说明：  基于MSP430FE427单片机的RS485源码，485没有使能端，利用串口助手2.1，发一组数据被单片机接受后返回。完全符合645协议，其中数据域接受时减0x33，发送时加0x33。所以收到的数据效验码与发送的会不同。
(RS485-based SCM MSP430FE427 source, 485 is not enabled client, using assistant serial 2.1, the one set of data has been accepted to return to single-chip microcomputer. In full compliance with the 645 agreement, which the data field accepted by 0x33, sent plus 0x33. Therefore, the data received and sent well-tested code will be different.)