BOB/DeviceCommand/Base/ModbusTcp.cs

using NModbus;
using System;
using System.Net;
using System.Net.Sockets;
using System.Threading;
using System.Threading.Tasks;

namespace DeviceCommand.Base
{
    public class ModbusTcp
    {
        public string IPAddress { get; private set; } = "127.0.0.1";
        public int Port { get; private set; } = 502;
        public int SendTimeout { get; private set; } = 3000;
        public int ReceiveTimeout { get; private set; } = 3000;
        public TcpClient TcpClient { get; private set; } = new TcpClient();
        public IModbusMaster Modbus { get; private set; }

        private readonly SemaphoreSlim _commLock = new(1, 1);

        public void ConfigureDevice(string ipAddress, int port, int sendTimeout = 3000, int receiveTimeout = 3000)
        {
            IPAddress = ipAddress;
            Port = port;
            SendTimeout = sendTimeout;
            ReceiveTimeout = receiveTimeout;
        }

        public async Task<bool> ConnectAsync(CancellationToken ct = default)
        {
            await _commLock.WaitAsync(ct);
            try
            {
                if (TcpClient.Connected)
                {
                    var remoteEndPoint = (IPEndPoint)TcpClient.Client.RemoteEndPoint!;
                    if (remoteEndPoint.Address.MapToIPv4().ToString() == IPAddress && remoteEndPoint.Port == Port)
                        return true;

                    TcpClient.Close();
                    TcpClient.Dispose();
                    TcpClient = new TcpClient();
                }

                await TcpClient.ConnectAsync(IPAddress, Port, ct);
                Modbus = new ModbusFactory().CreateMaster(TcpClient);
                return true;
            }
            finally
            {
                _commLock.Release();
            }
        }
        public void Close()
        {
            if (TcpClient.Connected) TcpClient.Close();
        }

        public async Task WriteSingleRegisterAsync(byte slaveAddress, ushort registerAddress, ushort value, CancellationToken ct = default)
        {
            await _commLock.WaitAsync(ct);
            try
            {
                await Modbus.WriteSingleRegisterAsync(slaveAddress, registerAddress, value).WaitAsync(TimeSpan.FromMinutes(SendTimeout),ct);
            }
            finally
            {
                _commLock.Release();
            }
        }

        public async Task WriteMultipleRegistersAsync(byte slaveAddress, ushort startAddress, ushort[] values, CancellationToken ct = default)
        {
            await _commLock.WaitAsync(ct);
            try
            {
                await Modbus.WriteMultipleRegistersAsync(slaveAddress, startAddress, values).WaitAsync(TimeSpan.FromMinutes(SendTimeout), ct);
            }
            finally
            {
                _commLock.Release();
            }
        }

        public async Task<ushort[]> ReadHoldingRegistersAsync(byte slaveAddress, ushort startAddress, ushort numberOfPoints, CancellationToken ct = default)
        {
            await _commLock.WaitAsync(ct);
            try
            {
                var result =await Modbus.ReadHoldingRegistersAsync(slaveAddress, startAddress, numberOfPoints).WaitAsync(TimeSpan.FromMinutes(SendTimeout), ct);
                return result;
            }
            finally
            {
                _commLock.Release();
            }
        }

        public async Task WriteSingleCoilAsync(byte slaveAddress, ushort coilAddress, bool value, CancellationToken ct = default)
        {
            await _commLock.WaitAsync(ct);
            try
            {
                await Modbus.WriteSingleCoilAsync(slaveAddress, coilAddress, value).WaitAsync(TimeSpan.FromMinutes(SendTimeout), ct);
            }
            finally
            {
                _commLock.Release();
            }
        }

        public async Task<bool[]> ReadCoilsAsync(byte slaveAddress, ushort startAddress, ushort numberOfPoints, CancellationToken ct = default)
        {
            await _commLock.WaitAsync(ct); 
            try
            {
                var result = await Modbus.ReadCoilsAsync(slaveAddress, startAddress, numberOfPoints).WaitAsync(TimeSpan.FromMinutes(SendTimeout), ct);
                return result;
            }
            finally
            {
                _commLock.Release();
            }
        }

        public async Task<ushort[]> ReadInputRegistersAsync(byte slaveAddress, ushort startAddress, ushort numberOfPoints, CancellationToken ct = default)
        {
            await _commLock.WaitAsync(ct);
            try
            {
                var result = await Modbus.ReadInputRegistersAsync(slaveAddress, startAddress, numberOfPoints).WaitAsync(TimeSpan.FromMinutes(SendTimeout), ct);
                return result;
            }
            finally
            {
                _commLock.Release();
            }
        }
    }
}