using System;
using Hylasoft.Opc.Da;
 
namespace TestWrite_H_OPC
{
    class Program
    {
        static void Main(string[] args)
        {
            using (var client = new DaClient(new Uri("opcda://127.0.0.1/Kepware.KEPServerEX.V6")))
            {
                client.Connect();
                var tag = "Simulation Examples.Functions.Write1";
                client.Write(tag, 150); // Write Value
                var val = client.Read<o-bject>(tag).Value; // Read Value
                Console.WriteLine(val);
            }
        }
    }
}

using OpcLabs.EasyOpc.DataAccess;
using OpcLabs.EasyOpc.OperationModel;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
 
namespace TestWrite
{
    class Program
    {
        static void Main(string[] args)
        {
            var client = new EasyDAClient();
            try
            {
                client.WriteItemValue("", "Kepware.KEPServerEX.V6", "Simulation Examples.Functions.Write1", "10");
            }
            catch(OpcException e)
            {
                Console.WriteLine("OPC Exception was thrown");
            }
            catch(Exception e)
            {
                Console.WriteLine("Unhandled Exception was thrown");
            }
        }
    }
}