0: 8,N,2 for RTU (MODBUS)
1: 8,E,1 for RTU (MODBUS)
2: 8,O,1 for RTU (MODBUS)
3: 7,N,2 for ASCII (MODBUS)
4: 7,E,1 for ASCII(MODBUS)
5: 7,O,1 for ASCII(MODBUS)
6: 8,N,1 free communication format
7:8,E,1 free communication format
8: 8,O,1 free communication format
9:Host mode, send current running frequency