FreeModbus Slave RTU 精简版源代码【worldsing 笔记】

RTU精简版本

测试环境：IAR for avr 5.40 + M128
目前只优化了ModBusPort.c和ModBusRTU.c
ModBusPort.c  
  566 bytes of CODE memory (+ 19 bytes shared)
  4 bytes of DATA memory (+ 13 bytes shared)
ModBusRTU.c  
   1 677 bytes of CODE memory (+ 14 bytes shared)
   821 bytes of DATA memory (+  1 byte  shared)
ModbusFun.c  
   1 582 bytes of CODE memory
ModbusUser.c  
   548 bytes of CODE memory (+ 14 bytes shared)
  30 bytes of DATA memory