start with just tossing everything at the slightest sign of trouble and you'll be encouraged by how well the results bear out. I know I was!

You can see the full program here.

EasyModbusTCP.NET 5.0 - IOExceptions

abx qwq — Tue, 19 Apr 2022 09:06:54 -0000

Hi Scott, I have the same issue. Did you resolve this ?

Retrieving modbus frame

Thomas — Sun, 06 Mar 2022 09:58:30 -0000

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

Tomasz Zieliński — Sat, 05 Mar 2022 11:16:50 -0000

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.

EasyModbus Java TCP Client, obtain the registration number.

Americo Bravo Astrona — Sat, 26 Feb 2022 15:42:21 -0000

Dear community, I am learning to use EasyModbus and I am starting with an example that I found in your web page, however reviewing the documentation I could not find an option that allows me to print the register address that I am reading, for example I want to save in a database the following information:

Registration Address, Registration Value.

Does anyone know how to get this value?

Maybe my question is too basic?

thank you for your kind attention.

Java - Modbus client Read 32-bit float.

Hans H — Thu, 30 Dec 2021 22:55:36 -0000

I cannot find any example where I can read a 32-bit float register with or without transformation between hex and decimal.

Java Modbus client with several modbus units

Hans H — Thu, 30 Dec 2021 22:51:33 -0000

I cannot find any Java client example where I can connect to a Modbus server with several Modbus units (different Modbus ID's)?

Recent posts to General Discussion

Register Addresses above 4096

How to read over 120 coils (2000 max)?

how to read floating registers

EasyModbusTCP.NET 5.0 - IOExceptions

EasyModbusTCP.NET 5.0 - IOExceptions

Retrieving modbus frame

Retrieving modbus frame

EasyModbus Java TCP Client, obtain the registration number.

Java - Modbus client Read 32-bit float.

Java Modbus client with several modbus units