0: there is no error
1: invalid serial port
2: invalid serial port mode
3: invalid baud rate
4: invalid data bits
5: invalid parity
6: invalid stop bits
7: invalid modem signal parameter
8: invalid UART RX Threshold
parameter
9: invalid time-out parameter
10: serial port busy
11: UART hardware error
12: remote hardware error
20: invalid transmission buffer size
21: invalid modem signal method
22: time-out of CTS = true
23: time-out of CTS = false
24: transmission time-out error
30: invalid reception buffer size
31: reception time-out error
32: flow control configured differently
from the manual
33: invalid flow control for the
configured serial port
34: data reception not allowed in the
normal mode
35: data reception not allowed in the
extended mode
36: DCD interruption not allowed
37: CTS interruption not allowed
38: DSR interruption not allowed
39: serial port not configured
50: internal error in the serial port