MODBUS RTU协议的仪表通信时需要进行CRC校验，单片机可以用此程序生成CRC校验码，多项式是0xA001
所用单片机为STC15系列单片机，不过CRC生成过程很简单，通用的51单片机都可以生成(MODBUS RTU protocol instrument communication needs CRC verification, SCM can use this procedure to generate CRC checksum, the polynomial is 0xA001
The microcontroller used for the STC15 series microcontroller, but the CRC generation process is very simple, general 51 microcontroller can be generated)