基于Netty框架开发的Modbus源代码。支持*READCOILS|0x01*READDISCRETEINPUTS|0x02*READHOLDINGREGISTERS|0x03*READINPUTREGISTERS|0x04*WRITESINGLECOIL|0x05*WRITESINGLEREGISTER|0x06*WRITEMULTIPLECOILS|0x0F*WRITEMULTIPLEREGISTERS|0x10