Change log:
- Default mode is changed from legacy to fast because legacy mode suffer issues caused by O.S delays
- Add support for Modbus function 11 : Get Comm Event Counter
- Add support for Modbus function 12 : Get Comm Event Log
- Add support for Modbus function 17 : Report server ID
- Add support for Modbus function 43 / MEI 14 : Read device id
- Improve serial communication robustness