EMOS-TestApp/TestApp/Program.cs

using NModbus;
using System.Net.Sockets;

namespace TestApp
{
    internal class Program
    {
        static void Main(string[] args)
        {
            while (true)
            {
                try
                {
                    ConnectToModBus();
                }
                catch (Exception ex)
                {
                    Console.WriteLine($"Error connecting to ModBus slave: {ex.Message}");
                    Thread.Sleep(5000);
                }
            }
        }

        private static void ConnectToModBus()
        {
            var factory = new ModbusFactory();
            var tcpClient = new TcpClient("192.168.188.21", 502);
            var master = factory.CreateMaster(tcpClient);
            Console.WriteLine("ModBus TCP Connection established!");

            while (tcpClient.Connected)
            {
                try
                {
                    ushort input = master.ReadHoldingRegisters(1, 1000, 1)[0];
                    ushort output = (ushort)(input + 50);
                    master.WriteMultipleRegisters(1, 1100, new ushort[] { output });
                    Console.WriteLine($"Register values updated to {input} + 50 = {output}");
                    Thread.Sleep(100);
                }
                catch (Exception e)
                {
                    Console.WriteLine($"Error updating ModBus registers: {e.Message}");
                    Thread.Sleep(1000);
                }
            }
        }

    }
}