The function write-serial-port-char writes the character char to the serial port associated with serial-port , and returns char .
A timeout will occur if the character cannot be written before the write timeout (as specified by values given when the serial port was opened by open-serial-port).
When a timeout occurs, if
timeout-error-p
is non-nil, then an error of type
serial-port-timeout
is signalled, otherwise
nil
is returned. The default value of
timeout-error-p
is
t
.