利用netty實現Modbus TCP client/server READ COILS | 0x01 READ DISCRETE INPUTS | 0x02 READ HOLDING REGISTERS | 0x03 READ INPUT REGISTERS | 0x04 WRITE SINGLE COIL | 0x05 WRITE SINGLE REGISTER | 0x06 WRITE MULTIPLE COILS | 0x0F WRITE MULTIPLE REGISTERS | 0x10