ADP/DeviceCommand/Base/ModbusRtu.cs

using NModbus;
using NModbus.Serial;
using System;
using System.IO.Ports;
using System.Threading;
using System.Threading.Tasks;

namespace DeviceCommand.Base
{
    public class ModbusRtu : IModbusDevice
    {
        public string PortName { get; private set; } = "COM1";
        public int BaudRate { get; private set; } = 9600;
        public int DataBits { get; private set; } = 8;
        public StopBits StopBits { get; private set; } = StopBits.One;
        public Parity Parity { get; private set; } = Parity.None;
        public int ReadTimeout { get; private set; } = 3000;
        public int WriteTimeout { get; private set; } = 3000;

        private SerialPort _serialPort;
        public IModbusMaster Modbus { get; private set; }
        public bool IsConnected => _serialPort?.IsOpen ?? false;

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

        public ModbusRtu()
        {
            _serialPort = new SerialPort();
        }

        public void ConfigureDevice(string portName, int baudRate, int dataBits = 8, StopBits stopBits = StopBits.One, Parity parity = Parity.None, int readTimeout = 3000, int writeTimeout = 3000)
        {
            PortName = portName;
            BaudRate = baudRate;
            DataBits = dataBits;
            StopBits = stopBits;
            Parity = parity;
            ReadTimeout = readTimeout;
            WriteTimeout = writeTimeout;
        }

        public virtual async Task<bool> ConnectAsync(CancellationToken ct = default)
        {
            await _commLock.WaitAsync(ct);
            try
            {
                if (_serialPort.IsOpen)
                    _serialPort.Close();

                _serialPort.PortName = PortName;
                _serialPort.BaudRate = BaudRate;
                _serialPort.DataBits = DataBits;
                _serialPort.StopBits = StopBits;
                _serialPort.Parity = Parity;
                _serialPort.ReadTimeout = ReadTimeout;
                _serialPort.WriteTimeout = WriteTimeout;
                _serialPort.Open();

                Modbus = new ModbusFactory().CreateRtuMaster(_serialPort);
                return true;
            }
            finally
            {
                _commLock.Release();
            }
        }

        public virtual void Close()
        {
            if (_serialPort.IsOpen)
                _serialPort.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.FromMilliseconds(WriteTimeout), 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.FromMilliseconds(WriteTimeout), ct);
            }
            finally
            {
                _commLock.Release();
            }
        }

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

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

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

        public void Dispose()
        {
            _serialPort?.Dispose();
            _commLock?.Dispose();
        }
    }
}