Reproducing the Client code

[Ganesh Gebhard]

I'm trying to reproduce the client example code, but I get an error everytime I try that. However, the code of your project and my project are exactly the same. Yours is modified in such a way that it only has to connect. So the user clicks a button, the IP and Port are used to connect and a label shows if its connected or not.

Your code (modified)

/*
 * Created by SharpDevelop.
 * User: www.rossmann-engineering.de
 * To change this template use Tools | Options | Coding | Edit Standard Headers.
 */
using System;
using System.Collections.Generic;
using System.Drawing;
using System.Windows.Forms;

namespace EasyModbusClientExample
{
    /// <summary>
    /// Description of MainForm.
    /// </summary>
    public partial class MainForm : Form
    {
        private EasyModbus.ModbusClient modbusClient;

        public MainForm()
        {
            InitializeComponent();
            modbusClient = new EasyModbus.ModbusClient();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            try
            {
                if (!modbusClient.Connected)
                {
                    modbusClient.IPAddress = txtIpAddressInput.Text;
                    modbusClient.Port = int.Parse(txtPortInput.Text);
                    modbusClient.Connect();

                    label1.Text = "Connected";
                }
            }
            catch (Exception exc)
            {
                MessageBox.Show(exc.Message, "Exception Reading values from Server", MessageBoxButtons.OK, MessageBoxIcon.Error);
            }
        }
    }
}

My code:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace WindowsFormsApp1
{
    public partial class Form1 : Form
    {
        private EasyModbus.ModbusClient modbusClient;

        public Form1()
        {
            InitializeComponent();
            modbusClient = new EasyModbus.ModbusClient();
        }

        private void button1_Click(object sender, EventArgs e)
        {

                if (!modbusClient.Connected)
                {
                    modbusClient.IPAddress = txtIpAddressInput.Text;
                    modbusClient.Port = int.Parse(txtPortInput.Text);
                    modbusClient.Connect();

                    label1.Text = "Connected";
                }

        }
    }
}

The error is: No connection could be made because the target machine actively refused it.
In: System.Net.Sockets.SocketException occurred
File 'ModbusClient.cs', line 106.

Am I missing something?

I hope you can help me.

[Rossmann Engineering]

Hi, the settings for P-Address and Port of the Modbus Server is correct, and the settings of your Network-Adapter is correct? Yout Firewall allows connection?

Did you try to connect using my Modbus-Client example?

[Anonymous]

[Ganesh Gebhard]

Yep, your version works. So everything from my side is configured correctly. Only when I want to reproduce the example I get the error.

[Rossmann Engineering]

Okay, I think I see. Please Modify:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace WindowsFormsApp1
{
public partial class Form1 : Form
{
private EasyModbus.ModbusClient modbusClient;

    public Form1()
    {
        InitializeComponent();
        modbusClient = new EasyModbus.ModbusClient(txtIpAddressInput.Text, txtPortInput.Text);
    }

    private void button1_Click(object sender, EventArgs e)
    {

            if (!modbusClient.Connected)
            {

                modbusClient.Connect();

                label1.Text = "Connected";
            }

    }
}

}

The library supports different Modbus Versions. If you are trying to get the "Connected" Property before you selected to use ModbusTCP (By using the correct constructor or by colling the Connect Method at leasst once) you'll always get TRUE.

[Rossmann Engineering]

Forgot to mention, you could update the Port and IPAddress by using the Properties in the same way you already did.

            if (!modbusClient.Connected)
            {
                modbusClient.IPAddress = txtIpAddressInput.Text;
                modbusClient.Port = int.Parse(txtPortInput.Text);
                modbusClient.Connect();

                label1.Text = "Connected";
            }

[Ganesh Gebhard]

It works! Thanks! :)