C# WPF 使用libmodbus库实现Modbus协议
主要功能点：
1 读取线圈寄存器
2 读保持寄存器
3 写线圈寄存器
4 写保持寄存器
更多方法请参考下面代码的方法，还有一些没有使用
如果需要IP地址进行连接也可以

这是效果图，在调用之前需要在libmodbus官网下载类库后调用方法即可`

	 //RTU模式创建的关联函数
    [DllImport("modbus.dll", EntryPoint = "modbus_new_rtu",
    CharSet = CharSet.Ansi)]
    public static extern IntPtr modbus_new_rtu(string device, int baud,
    char parity, int data_bit, int stop_bit);
    //TCP模式创建的关联函数
    [DllImport("modbus.dll", EntryPoint = "modbus_new_tcp",
    CharSet = CharSet.Ansi)]
    public static extern IntPtr modbus_new_tcp(string ip_address, int port);
    //共通的操作函数
    [DllImport("modbus.dll", EntryPoint = "modbus_set_slave",
    CharSet = CharSet.Ansi)]
    public static extern int modbus_set_slave(IntPtr ctx,int slave);
    [DllImport("modbus.dll", EntryPoint = "modbus_connect",
    CharSet = CharSet.Ansi)]
    public static extern int modbus_connect(IntPtr ctx);

    [DllImport("modbus.dll", EntryPoint = "modbus_read_bits",
    CharSet = CharSet.Ansi)]
    public static extern int modbus_read_bits(IntPtr ctx, int addr,
    int nb, byte[] dest);
    [DllImport("modbus.dll", EntryPoint = "modbus_read_input_bits",
        CharSet = CharSet.Ansi)]
    public static extern int modbus_read_input_bits(IntPtr ctx,
    int addr, int nb, byte[] dest);
    [DllImport("modbus.dll", EntryPoint = "modbus_read_registers",
    CharSet = CharSet.Ansi)]
    public static extern int modbus_read_registers(IntPtr ctx,
    int addr, int nb, UInt16[] dest);
    [DllImport("modbus.dll", EntryPoint = "modbus_read_input_registers",
    CharSet = CharSet.Ansi)]
    public static extern int modbus_read__input_registers(IntPtr ctx,
    int addr, int nb, UInt16[] dest);

    [DllImport("modbus.dll", EntryPoint = "modbus_write_bit",
    CharSet = CharSet.Ansi)]
    public static extern int modbus_write_bit(IntPtr ctx,
    int coil_addr, int status);

    [DllImport("modbus.dll", EntryPoint = "modbus_write_register",
    CharSet = CharSet.Ansi)]
    public static extern int modbus_write_register(IntPtr ctx,
    int reg_addr, int value);

    [DllImport("modbus.dll", EntryPoint = "modbus_write_bits",
    CharSet = CharSet.Ansi)]
    public static extern int modbus_write_bits(IntPtr ctx,
    int coil_addr, int nb, byte[] status);

    [DllImport("modbus.dll", EntryPoint = "modbus_write_registers",
    CharSet = CharSet.Ansi)]
    public static extern int modbus_write_registers(IntPtr ctx,
    int reg_addr, int nb, UInt16[] status);
    [DllImport("modbus.dll", EntryPoint = "modbus_write_and_read_registers",
    CharSet = CharSet.Ansi)]
    public static extern int modbus_write_and_read_registers(IntPtr ctx,int write_addr, int write_nb, UInt16[] src,int read_addr, int read_nb, UInt16[] dest);
    [DllImport("modbus.dll", EntryPoint = "modbus_close",
    CharSet = CharSet.Ansi)]
    public static extern void modbus_close(IntPtr ctx);
    [DllImport("modbus.dll", EntryPoint = "modbus_free",
    CharSet = CharSet.Ansi)]
    public static extern void modbus_free(IntPtr ctx);
    //测试
    [DllImport("modbus.dll", EntryPoint = "modbus_new_rtu",
    CharSet = CharSet.Ansi)]
    public static extern void modbus_new_rtu(IntPtr ctx);

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