使用c#编写的Modbus TCP通讯软件示例：

下面是一个使用C#编写的Modbus TCP通讯软件示例：

using System;
using System.Net.Sockets;

// Modbus TCP帧结构
class ModbusTCPFrame
{
    public ushort TransactionId { get; set; }
    public ushort ProtocolId { get; set; }
    public ushort Length { get; set; }
    public byte UnitId { get; set; }
    public byte FunctionCode { get; set; }
    public byte[] Data { get; set; }

    // 将Modbus TCP帧转换为字节数组
    public byte[] ToBytes()
    {
        byte[] buffer = new byte[12 + Data.Length];
        BitConverter.GetBytes(TransactionId).CopyTo(buffer, 0);
        BitConverter.GetBytes(ProtocolId).CopyTo(buffer, 2);
        BitConverter.GetBytes(Length).CopyTo(buffer, 4);
        buffer[6] = UnitId;
        buffer[7] = FunctionCode;
        Data.CopyTo(buffer, 8);
        return buffer;
    }

    // 从字节数组解析Modbus TCP帧
    public static ModbusTCPFrame FromBytes(byte[] buffer)
    {
        ModbusTCPFrame frame = new ModbusTCPFrame();
        frame.TransactionId = BitConverter.ToUInt16(buffer, 0);
        frame.ProtocolId = BitConverter.ToUInt16(buffer, 2);
        frame.Length = BitConverter.ToUInt16(buffer, 4);
        frame.UnitId = buffer[6];
        frame.FunctionCode = buffer[7];
        frame.Data = new byte[frame.Length - 1];
        Array.Copy(buffer, 8, frame.Data, 0, frame.Length - 1);
        return frame;
    }
}

// Modbus TCP客户端
class ModbusTCPClient
{
    private TcpClient client;
    private NetworkStream stream;
    private byte unitId;

    public ModbusTCPClient(string host, int port, byte unitId)
    {
        client = new TcpClient(host, port);
        stream = client.GetStream();
        this.unitId = unitId;
    }

    // 发送Modbus TCP请求并接收响应
    private byte[] SendRequest(byte functionCode, byte[] data)
    {
        ModbusTCPFrame frame = new ModbusTCPFrame();
        frame.TransactionId = 0;
        frame.ProtocolId = 0;
        frame.Length = (ushort)(data.Length + 1);
        frame.UnitId = unitId;
        frame.FunctionCode = functionCode;
        frame.Data = data;
        byte[] buffer = frame.ToBytes();
        stream.Write(buffer, 0, buffer.Length);
        buffer = new byte[1024];
        int count = stream.Read(buffer, 0, buffer.Length);
        Array.Resize(ref buffer, count);
        frame = ModbusTCPFrame.FromBytes(buffer);
        return frame.Data;
    }

    // 读取线圈状态
    public bool[] ReadCoils(ushort address, ushort count)
    {
        byte[] data = new byte[4];
        BitConverter.GetBytes(address).CopyTo(data, 0);
        BitConverter.GetBytes(count).CopyTo(data, 2);
        byte[] response_data = SendRequest(0x01, data);
        bool[] coils = new bool[count];
        for (int i = 0; i < count; i++)
        {
            coils[i] = (response_data[i / 8] & (1 << (i % 8))) != 0;
        }
        return coils;
    }

    // 写入单个线圈状态
    public void WriteCoil(ushort address, bool value)
    {
        byte[] data = new byte[4];
        BitConverter.GetBytes(address).CopyTo(data, 0);
        BitConverter.GetBytes(value ? (ushort)0xFF00 : (ushort)0x0000).CopyTo(data, 2);
        SendRequest(0x05, data);
    }

    // 读取保持寄存器
    public ushort[] ReadHoldingRegisters(ushort address, ushort count)
    {
        byte[] data = new byte[4];
        BitConverter.GetBytes(address).CopyTo(data, 0);
        BitConverter.GetBytes(count).CopyTo(data, 2);
        byte[] response_data = SendRequest(0x03, data);
        ushort[] registers = new ushort[count];
        for (int i = 0; i < count; i++)
        {
            registers[i] = BitConverter.ToUInt16(response_data, i * 2);
        }
        return registers;
    }

    // 写入单个保持寄存器
    public void WriteHoldingRegister(ushort address, ushort value)
    {
        byte[] data = new byte[4];
        BitConverter.GetBytes(address).CopyTo(data, 0);
        BitConverter.GetBytes(value).CopyTo(data, 2);
        SendRequest(0x06, data);
    }

    // 关闭连接
    public void Close()
    {
        stream.Close();
        client.Close();
    }
}

使用该Modbus TCP客户端可以进行读写线圈状态和保持寄存器的操作。例如，读取保持寄存器可以使用以下代码：

ModbusTCPClient client = new ModbusTCPClient("192.168.1.10", 502, 1);
ushort[] registers = client.ReadHoldingRegisters(0x0000, 8);
client.Close();
foreach (ushort register in registers)
{
    Console.WriteLine(register);
}

其中，`192.168.1.10`是Modbus TCP从设备的IP地址，`502`是Modbus TCP从设备的端口号，`1`是Modbus TCP从设备的设备地址，`0x0000`是保持寄存器地址，`8`是读取的保持寄存器数量。